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{{Short description|Interplay between observation, experiment, and theory in science}}
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{{hatnote|For notable practitioners in previous centuries, see [[History of scientific method]].}}
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{{Use dmy dates|cs1-dates=ly|date=August 2021}}
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{{Science|expanded=Overview}}
The '''scientific method''' is an [[Empirical evidence|empirical]] method for acquiring [[knowledge]] that has characterized the development of [[science]] since at least the 17th century. The scientific method involves careful [[observation]] coupled with rigorous [[skepticism|scepticism]], because [[Philosophy of science#Observation inseparable from theory|cognitive assumptions]] can distort the interpretation of the [[Perception#Process and terminology|observation]]. Scientific inquiry includes creating a [[hypothesis]] through [[inductive reasoning]], testing it through experiments and statistical analysis, and adjusting or discarding the hypothesis based on the results.<ref name="principia">{{Cite book|title=Philosophiæ Naturalis Principia Mathematica|last=Newton|first=Isaac|series=The Principia: Mathematical Principles of Natural Philosophy |publisher=University of California Press|others=Includes "A Guide to Newton's Principia" by I. Bernard Cohen, pp. 1–370. (The ''Principia'' itself is on pp. 371–946)|isbn=978-0-520-08817-7|location=Berkeley, CA|date=1999|at=791–796 ("Rules of Reasoning in Philosophy"); ''see also'' [[Philosophiæ Naturalis Principia Mathematica#Rules of Reason]]|translator-last=Cohen|translator-first=I. Bernard|trans-title=Mathematical Principles of Natural Philosophy|orig-year=1726 (3rd ed.)|translator-last2=Whitman|translator-first2=Anne|translator-last3=Budenz|translator-first3=Julia|title-link=Philosophiæ Naturalis Principia Mathematica}}</ref><ref>{{Citation|title=Oxford Dictionaries: British and World English|date=2016|chapter-url=http://www.oxforddictionaries.com/definition/english/scientific-method|chapter=scientific method|access-date=28 May 2016|archive-date=2016-06-20 |archive-url=https://web.archive.org/web/20160620062539/http://www.oxforddictionaries.com/definition/english/scientific-method|url-status=dead}}</ref><ref>{{Cite book|url=http://www.oed.com/view/Entry/383323|title=Oxford English Dictionary|via=OED Online|publisher=Oxford University Press|year=2014|edition=3rd|location=Oxford|url-access=subscription|access-date=2018-05-31 |archive-date=2023-11-29 |archive-url=https://web.archive.org/web/20231129112639/https://www.oed.com/dictionary/scientific-method_n|url-status=live}}</ref>

Although procedures vary between [[Branches of science|fields]], the underlying [[#Process|process]] is often similar. The  scientific method involves making [[conjecture]]s (hypothetical explanations), predicting the logical consequences of hypothesis, then carrying out experiments or empirical observations based on those predictions.<ref name="NA">{{cite wikisource|title=A Neglected Argument for the Reality of God|date=1908|first=Charles Sanders|last=Peirce|wslink=A Neglected Argument for the Reality of God|volume=7|pages=90–112|journal=Hibbert Journal}} with added notes. Reprinted with previously unpublished part, ''Collected Papers'' v. 6, paragraphs 452–85, ''The Essential Peirce'' v. 2, pp. 434–450, and elsewhere. N.B. 435.30 'living institution': Hibbert J. mis-transcribed 'living institution': ("constitution" for "institution")</ref> A hypothesis is a conjecture based on knowledge obtained while seeking answers to the question. Hypotheses can be very specific or broad but must be [[falsifiable]], implying that it is possible to identify a possible outcome of an experiment or observation that conflicts with predictions deduced from the hypothesis; otherwise, the hypothesis cannot be meaningfully tested.{{sfnp|Popper|1959|p=273}}

While the scientific method is often presented as a fixed sequence of steps, it actually represents a set of general principles. Not all steps take place in every [[#Scientific inquiry|scientific inquiry]] (nor to the same degree), and they are not always in the same order.<ref name="allScience">{{harvp|Gauch|2003|p=3}}: "The scientific method 'is often misrepresented as a fixed sequence of steps,' rather than being seen for what it truly is, 'a highly variable and creative process' (AAAS 2000:18). The claim here is that science has general principles that must be mastered to increase productivity and enhance perspective, not that these principles provide a simple and automated sequence of steps to follow."</ref><ref name="Inductive Science 1837">[[William Whewell]], ''History of Inductive Science'' (1837), and in ''Philosophy of Inductive Science'' (1840)</ref>

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== History ==
{{Main|History of scientific method}}
{{For timeline|Timeline of the history of the scientific method}}

The history of scientific method considers changes in the methodology of scientific inquiry, not the [[history of science]] itself. The development of rules for [[scientific reasoning]] has not been straightforward; scientific method has been the subject of intense and recurring debate throughout the history of science, and eminent natural philosophers and scientists have argued for the primacy of various approaches to establishing scientific knowledge.

Different early expressions of [[empiricism]] and the scientific method can be found throughout history, for instance with the ancient [[Stoics]], [[Epicurus]],<ref name=Asmis>Elizabeth Asmis (1985) ''Epicurus' Scientific Method''. Cornell University Press</ref> [[Alhazen]],{{efn-ua|name= vacuum| Twenty-three hundred years ago, Aristotle proposed that a [[vacuum]] did not exist in nature; thirteen hundred years later, [[#alhazen|Alhazen disproved Aristotle's hypothesis]], using experiments on [[refraction]],<ref name=treatiseOnLight2>Alhacen (c.1035) ''Treatise on Light'' (رسالة في الضوء) as cited in [[Shmuel Sambursky]], ed. (1975) [https://archive.org/details/physicalthoughtf0000unse/page/136/mode/2up Physical thought from the Presocratics to the quantum physicists : an anthology], p.137</ref> thus deducing the existence of [[outer space]].<ref name= alhacenOnRefraction4.28 />}}{{efn|name= alhacenCharacterizes| ''[[Book of Optics]]'' (''circa'' 1027) After anatomical investigation of the human eye, and an exhaustive study of human visual perception, Alhacen characterizes the first postulate of [[Euclid's Optics]] as 'superfluous and useless' 
(Book I, [6.54] —thereby overturning Euclid's, Ptolemy's, and Galen's [[Emission theory (vision)|emission theory of vision, using logic and deduction from experiment. He showed Euclid's first postulate of Optics to be hypothetical only, and fails to account for his experiments.]]), and deduces that light must enter the eye, in order for us to see. He describes the [[camera obscura]] as part of this investigation.}}{{efn-ua|1=[[Alhazen]] argued the importance of forming questions and subsequently testing them: "How does light travel through transparent bodies? Light travels through transparent bodies in straight lines only... We have explained this exhaustively in our ''[[Book of Optics]]''.{{efn|name= straightLinesOnly }} But let us now mention something to prove this convincingly: the fact that light travels in straight lines is clearly observed in the lights which enter into dark rooms through holes.... [T]he entering light will be clearly observable in the dust which fills the air.<ref name=treatiseOnLight>Alhazen, ''Treatise on Light'' ({{lang|ar|رسالة في الضوء}}), translated into English from German by M. Schwarz, from [http://menadoc.bibliothek.uni-halle.de/dmg/periodical/pageview/30949 "Abhandlung über das Licht"] {{Webarchive|url=https://web.archive.org/web/20191230190424/http://menadoc.bibliothek.uni-halle.de/dmg/periodical/pageview/30949 |date=2019-12-30  }}, J. Baarmann (editor and translator from Arabic to German, 1882) ''[[Zeitschrift der Deutschen Morgenländischen Gesellschaft]]'' Vol '''36''' as quoted in {{harvp|Sambursky|1975|p=136}}.</ref>
* He demonstrated his conjecture that "light travels through transparent bodies in straight lines only" by placing a straight stick or a taut thread next to the light beam, as quoted in {{harvp|Sambursky|1975|p=136}} to prove that light travels in a straight line.
* [[David Hockney]] cites Alhazen several times as the likely source for the portraiture technique using the [[camera obscura]], which Hockney rediscovered with the aid of an optical suggestion from [[Charles M. Falco]]. ''Kitab al-Manazir'', which is Alhazen's ''[[Book of Optics]]'', at that time denoted ''Opticae Thesaurus, Alhazen Arabis'', was translated from Arabic into Latin for European use as early as 1270. Hockney cites Friedrich Risner's 1572 Basle edition of ''Opticae Thesaurus''. Hockney quotes Alhazen as the first clear description of the camera obscura.<ref name= truthSought4sake >{{harvp|Hockney|2006|p=240}}:
"Truth is sought for its own sake. And those who are engaged upon the quest for anything for its own sake are not interested in other things. Finding the truth is difficult, and the road to it is rough." – [[Alhazen]] ([[Ibn Al-Haytham]] 965 – c. 1040) ''[[Critique of Ptolemy]]'', translated by S. Pines, ''Actes X Congrès internationale d'histoire des sciences'', Vol '''I''' Ithaca 1962, as quoted in {{harvp|Sambursky|1975|p=139}}. (This quotation is from Alhazen's critique of Ptolemy's books ''[[Almagest]]'', ''Planetary Hypotheses'', and {{cite book |title=Ptolemy's Theory of Visual Perception: An English Translation of the Optics |publisher=American Philosophical Society |isbn=9780871698629 |year=1996 |url=https://books.google.com/books?id=mhLVHR5QAQkC&dq=Opticae+thesaurus+alhazen&pg=PA59 |translator=A. Mark Smith |access-date=2021-11-27  |archive-date=2023-11-29  |archive-url=https://web.archive.org/web/20231129112635/https://books.google.com/books?id=mhLVHR5QAQkC&dq=Opticae+thesaurus+alhazen&pg=PA59#v=onepage&q=Opticae%20thesaurus%20alhazen&f=false |url-status=live }})</ref>}}{{efn-lr|name=Tanqih }} [[Ibn Sina|Avicenna]], [[Al-Biruni]],{{sfnp|Alikuzai|2013|p=154}}{{sfnp|Rozhanskaya|Levinova|1996}} [[Roger Bacon]]{{efn-lg|His assertions in the ''{{lang|la|Opus Majus}}'' that "theories supplied by reason should be verified by sensory data, aided by instruments, and corroborated by trustworthy witnesses"<ref>Bacon, ''Opus Majus'', Bk.&VI.</ref> were (and still are) considered "one of the first important formulations of the scientific method on record".{{sfnp|Borlik|2011|p=[https://books.google.com/books?id=c_ShAgAAQBAJ&pg=PA132 132]}}}}, and [[William of Ockham]]. 

In the [[scientific revolution]] of the 16th and 17th centuries some of the most important developments were the furthering of [[empiricism]] by [[Francis Bacon]] and [[Robert Hooke]],<ref>{{Cite book| last = Inwood | first = Stephen | title = The Forgotten Genius : The biography of Robert Hooke (1635–1703) | publisher = MacAdam/Cage Pub. |location=San Francisco | year = 2003 | isbn = 978-1-931561-56-3 |oclc=53006741 |pages=112–116}}</ref><ref>{{cite book |title=The posthumous works of Robert Hooke, M.D. S.R.S. Geom. Prof. Gresh. etc. |year=1705 |first=Robert |last=Hooke |editor-first=Richard |editor-last=Waller  |chapter-url=https://archive.org/details/b30454621_0001/page/3/mode/1up  |chapter=First general: The present state of natural philosophy and wherein it is deficient}}</ref> the [[rationalist]] approach described by [[René Descartes]] and [[inductivism]], brought to particular prominence by [[Isaac Newton]] and those who followed him. Experiments were advocated by [[Francis Bacon]], and performed by [[Giambattista della Porta]],<ref>{{cite conference |conference=The optics of Giovan Battista della Porta (1535–1615): A Reassessment Workshop at Technische Universität Berlin, 24–25 October 2014 |url=http://www.wissensgeschichte-berlin.de/sites/default/files/2014_10_24_DellaPortaWS_Program_Abstracts.pdf |title=various papers |url-status=dead |archive-url=https://web.archive.org/web/20180527202632/http://www.wissensgeschichte-berlin.de/sites/default/files/2014_10_24_DellaPortaWS_Program_Abstracts.pdf |archive-date=2018-05-27}}</ref> [[Johannes Kepler]],{{refn|1=Kepler, Johannes (1604) ''Ad Vitellionem paralipomena, quibus astronomiae pars opticae traditur'' (Supplements to Witelo, in which the optical part of astronomy is treated){{efn|The full title translation is from {{harvp|Voelkel|2001|p=60}}.}} as cited in {{cite journal |last1=Smith |first1=A. Mark|title=What Is the History of Medieval Optics Really about?|journal=Proceedings of the American Philosophical Society|date=June 2004 |volume=148 |issue=2|pages=180–194|jstor=1558283 |pmid=15338543}}
}}{{efn|name= Kepler1604| Kepler was driven to this experiment after observing the partial solar eclipse at Graz, July 10, 1600. He used Tycho Brahe's method of observation, which was to project the image of the Sun on a piece of paper through a pinhole aperture, instead of looking directly at the Sun. He disagreed with Brahe's conclusion that total eclipses of the Sun were impossible because there were historical accounts of total eclipses. Instead, he deduced that the size of the aperture controls the sharpness of the projected image (the larger the aperture, the more accurate the image&nbsp;– this fact is now fundamental for optical system design). {{harvp|Voelkel|2001|p=61}}, notes that Kepler's 1604 experiments produced the first correct account of vision and the eye, because he realized he could not accurately write about astronomical observation by ignoring the eye. {{harvp|Smith|2004|p=192}} recounts how Kepler used Giambattista della Porta's water-filled glass spheres to model the eye, and using an aperture to represent the entrance pupil of the eye, showed that the entire scene at the entrance pupil-focused on a single point of the rear of the glass sphere (representing the retina of the eye). This completed Kepler's investigation of the optical train, as it satisfied his application to astronomy.}} and [[Galileo Galilei]].{{efn-lg|name= empirical|...an experimental approach was advocated by Galileo in 1638 with the publication of ''[[Two New Sciences]]''.{{sfnp|Galileo Galilei|1638}}}} There was particular development aided by theoretical works by a skeptic [[Francisco Sanches]],{{sfnp|Sanches|1988}}  by idealists as well as empiricists [[John Locke]], [[George Berkeley]], and [[David Hume]].{{efn|name= particDev |1= Sanches and Locke were both physicians. By his training in Rome and France, Sanches sought a method of science beyond that of the Scholastic Aristotelian school. Botanical gardens were added to the universities in Sanches' time to aid medical training before the 1600s. ''See Locke [https://en.wikiquote.org/wiki/John_Locke#An_Essay_Concerning_Human_Understanding_(1689) (1689) An Essay Concerning Human Understanding]'' Berkeley served as foil to the materialist System of the World of Newton; Berkeley emphasizes that scientist should seek 'reduction to regularity'.<ref name= idealism >Lisa Downing, ''Stanford Encyclopedia of Philosophy'' [https://plato.stanford.edu/entries/berkeley/#3.2.3 (Fall 2021) George Berkeley, 3.2.3 Scientific explanation]</ref> Atherton (ed.) 1999 selects Locke, Berkeley, and Hume as part of the empiricist school.<ref>Margaret Atherton (ed.) 1999 [https://books.google.com/books?id=iifXAAAAMAAJ The Empiricists]</ref> }} [[C. S. Peirce]] formulated the [[hypothetico-deductive model]] in the 20th century, and the model has undergone significant revision since.{{sfnp|Godfrey-Smith|2003|p=236}}

The term "scientific method" emerged in the 19th century, as a result of significant institutional development of science, and terminologies establishing clear [[Demarcation problem|boundaries]] between science and non-science, such as "scientist" and "pseudoscience", appearing.{{sfnp|Thurs|2011}} Throughout the 1830s and 1850s, when Baconianism was popular, naturalists like William Whewell, John Herschel and John Stuart Mill engaged in debates over "induction" and "facts" and were focused on how to generate knowledge.{{sfnp|Thurs|2011}} In the late 19th and early 20th centuries, a debate over [[Philosophical realism|realism]] vs. [[antirealism]] was conducted as powerful scientific theories extended beyond the realm of the observable.<ref name="auto">{{cite book |last=Achinstein |first= Peter |chapter=General Introduction |pages=1–5 |title=Science Rules: A Historical Introduction to Scientific Methods |publisher=Johns Hopkins University Press |date=2004 |isbn=978-0-8018-7943-2}}</ref>

=== Modern use and critical thought ===
{{anchor|theTermSci}}The term "scientific method" came into popular use in the twentieth century; [[#CITEREFDewey1910|Dewey's 1910 book]], ''[[How We Think]]'', inspired [[#aGuideline|popular guideline]]s,<ref name= cowles>{{harvp|Cowles|2020|p=264}}</ref> appearing in dictionaries and science textbooks, although there was little consensus over its meaning.{{sfnp|Thurs|2011}} Although there was growth through the middle of the twentieth century,{{efn|name= deweySchool|1= On Dewey's Laboratory school in 1902: Cowles 2020 notes that Dewey regarded the Lab school as a collaboration between teachers and students. The five-step exposition was taken as mandatory, rather than descriptive. Dismayed by the Procrustean interpretation, Dewey attempted to tone down his five-step scheme by re-naming the steps to phases. The edit was ignored.}} by the 1960s and 1970s numerous influential philosophers of science such as [[Thomas Kuhn]] and [[Paul Feyerabend]] had questioned the universality of the "scientific method" and in doing so largely replaced the notion of science as a homogeneous and universal method with that of it being a heterogeneous and local practice.{{sfnp|Thurs|2011}} In particular, {{anchor|critiquesOfFeyerabend}}Paul Feyerabend, in the 1975 first edition of his book ''[[Against Method]]'', argued against there being any universal rules of [[science]];<ref name="auto"/> [[Karl Popper]],{{efn-lg|Popper, in his 1963 publication of ''Conjectures and Refutations'' argued that merely [[Trial and error|Trial and Error]] can stand to be called a 'universal method'.<ref name= trialAndErr>{{ citation | mode=cs1 | url= http://www.paul-rosenfels.org/Popper.pdf | last= Popper | author-link= Karl Popper | date= 1963 | title= Conjectures and Refutations | pages=312–365 |archive-url=https://web.archive.org/web/20171013124349/http://www.paul-rosenfels.org/Popper.pdf |archive-date =2017-10-13 |ref=none | quote=If we have made this our task, then there is no more rational procedure than the method of trial and error--of conjecture and refutation}}</ref>}} and Gauch 2003,<ref name= allScience /> disagree with Feyerabend's claim.

Later stances include physicist [[Lee Smolin]]'s 2013 essay "There Is No Scientific Method",<ref name="Smolin 2013">{{cite web |url=http://bigthink.com/in-their-own-words/there-is-no-scientific-method |title=There is No Scientific Method |last1=Smolin |first1=Lee |access-date=2016-06-07 |date=May 2013 |archive-date=2016-08-07  |archive-url=https://web.archive.org/web/20160807052038/http://bigthink.com/in-their-own-words/there-is-no-scientific-method |url-status=live }}</ref> in which he espouses two [[#ethicalPosition|ethical principle]]s,{{efn-lg|name= ethicalPosition|Lee Smolin, in his 2013 essay "There Is No Scientific Method",<ref name="Smolin 2013" /> espouses two [[#ethicalPosition|ethical principle]]s. Firstly: "we agree to tell the truth and we agree to be governed by rational argument from public evidence". And secondly, that ..."when the evidence is not sufficient to decide from rational argument, whether one point of view is right or another point of view is right, we agree to encourage competition and diversification". Thus echoing {{harvp|Popper|1963|p=viii}}}} and [[History of science|historian of science]] Daniel Thurs' chapter in the 2015 book ''Newton's Apple and Other Myths about Science'', which concluded that the scientific method is a myth or, at best, an idealization.<ref name="Thurs2015">{{Citation | last = Thurs | first = Daniel P. | chapter = That the scientific method accurately reflects what scientists actually do | editor-last1 = Numbers | editor-first1 = Ronald L. | editor-link = Ronald L. Numbers | editor-last2 = Kampourakis | editor-first2 = Kostas | title = Newton's Apple and Other Myths about Science | pages = 210–218 | publisher = Harvard University Press | year = 2015 | chapter-url = https://books.google.com/books?id=pWouCwAAQBAJ&q=newton%27s+apple+and+other+myths+about+science | isbn = 978-0-674-91547-3 | quote = It's probably best to get the bad news out of the way first, the so-called scientific method is a myth.&nbsp;... If typical formulations were accurate, the only location true science would be taking place in would be grade-school classrooms. | access-date = 2020-10-20  | archive-date = 2023-11-29  | archive-url = https://web.archive.org/web/20231129112729/https://books.google.com/books?id=pWouCwAAQBAJ&q=newton%27s+apple+and+other+myths+about+science#v=snippet&q=newton's%20apple%20and%20other%20myths%20about%20science&f=false | url-status = live }}</ref> As [[#Beliefs and biases|myth]]s are beliefs,<ref name= beliefCreatesReality /> they are subject to the [[narrative fallacy]] as Taleb points out.<ref name= narrativeFallacy /> Philosophers [[Robert Nola]] and Howard Sankey, in their 2007 book ''Theories of Scientific Method'', said that debates over the scientific method continue, and argued that Feyerabend, despite the title of ''Against Method'', accepted certain rules of method and attempted to justify those rules with a meta methodology.<ref>{{cite book |last1=Nola |first1=Robert |author1-link= Robert Nola |last2=Sankey |first2=Howard |date=2007 |title=Theories of Scientific Method: An Introduction |series=Philosophy and science |volume=2 |location=Montréal |publisher=[[McGill–Queen's University Press]] |pages=[https://books.google.com/books?id=aKjgBQAAQBAJ&pg=PA1 1], [https://books.google.com/books?id=aKjgBQAAQBAJ&pg=PA300 300] |isbn=9780773533448 |oclc=144602109 |doi=10.4324/9781315711959 |quote=There is a large core of people who think there is such a thing as a scientific method that can be justified, although not all agree as to what this might be. But there are also a growing number of people who think that there is no method to be justified. For some, the whole idea is yesteryear's debate, the continuation of which can be summed up as yet more of the proverbial 'flogging a dead horse'. We beg to differ.&nbsp;... We shall claim that Feyerabend did endorse various scientific values, did accept rules of method (on a certain understanding of what these are), and did attempt to justify them using a meta methodology somewhat akin to the principle of [[reflective equilibrium]].}}</ref> 
Staddon (2017) argues it is a mistake to try following rules in the absence of an algorithmic scientific method; in that case, "science is best understood through examples".<ref name="Staddon 2017 p.">{{cite book |last=Staddon |first=John | title=Scientific Method: How Science Works, Fails to Work, and Pretends to Work | publisher=Routledge | publication-place=New York | date=2017-12-01 | isbn=978-1-315-10070-8 | doi=10.4324/9781315100708 | page=}}</ref><ref>{{cite web| url = https://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/21425/StaddonHistoryofScienceSept2020.pdf?sequence=2&isAllowed=y| title = Whatever Happened to History of Science?| date = 16 September 2020| access-date = 2021-08-27 | archive-date = 2021-08-27 | archive-url = https://web.archive.org/web/20210827092318/https://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/21425/StaddonHistoryofScienceSept2020.pdf?sequence=2&isAllowed=y| url-status = live| last1 = Staddon| first1 = John|quote="science is best understood through examples"}}</ref> But algorithmic methods, such as ''disproof of existing theory by experiment'' have been used since [[Alhacen]] (1027) and his ''[[Book of Optics]]'',{{efn|name= alhacenCharacterizes}} and Galileo (1638) and his ''Two New Sciences'',{{sfnp|Galileo Galilei|1638}} and ''The Assayer'',<ref name= ilSaggiatore /> which still stand as scientific method.

==Elements of inquiry<span class="anchor" id="Elements of the scientific method"></span>==
{{anchor|Context}}The basic elements of the scientific method are illustrated by the following example (which occurred from 1944 to 1953) from the discovery of the structure of DNA (marked with [[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] and indented).

=== Overview ===

[[File:The Scientific Method.svg|thumb|upright=1|The scientific method is often represented as an [[#Elements of the scientific method|ongoing process]]. This diagram represents one variant, and [[commons:Category:Scientific method|there are many others]].]]

The scientific method is the process by which [[science]] is carried out.<ref name="allTheSciences">{{harvp|Gauch|2003|p=xv}}: "The thesis of this book, as outlined in Chapter One, is that there are general principles applicable to all the sciences."</ref> As in other areas of inquiry, science (through the scientific method) can build on previous knowledge, and unify understanding of its studied topics over time.{{efn|name=unification|1= The topics of study, as expressed in the vocabulary of its scientists, are approached by a "single unified method".<ref name= cowles />{{rp|pp.8,13,33–35,60}} The topics are [[Unification (computer science)|unified]] by its predicates, in a system of expressions. The unification process was formalized by [[Jacques Herbrand]] in 1930.<ref name= herbrand >Maribel Fernández [https://nms.kcl.ac.uk/maribel.fernandez/papers/slides-TCS-SOUP.pdf (Dec 2007) Unification Algorithms]</ref>}} This model can be seen to underlie the [[scientific revolution]].<ref name="lindberg2007">{{harvp|Lindberg|2007|pp=2–3}}: "There is a danger that must be avoided. ... If we wish to do justice to the historical enterprise, we must take the past for what it was. And that means we must resist the temptation to scour the past for examples or precursors of modern science. ...My concern will be with the beginnings of scientific ''theories'', the methods by which they were formulated, and the uses to which they were put; ... "</ref>

The overall process involves making [[conjecture]]s ([[Hypothesis|hypotheses]]), predicting their logical consequences, then carrying out experiments based on those predictions to determine whether the original conjecture was correct.<ref name="NA" /> However, there are difficulties in a formulaic statement of method. Though the scientific method is often presented as a fixed sequence of steps, these actions are more accurately general principles.{{sfnp|Gauch|2003|p=3}} Not all steps take place in every scientific inquiry (nor to the same degree), and they are not always done in the same order. 

==== Factors of scientific inquiry ====
There are different ways of outlining the basic method used for scientific inquiry. The [[scientific community]] and [[philosophers of science]] generally agree on the following classification of method components. These methodological elements and organization of procedures tend to be more characteristic of [[experimental science]]s than [[social science]]s. Nonetheless, the cycle of formulating hypotheses, testing and analyzing the results, and formulating new hypotheses, will resemble the cycle described below.{{anchor|epistemicCycle|Process}}The scientific method is an iterative, cyclical process through which information is continually revised.<ref>{{cite book |last1=Godfrey-Smith |first1=Peter |url=https://books.google.com/books?id=k23egtSWrb8C |title=Theory and Reality: An Introduction to the Philosophy of Science |date=2009 |publisher=University of Chicago Press |isbn=978-0-226-30062-7 |location=Chicago |author-link=Peter Godfrey-Smith |access-date=2020-05-09 |archive-url=https://web.archive.org/web/20231129112726/https://books.google.com/books?id=k23egtSWrb8C |archive-date=2023-11-29 |url-status=live}}</ref><ref name="Brody-1993">{{harvp|Brody|1993|p=10}} calls this an ''[[#epistemicCycle|epistemic cycle]]''; these cycles can occur at high levels of abstraction.</ref> It is generally recognized to develop advances in knowledge through the following elements, in varying combinations or contributions:<ref name="Fixation">{{cite wikisource|title=The Fixation of Belief|first=Charles Sanders|last=Peirce|year=1877|wslink=The Fixation of Belief|volume=12|pages=1–15|journal=Popular Science Monthly}}.</ref><ref name="Vital">Peirce, Charles S., ''Collected Papers'' v. 5, in paragraph 582, from 1898: "...&nbsp;[rational] inquiry of every type, fully carried out, has the vital power of self-correction and of growth. This is a property so deeply saturating its inmost nature that it may truly be said that there is but one thing needful for learning the truth, and that is a hearty and active desire to learn what is true."</ref><!--ref>{{cite book|last1=Kuhn |first1=Thomas S.|title=The Structure of Scientific Revolutions 50th Anniversary Edition|date=2012 |publisher=University of Chicago Press|location=Chicago|isbn=978-0-226-45811-3 |url=https://books.google.com/books?id=3eP5Y_OOuzwC|access-date=29 January 2018}}{{pn|date=August 2021}}</ref><ref>{{cite book|last1=Galison |first1=Peter|title=How Experiments End|date=1987|publisher=University of Chicago Press|location=Chicago|isbn=978-0-226-27915-2|url=https://books.google.com/books?id=DN-9m2jSo8YC |access-date=29 January 2018}}</ref-->
* Characterizations (observations, definitions, and measurements of the subject of inquiry)
* Hypotheses (theoretical, hypothetical explanations of observations and measurements of the subject)
* Predictions (inductive and deductive reasoning from the hypothesis or theory)
* Experiments (tests of all of the above)
Each element of the scientific method is subject to [[peer review]] for possible mistakes. These activities do not describe all that scientists do but [[#Beliefs and biases|apply mostly to experimental sciences]] (e.g., physics, chemistry, biology, and psychology). The elements above are often taught in [[education|the educational system]] as "the scientific method".{{efn-ua|name= aQuestion| In the [[Inquiry-based learning|inquiry-based education]] paradigm, the stage of "characterization, observation, definition, ..." is more briefly summed up under the rubric of a Question. The question at some stage might be as basic as the [[5Ws]], or ''is this answer true?'', or ''who else might know this?'', or ''can I ask them?'', and so forth. The questions of the inquirer spiral until the goal is reached.}}

The scientific method is not a single recipe: it requires intelligence, imagination, and creativity.<ref>{{harvp|Einstein|Infeld|1938|p=92}}: "To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science."</ref> In this sense, it is not a mindless set of standards and procedures to follow but is rather an [[#Evaluation and improvement|ongoing cycle]], constantly developing more useful, accurate, and comprehensive models and methods. For example, when Einstein developed the Special and General Theories of Relativity, he did not in any way refute or discount Newton's ''Principia''. On the contrary, if the astronomically massive, the feather-light, and the extremely fast are removed from Einstein's theories – all phenomena Newton could not have observed – Newton's equations are what remain. Einstein's theories are expansions and refinements of Newton's theories and, thus, increase confidence in Newton's work.

{{anchor|aGuideline}}An iterative,<ref name="Brody-1993" /> pragmatic<ref name="truthSought4sake" /> scheme of the four points above is sometimes offered as a guideline for proceeding:<ref>{{cite journal |vauthors=Crawford S, Stucki L |year=1990 |title=Peer review and the changing research record |journal=Journal of the American Society for Information Science |volume=41 |issue=3 |pages=223–228 |doi=10.1002/(SICI)1097-4571(199004)41:3<223::AID-ASI14>3.0.CO;2-3}}</ref>

# Define a question
# Gather information and resources (observe)
# Form an explanatory hypothesis
# Test the hypothesis by performing an experiment and collecting data in a [[Reproducibility|reproducible]] manner
# Analyze the data
# Interpret the data and draw conclusions that serve as a starting point for a new hypothesis
# Publish results
# Retest (frequently done by other scientists)

The iterative cycle inherent in this step-by-step method goes from point 3 to 6 and back to 3 again.

While this schema outlines a typical hypothesis/testing method,{{sfnp|Gauch|2003|loc=esp. chapters 5–8}} many philosophers, historians, and sociologists of science, including [[Paul Feyerabend]],{{efn|name= descartes| "no opinion, however absurd and incredible, can be imagined, which has not been maintained by some of the philosophers". —Descartes<ref name= discourseOnMethod >[[René Descartes]] (1637) [https://en.wikisource.org/wiki/Discourse_on_the_Method/Part_2 Discourse on the Method/Part 2] {{Webarchive|url=https://web.archive.org/web/20210901150801/https://en.wikisource.org/wiki/Discourse_on_the_Method/Part_2 |date=2021-09-01  }} Part II</ref> }} claim that such descriptions of scientific method have little relation to the ways that science is actually practiced.

=== <span class="anchor" id="DNA-characterizations"></span> Characterizations===
<blockquote>[[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] In 1950, it was known that [[genetic inheritance]] had a mathematical description, starting with the studies of [[Gregor Mendel]], and that DNA contained genetic information (Oswald Avery's ''transforming principle'').{{sfnp|McCarty|1985|page=252}} But the mechanism of storing genetic information (i.e., genes) in DNA was unclear. Researchers in [[William Lawrence Bragg|Bragg's]] laboratory at [[University of Cambridge|Cambridge University]] made [[X-ray]] [[diffraction]] pictures of various [[molecule]]s, starting with [[crystal]]s of [[salt]], and proceeding to more complicated substances. Using clues painstakingly assembled over decades, beginning with its chemical composition, it was determined that it should be possible to characterize the physical structure of DNA, and the X-ray images would be the vehicle.{{sfnp|McElheny|2004|p=34}}</blockquote>

The scientific method depends upon increasingly sophisticated characterizations of the subjects of investigation. (The ''subjects'' can also be called [[:Category:Lists of unsolved problems|''unsolved problems'']] or the ''unknowns''.){{efn-ua|name= aQuestion}} For example, [[Benjamin Franklin]] conjectured, correctly, that [[St. Elmo's fire]] was [[electrical]] in [[nature]], but it has taken a long series of experiments and theoretical changes to establish this. While seeking the pertinent properties of the subjects, careful thought may also [[logical consequence|entail]] some definitions and [[observations]]; these observations often demand careful [[measurements]] and/or counting can take the form of expansive [[empirical research]]. 

A [[Research question|scientific question]] can refer to the explanation of a specific [[observation]],{{efn-ua|name= aQuestion}} as in "Why is the sky blue?" but can also be open-ended, as in "How can I [[Drug design|design a drug]] to cure this particular disease?" This stage frequently involves finding and evaluating evidence from previous experiments, personal scientific observations or assertions, as well as the work of other scientists. If the answer is already known, a different question that builds on the evidence can be posed. When applying the scientific method to research, determining a good question can be very difficult and it will affect the outcome of the investigation.<ref>{{cite book |url=https://books.google.com/books?id=C7pZftbI0ZMC |title=Translational and Experimental Clinical Research |publisher=Lippincott Williams & Wilkins |year=2005 |isbn=9780781755658 |editor-last1=Schuster |editor-first1=Daniel P. |chapter=Ch. 1 |access-date=2021-11-27 |editor-last2=Powers |editor-first2=William J. |archive-url=https://web.archive.org/web/20231129112636/https://books.google.com/books?id=C7pZftbI0ZMC |archive-date=2023-11-29 |url-status=live}} This chapter also discusses the different types of research questions and how they are produced.</ref>

The systematic, careful collection of measurements or counts of relevant quantities is often the critical difference between [[Pseudoscience|pseudo-sciences]], such as alchemy, and science, such as chemistry or biology. Scientific measurements are usually tabulated, graphed, or mapped, and statistical manipulations, such as [[correlation]] and [[regression analysis|regression]], performed on them. The measurements might be made in a controlled setting, such as a laboratory, or made on more or less inaccessible or unmanipulatable objects such as stars or human populations. The measurements often require specialized [[scientific instrument]]s such as [[thermometer]]s, [[Spectrometer|spectroscopes]], [[particle accelerator]]s, or [[voltmeter]]s, and the progress of a scientific field is usually intimately tied to their invention and improvement.

{{Blockquote|text=I am not accustomed to saying anything with certainty after only one or two observations.|author=[[Andreas Vesalius]] (1546)<ref>Andreas Vesalius, ''Epistola, Rationem, Modumque Propinandi Radicis Chynae Decocti'' (1546), p. 141. Quoted and translated in C.D. O'Malley, ''Andreas Vesalius of Brussels'', (1964), p. 116. As quoted by {{harvp|Bynum|Porter|2005|p=597}}: "Andreas Vesalius"</ref>}}

====Definition====
The scientific definition of a term sometimes differs substantially from its [[natural language]] usage. For example, [[mass]] and [[weight]] overlap in meaning in common discourse, but have distinct meanings in [[mechanics]]. Scientific quantities are often characterized by their [[units of measurement|units of measure]] which can later be described in terms of conventional physical units when communicating the work.

New theories are sometimes developed after realizing certain terms have not previously been sufficiently clearly defined. For example, [[Albert Einstein]]'s first paper on [[Special relativity|relativity]] begins by defining [[Relativity of simultaneity|simultaneity]] and the means for determining [[length]]. These ideas were skipped over by [[Isaac Newton]] with, "I do not define [[time in physics#Galileo: the flow of time|time]], space, place and [[motion (physics)|motion]], as being well known to all." Einstein's paper then demonstrates that they (viz., absolute time and length independent of motion) were approximations. [[Francis Crick]] cautions us that when characterizing a subject, however, it can be premature to define something when it remains ill-understood.<ref>Crick, Francis (1994), ''The Astonishing Hypothesis'' {{ISBN|0-684-19431-7}} p. 20
</ref> In Crick's study of [[consciousness]], he actually found it easier to study [[awareness]] in the [[visual system]], rather than to study [[free will]], for example. His cautionary example was the gene; the gene was much more poorly understood before Watson and Crick's pioneering discovery of the structure of DNA; it would have been counterproductive to spend much time on the definition of the gene, before them.

===Hypothesis development===
{{Main|Hypothesis formation}}
<blockquote>{{Anchor|DNA-hypotheses}}[[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] [[Linus Pauling]] proposed that DNA might be a [[triple helix]].<ref>{{harvp|McElheny|2004|p=40}}: October 1951 — "That's what a helix should look like!" Crick exclaimed in delight (This is the Cochran-Crick-Vand-Stokes theory of the transform of a helix).</ref><ref>
{{harvp|Judson|1979|p=157}}. {{"'}}The structure that we propose is a three-chain structure, each chain being a helix' – Linus Pauling"</ref> This hypothesis was also considered by [[Francis Crick]] and [[James D. Watson]] but discarded. When Watson and Crick learned of Pauling's hypothesis, they understood from existing data that Pauling was wrong.<ref>
{{harvp|McElheny|2004|pp=49–50}}: January 28, 1953 — Watson read Pauling's pre-print, and realized that in Pauling's model, DNA's phosphate groups had to be un-ionized. But DNA is an acid, which contradicts Pauling's model.
</ref> and that Pauling would soon admit his difficulties with that structure.</blockquote>

{{Anchor|Hypothesis}}A [[hypothesis]] is a suggested explanation of a phenomenon, or alternately a reasoned proposal suggesting a possible correlation between or among a set of phenomena. Normally, hypotheses have the form of a [[mathematical model]]. Sometimes, but not always, they can also be formulated as [[existential quantification|existential statements]], stating that some particular instance of the phenomenon being studied has some characteristic and causal explanations, which have the general form of [[universal quantification|universal statements]], stating that every instance of the phenomenon has a particular characteristic.

Scientists are free to use whatever resources they have – their own creativity, ideas from other fields, [[inductive reasoning]], [[Bayesian inference]], and so on – to imagine possible explanations for a phenomenon under study. {{anchor|noLogicalBridge}}Albert Einstein once observed that "there is no logical bridge between phenomena and their theoretical principles."<ref>{{cite book |last1=Einstein |first1=Albert |title=The World as I See It |date=1949 |publisher=Philosophical Library |location=New York |pages=24–28}}</ref>{{efn|name= leapIsInvolved |"A leap is involved in all thinking" —John Dewey<ref>{{harvp|Dewey|1910|p=26}}</ref> }} [[Charles Sanders Peirce]], borrowing a page from [[Aristotle]] (''[[Prior Analytics]]'', [[Inquiry#Abduction|2.25]])<ref name="aristotleAbduction">[https://en.wikisource.org/wiki/Organon_(Owen)/Prior_Analytics/Book_2#Chapter_25 Aristotle (trans. 1853) ''Prior Analytics'' 2.25] {{Webarchive|url=https://web.archive.org/web/20210910034741/https://en.wikisource.org/wiki/Organon_(Owen)/Prior_Analytics/Book_2#Chapter_25 |date=2021-09-10  }} via Wikisource</ref> described the incipient stages of [[inquiry]], instigated by the "irritation of doubt" to venture a plausible guess, as ''[[abductive reasoning]]''.<ref name="How">{{cite wikisource|title=How to Make Our Ideas Clear|first=Charles Sanders|last=Peirce|year=1877|wslink=How to Make Our Ideas Clear|volume=12|pages=286–302|journal=Popular Science Monthly}}</ref>{{rp|II,p.290}} The history of science is filled with stories of scientists claiming a "flash of inspiration", or a hunch, which then motivated them to look for evidence to support or refute their idea. [[Michael Polanyi]] made such creativity the centerpiece of his discussion of methodology.

[[William Glen (geologist and historian)|William Glen]] observes that{{sfnp|Glen|1994|pp=37–38}}

{{Blockquote|text=the success of a hypothesis, or its service to science, lies not simply in its perceived "truth", or power to displace, subsume or reduce a predecessor idea, but perhaps more in its ability to stimulate the research that will illuminate&nbsp;... bald suppositions and areas of vagueness.|author= William Glen|title= ''The Mass-Extinction Debates'' }}

In general, scientists tend to look for theories that are "[[Elegance|elegant]]" or "[[beauty|beautiful]]". Scientists often use these terms to refer to a theory that is following the known facts but is nevertheless relatively simple and easy to handle. [[Occam's Razor]] serves as a rule of thumb for choosing the most desirable amongst a group of equally explanatory hypotheses.

To minimize the [[confirmation bias]] that results from entertaining a single hypothesis, [[strong inference]] emphasizes the need for entertaining multiple alternative hypotheses,<ref name="platt">{{cite journal |last=Platt |first=John R. |author-link=John R. Platt |date=16 October 1964 |title=Strong Inference |journal=Science |volume=146 |issue=3642 |pages=347– |doi=10.1126/science.146.3642.347|pmid=17739513 |bibcode=1964Sci...146..347P }}</ref> and avoiding artifacts.<ref name= sn1987a>[[Leon Lederman]], for teaching [[physics first]], illustrates how to avoid confirmation bias: [[Ian Shelton]], in Chile, was initially skeptical that [[supernova 1987a]] was real, but possibly an artifact of instrumentation (null hypothesis), so he went outside and disproved his null hypothesis by observing SN 1987a with the naked eye. The [[Kamiokande]] experiment, in Japan, independently observed [[neutrino]]s from [[SN 1987a]] at the same time.</ref>

===Predictions from the hypothesis===
{{Further|Prediction#Science}}<blockquote>{{Anchor|DNA-predictions}}[[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] [[James D. Watson]], [[Francis Crick]], and others hypothesized that DNA had a helical structure. This implied that DNA's X-ray diffraction pattern would be 'x shaped'.<ref name="Crick pp. 137–138">{{harvp|Judson|1979|pp=137–138}}: "Watson did enough work on [[Tobacco mosaic virus]] to produce the diffraction pattern for a helix, per Crick's work on the transform of a helix."</ref><ref name="McElheny 2004 43">{{harvp|McElheny|2004|p=43}}: June 1952 — Watson had succeeded in getting X-ray pictures of TMV showing a diffraction pattern consistent with the transform of a helix.</ref> This prediction followed from the work of Cochran, Crick and Vand<ref name="HelixTransform">Cochran W, Crick FHC and Vand V. (1952) "The Structure of Synthetic Polypeptides. I. The Transform of Atoms on a Helix", ''[[Acta Crystallographica|Acta Crystallogr.]]'', '''5''', 581–586.</ref> (and independently by Stokes). The Cochran-Crick-Vand-Stokes theorem provided a mathematical explanation for the empirical observation that diffraction from helical structures produces x-shaped patterns.

In their first paper, Watson and Crick also noted that the [[double helix]] structure they proposed provided a simple mechanism for [[DNA replication]], writing, "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material".<ref>{{harvp|McElheny|2004|p=68}}: ''Nature'' April 25, 1953.</ref></blockquote>{{Anchor|Prediction}}Any useful hypothesis will enable [[prediction]]s, by [[reasoning]] including [[deductive reasoning]].{{efn|1= From the hypothesis, deduce valid forms using [[Deductive reasoning#Modus ponens|modus ponens]], or using [[Deductive reasoning#Modus tollens|modus tollens]]. Avoid invalid forms such as [[affirming the consequent]].}} It might predict the outcome of an experiment in a laboratory setting or the observation of a phenomenon in nature. The prediction can also be statistical and deal only with probabilities.

It is essential that the outcome of testing such a prediction be currently unknown. Only in this case does a successful outcome increase the probability that the hypothesis is true. If the outcome is already known, it is called a consequence and should have already been considered while [[#Hypothesis development|formulating the hypothesis]].

If the predictions are not accessible by observation or experience, the hypothesis is not yet testable and so will remain to that extent unscientific in a strict sense. A new technology or theory might make the necessary experiments feasible. For example, while a hypothesis on the existence of other intelligent species may be convincing with scientifically based speculation, no known experiment can test this hypothesis. Therefore, science itself can have little to say about the possibility. In the future, a new technique may allow for an experimental test and the speculation would then become part of accepted science.

For example, Einstein's theory of [[general relativity]] makes several specific predictions about the observable structure of [[spacetime]], such as that [[light]] bends in a [[gravitational field]], and that the amount of bending depends in a precise way on the strength of that gravitational field. [[Arthur Eddington]]'s [[Eddington experiment|observations made during a 1919 solar eclipse]] supported General Relativity rather than Newtonian [[gravitation]].<ref>In March 1917, the [[Royal Astronomical Society]] announced that on May 29, 1919, the occasion of a [[total eclipse]] of the sun would afford favorable conditions for testing Einstein's [[General theory of relativity]]. One expedition, to [[Sobral, Ceará]], [[Brazil]], and Eddington's expedition to the island of [[Principe]] yielded a set of photographs, which, when compared to photographs taken at [[Sobral, Ceará|Sobral]] and at [[Greenwich Observatory]] showed that the deviation of light was measured to be 1.69 [[arc-second]]s, as compared to Einstein's desk prediction of 1.75 [[arc-second]]s. – Antonina Vallentin (1954), ''Einstein'', as quoted by Samuel Rapport and Helen Wright (1965), ''Physics'', New York: Washington Square Press, pp. 294–295.</ref>

===Experiments===
{{Main|Experiment}}<blockquote>{{Anchor|DNA-experiments}}[[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] Watson and Crick showed an initial (and incorrect) proposal for the structure of DNA to a team from [[King's College London]] – [[Rosalind Franklin]], [[Maurice Wilkins]], and [[Raymond Gosling]]. Franklin immediately spotted the flaws which concerned the water content. Later Watson saw Franklin's [[photo 51]], a detailed X-ray diffraction image, which showed an X-shape<ref>{{cite web |title=The Secret of Photo 51 |url=https://www.pbs.org/wgbh/nova/photo51/ |url-status=live |archive-url=https://web.archive.org/web/20170831201252/http://www.pbs.org/wgbh/nova/photo51/ |archive-date=2017-08-31 |access-date=2017-09-11 |work=NOVA |publisher=PBS}}</ref><ref name=photo51Explained >[[Cynthia Wolberger]] [https://www.youtube.com/watch?v=2tMuMRY1oDo (2021) Photograph 51 explained]</ref> and was able to confirm the structure was helical.<ref name="TeaTime">{{harvp|McElheny|2004|p=52}}: Friday, January 30, 1953. Tea time — Franklin confronts Watson and his paper – "Of course it [Pauling's pre-print] is wrong. DNA is not a helix." However, Watson then visits Wilkins' office, sees [[photo 51]], and immediately recognizes the diffraction pattern of a helical structure. But additional questions remained, requiring additional iterations of their research. For example, the number of strands in the backbone of the helix (Crick suspected 2 strands, but cautioned Watson to examine that more critically), the location of the base pairs (inside the backbone or outside the backbone), etc. One key point was that they realized that the quickest way to reach a result was not to continue a mathematical analysis, but to build a physical model. Later that evening — Watson urges Wilkins to begin model-building immediately. But Wilkins agrees to do so only after Franklin's departure.</ref><ref name="Watson 1968 167">{{harvp|Watson|1968|p=167}}: "The instant I saw the picture my mouth fell open and my pulse began to race." Page 168 shows the X-shaped pattern of the B-form of [[DNA]], clearly indicating crucial details of its helical structure to Watson and Crick.</ref>{{efn|name= nextItemToSettle| The goal shifts: after observing the x-ray diffraction pattern of DNA,<ref name=TeaTime /><ref name=photo51Explained /> and as time was of the essence,<ref name=econ/> Watson and Crick realize that fastest way to discover DNA's structure was not by mathematical analysis,<ref name= reasonsFirstRule /> but by [[#DNA-iterations|building physical models]].<ref name= SameShape />}}</blockquote>
{{anchor|suitableTest|Testing|Crucial experiment}}Once predictions are made, they can be sought by experiments. If the test results contradict the predictions, the hypotheses which entailed them are called into question and become less tenable. Sometimes the experiments are conducted incorrectly or are not very well designed when compared to a [[crucial experiment]]. If the experimental results confirm the predictions, then the hypotheses are considered more likely to be correct, but might still be wrong and continue to be subject to [[#Evaluation and improvement|further testing.]] The [[experimental control]] is a technique for dealing with observational error. This technique uses the contrast between multiple samples, or observations, or populations, under differing conditions, to see what varies or what remains the same. We vary the conditions for the acts of measurement, to help isolate what has changed. [[Mill's canons]] can then help us figure out what the important factor is.<ref>[[John Stuart Mill|Mill, John Stuart]], "A System of Logic", University Press of the Pacific, Honolulu, 2002, {{ISBN|1-4102-0252-6}}.</ref> [[Factor analysis]] is one technique for discovering the important factor in an effect.

Depending on the predictions, the experiments can have different shapes. It could be a classical experiment in a laboratory setting, a [[double-blind]] study or an archaeological [[excavation (archaeology)|excavation]]. Even taking a plane from [[New York City|New York]] to [[Paris]] is an experiment that tests the [[aerodynamics|aerodynamical]] hypotheses used for constructing the plane.

These institutions thereby reduce the research function to a cost/benefit,<ref name="conjugatePairs" /> which is expressed as money, and the time and attention of the researchers to be expended,<ref name="conjugatePairs" /> in exchange for a report to their constituents.<ref name="nsf">National Science Foundation (NSF)  (2021) [https://www.nsf.gov/oig/reports/ NSF Reports] {{Webarchive|url=https://web.archive.org/web/20210817165231/https://www.nsf.gov/oig/reports/|date=2021-08-17}} and [https://www.nsf.gov/news/ News] {{Webarchive|url=https://web.archive.org/web/20210820162008/https://www.nsf.gov/news/|date=2021-08-20}}</ref> Current large instruments, such as CERN's [[Large Hadron Collider]] (LHC),<ref name="lhc">{{Cite web |title=LHC long term schedule |url=https://lhc-commissioning.web.cern.ch/lhc-commissioning/schedule/LHC-long-term.htm |url-status=live |archive-url=https://web.archive.org/web/20200425105121/https://lhc-commissioning.web.cern.ch/lhc-commissioning/schedule/LHC-long-term.htm |archive-date=2020-04-25 |access-date=2021-08-22 |website=lhc-commissioning.web.cern.ch}} (2021)</ref> or [[LIGO]],<ref name="ligo">{{cite web |title=ligo.caltech.edu (1999) Laser Interferometer Gravitational-Wave Observatory |url=https://www.ligo.caltech.edu/ |url-status=live |archive-url=https://web.archive.org/web/20210901125538/https://www.ligo.caltech.edu/ |archive-date=2021-09-01 |access-date=2021-08-30}}</ref> or the [[National Ignition Facility]] (NIF),<ref name="nif">{{cite web |title=NIF (2021) What Is the National Ignition Facility? |url=https://lasers.llnl.gov/about/what-is-nif |url-status=live |archive-url=https://web.archive.org/web/20170731064919/https://lasers.llnl.gov/about/what-is-nif |archive-date=2017-07-31 |access-date=2021-08-22}}</ref> or the [[International Space Station]] (ISS),<ref name="iss">{{cite web |date=12 January 2015 |title=ISS (2021) International Space Station |url=https://www.nasa.gov/mission_pages/station/main/index.html |url-status=live |archive-url=https://web.archive.org/web/20050907073730/http://www.nasa.gov/mission_pages/station/main/index.html |archive-date=2005-09-07 |access-date=2021-08-22}}</ref> or the [[James Webb Space Telescope]] (JWST),<ref name="jwst">{{cite web |title=JWST (2021) WEBB Space Telescope |url=https://www.jwst.nasa.gov/ |url-status=live |archive-url=https://web.archive.org/web/20120104225155/http://www.jwst.nasa.gov/ |archive-date=2012-01-04 |access-date=2021-08-22}}</ref><ref name="jwstDeploymentSeq">James Webb Space Telescope (JWST) [https://www.youtube.com/watch?v=RzGLKQ7_KZQ (12 Nov 2021) James Webb Space Telescope Deployment Sequence (Nominal)] {{Webarchive|url=https://web.archive.org/web/20211223035530/https://www.youtube.com/watch?v=RzGLKQ7_KZQ|date=2021-12-23}} highlights the predictions from launch to day+29,</ref> entail expected costs of billions of dollars, and timeframes extending over decades. These kinds of institutions affect public policy, on a national or even international basis, and the researchers would require shared access to such machines and their [[#otherScientists|adjunct infrastructure]].{{efn-lg|name= feedTheMachinery| The machinery of the mind can only transform knowledge, but never originate it, unless it be fed with facts of observation. —[[C.S. Peirce]]<ref name= How/>}}<ref name="Crutchfield" >{{cite web|url=http://csc.ucdavis.edu/~chaos/chaos/talks/CSTheorySFIRetreat.pdf|title=James Crutchfield (2003) "Complex Systems Theory?"|access-date=2018-05-27 |archive-date=2021-04-18 |archive-url=https://web.archive.org/web/20210418204840/http://csc.ucdavis.edu/~chaos/chaos/talks/CSTheorySFIRetreat.pdf|url-status=live}}</ref>

{{anchor|ethicalPosition}}Scientists assume an attitude of openness and accountability on the part of those experimenting. Detailed record-keeping is essential, to aid in recording and reporting on the experimental results, and supports the effectiveness and integrity of the procedure. They will also assist in reproducing the experimental results, likely by others. Traces of this approach can be seen in the work of [[Hipparchus]] (190–120 BCE), when determining a value for the precession of the Earth, while [[Scientific control|controlled experiments]] can be seen in the works of [[Muhammad ibn Jābir al-Harrānī al-Battānī|al-Battani]] (853–929 CE)<ref>[[Muhammad ibn Jābir al-Harrānī al-Battānī|al-Battani]], ''De Motu Stellarum'' [[Latin translations of the 12th century|translation from Arabic to Latin in 1116]], as cited by E. S. Kennedy, ''A Survey of Islamic Astronomical Tables,'' (Transactions of the American Philosophical Society, New Series, 46, 2), Philadelphia, 1956, pp. 10–11, 32–34.</ref> and [[#alhazen|Alhazen]] (965–1039 CE).{{sfnp|Smith|2001b}}{{efn|''[[Book of Optics]]'' Book II [3.52] to [3.66]  Summary p.444 for Alhazen's experiments on color; pp.343—394 for his physiological experiments on the eye{{sfnp|Smith|2001b}} }}{{efn|name= straightLinesOnly |''[[Book of Optics]]'' Book Seven, Chapter Two [2.1] p.220: — light travels through transparent bodies, such as air, water, glass, transparent stones, in straight lines. "Indeed, this is observable by means of experiment".<ref name= smith2010 >{{harvp|Smith|2010|p=220}} Book Seven covers refraction.</ref> }}

===Communication and iteration===

{{See also|Scientific literature|Scholarly communication}}

<blockquote>
{{Anchor|DNA-iterations}}[[File:DNA icon.svg|frameless|22x22px|link=|alt=DNA label]] Watson and Crick then produced their model, using this information along with the previously known information about DNA's composition, especially Chargaff's rules of base pairing.<ref name="SameShape">{{harvp|McElheny|2004|pp=57–59}}: Saturday, February 28, 1953 — Watson found the base-pairing mechanism which explained [[Chargaff's rules]] using his cardboard models.</ref> After considerable fruitless experimentation, being discouraged by their superior from continuing, and numerous false starts,<ref>{{harvp|McElheny|2004|p=53}}: The weekend (January 31 – February 1) — After seeing photo 51, Watson informed Bragg of the X-ray diffraction image of DNA in B form. Bragg permitted them to restart their research on DNA (that is, model building).</ref><ref>{{harvp|McElheny|2004|p=54}}: Sunday, February 8, 1953 — Maurice Wilkes gave Watson and Crick permission to work on models, as Wilkes would not be building models until Franklin left DNA research.</ref><ref>{{harvp|McElheny|2004|p=56}}: [[Jerry Donohue]], on sabbatical from Pauling's lab and visiting Cambridge, advises Watson that the textbook form of the base pairs was incorrect for DNA base pairs; rather, the keto form of the base pairs should be used instead. This form allowed the bases' hydrogen bonds to pair 'unlike' with 'unlike', rather than to pair 'like' with 'like', as Watson was inclined to model, based on the textbook statements. On February 27, 1953, Watson was convinced enough to make cardboard models of the nucleotides in their keto form.</ref> Watson and Crick were able to infer the essential structure of [[DNA]] by concrete [[model (abstract)|modeling]] [[DNA#History|of the physical shapes]] of the [[nucleotide]]s which comprise it.<ref name="SameShape" /><ref>
{{harvp|Watson|1968|pp=194–197}}: "Suddenly I became aware that an [[adenine]]-[[thymine]] pair held together by two [[hydrogen bond]]s was identical in shape to a [[guanine]]-[[cytosine]] pair held together by at least two hydrogen bonds.&nbsp;..."</ref><ref>
{{harvp|McElheny|2004|p=57}}: Saturday, February 28, 1953 — Watson tried 'like with like' and admitted these base pairs didn't have hydrogen bonds that line up. But after trying 'unlike with unlike', and getting [[Jerry Donohue]]'s approval, the base pairs turned out to be identical in shape (as Watson stated above in his 1968 ''Double Helix'' memoir quoted above). Watson now felt confident enough to inform Crick. (Of course, 'unlike with unlike' increases the number of possible [[codon]]s, if this scheme were a [[genetic code]].)
</ref> They were guided by the bond lengths which had been deduced by [[Linus Pauling]] and by [[Rosalind Franklin]]'s X-ray diffraction images.
</blockquote>

{{Anchor|Analysis}}The scientific method is iterative. At any stage, it is possible to refine its [[accuracy and precision]], so that some consideration will lead the scientist to repeat an earlier part of the process. Failure to develop an interesting hypothesis may lead a scientist to re-define the subject under consideration. Failure of a hypothesis to produce interesting and testable predictions may lead to reconsideration of the hypothesis or of the definition of the subject. Failure of an experiment to produce interesting results may lead a scientist to reconsider the experimental method, the hypothesis, or the definition of the subject.

{{anchor|alhazen}}This manner of iteration can span decades and sometimes centuries. [[Academic publishing#Types of academic paper|Published papers]] can be built upon. For example: By 1027, [[Alhazen]], based on his measurements of the [[refraction]] of light, was able to deduce that [[outer space]] was less dense than [[air]], that is: "the body of the heavens is rarer than the body of air".<ref name="alhacenOnRefraction4.28">{{harvp|Smith|2010}} Book 7, [4.28] p.270</ref> In 1079 [[Ibn Mu'adh al-Jayyani|Ibn Mu'adh]]'s ''Treatise On Twilight'' was able to infer that Earth's atmosphere was 50 miles thick, based on [[atmospheric refraction]] of the sun's rays.{{efn|name= crepusculis|1= The Sun's rays are still visible at [[twilight]] in the morning and evening due to atmospheric refraction even when the depression angle of the sun is 18° below the horizon.<ref name= brGoldstein >Goldstein, Bernard R. (1977) [[Ibn Mu'adh al-Jayyani|Ibn Mu'adh]]'s "[https://www.jstor.org/stable/41133483 (1079) Treatise On Twilight and the Height of the Atmosphere] {{Webarchive|url=https://web.archive.org/web/20220921011840/https://www.jstor.org/stable/41133483 |date=2022-09-21  }}" ''[[Archive for History of Exact Sciences]]'' Vol. '''17''', No. 2 (21.VII.1977), pp. 97-118 (22 pages) JSTOR. (''Treatise On Twilight'' was printed by F Risner in ''Opticae Thesaurus'' (1572) as ''Liber de crepusculis'', but attributed to Alhazen rather than Ibn Mu'adh.)</ref> }}

This is why the scientific method is often represented as circular – new information leads to new characterisations, and the cycle of science continues. Measurements collected [[Research data archiving| can be archived]], passed onwards and used by others. {{anchor|otherScientists}}Other scientists may start their own research and [[#aGuideline |enter the process]] at any stage. They might adopt the characterization and formulate their own hypothesis, or they might adopt the hypothesis and deduce their own predictions. Often the experiment is not done by the person who made the prediction, and the characterization is based on experiments done by someone else. Published results of experiments can also serve as a hypothesis predicting their own reproducibility.

===Confirmation<!--Linked from [[Confirmation (disambiguation)]]-->===
{{Main|Reproducibility}}
Science is a social enterprise, and scientific work tends to be accepted by the scientific community when it has been confirmed. Crucially, experimental and theoretical results must be reproduced by others within the scientific community. Researchers have given their lives for this vision; [[Georg Wilhelm Richmann]] was killed by [[ball lightning]] (1753) when attempting to replicate the 1752 kite-flying experiment of [[Benjamin Franklin]].<ref>{{cite journal |last=Krider |first=E. Philip |date=Jan 2006 |title=Benjamin Franklin and lightning rods |journal=Physics Today |volume=59 |issue=1 |page=42 |doi=10.1063/1.2180176 |bibcode=2006PhT....59a..42K |s2cid=110623159 |quote=On 6 August 1753, the Swedish scientist Georg Wilhelm Richmann was electrocuted in St. Petersburg ...|doi-access=free }}</ref>

{{anchor|Evaluation and improvement}}If an experiment cannot be [[Reproducibility|repeated]] to produce the same results, this implies that the original results might have been in error. As a result, it is common for a single experiment to be performed multiple times, especially when there are uncontrolled variables or other indications of [[Observational error|experimental error]]. For significant or surprising results, other scientists may also attempt to replicate the results for themselves, especially if those results would be important to their own work.<ref>{{cite web |title=Reconstruction of Galileo Galilei's experiment – the inclined plane |url=http://www.fyysika.ee/vorgustik/wp-content/uploads/2011/11/Reconstruction-of-Galileo-Galilei.pdf |url-status=live |archive-url=https://web.archive.org/web/20140429075745/http://www.fyysika.ee/vorgustik/wp-content/uploads/2011/11/Reconstruction-of-Galileo-Galilei.pdf |archive-date=2014-04-29 |access-date=2014-04-28}}</ref> Replication has become a contentious issue in social and biomedical science where treatments are administered to groups of individuals. Typically an ''experimental group'' gets the treatment, such as a drug, and the ''control group'' gets a placebo. [[John Ioannidis]] in 2005 pointed out that the method being used has led to many findings that cannot be replicated.<ref>{{cite journal |last=Ioannidis |first=John P. A. |date=August 2005 |title=Why most published research findings are false |journal=[[PLOS Medicine]] |volume=2 |issue=8 |pages=e124 |doi=10.1371/journal.pmed.0020124 |pmc=1182327 |pmid=16060722 |doi-access=free}}</ref>

The process of [[peer review]] involves the evaluation of the experiment by experts, who typically give their opinions anonymously. Some journals request that the experimenter provide lists of possible peer reviewers, especially if the field is highly specialized. Peer review does not certify the correctness of the results, only that, in the opinion of the reviewer, the experiments themselves were sound (based on the description supplied by the experimenter). If the work passes peer review, which occasionally may require new experiments requested by the reviewers, it will be published in a peer-reviewed [[Academic journal|scientific journal]]. The specific journal that publishes the results indicates the perceived quality of the work.{{efn|In ''Two New Sciences'', there are three 'reviewers': Simplicio, Sagredo, and Salviati, who serve as foil, antagonist, and protagonist. Galileo speaks for himself only briefly. But Einstein's 1905 papers were not peer-reviewed before their publication.}}

Scientists typically are careful in recording their data, a requirement promoted by [[Ludwik Fleck]] (1896–1961) and others.{{sfnp|Fleck|1979|pp=xxvii–xxviii}} Though not typically required, they might be requested to [[Data sharing|supply this data]] to other scientists who wish to replicate their original results (or parts of their original results), extending to the sharing of any experimental samples that may be difficult to obtain.<ref>"[http://grants.nih.gov/grants/policy/data_sharing/index.htm NIH Data Sharing Policy] {{Webarchive|url=https://web.archive.org/web/20120513171213/http://grants.nih.gov/grants/policy/data_sharing/index.htm|date=2012-05-13}}."</ref> To protect against bad science and fraudulent data, government research-granting agencies such as the [[National Science Foundation]], and science journals, including ''Nature'' and ''Science'', have a policy that researchers must archive their data and methods so that other researchers can test the data and methods and build on the research that has gone before. [[Scientific data archiving]] can be done at several national archives in the U.S. or the [[World Data Center]].

== Foundational principles ==
=== Honesty, openness, and falsifiability ===
{{See also|Scientific integrity|Open science}}

The unfettered principles of science are to strive for accuracy and the creed of honesty; openness already being a matter of degrees. Openness is restricted by the general rigour of scepticism. And of course the matter of non-science.

Smolin, in 2013, espoused ethical principles rather than giving any potentially limited definition of the rules of inquiry.{{efn-lg|name= ethicalPosition}} His ideas stand in the context of the scale of data–driven and [[big science]], which has seen increased importance of honesty and consequently [[reproducibility]]. His thought is that science is a community effort by those who have accreditation and are working within the [[Scientific community|community]]. He also warns against overzealous parsimony. 

Popper previously took ethical principles even further, going as far as to ascribe value to theories only if they were falsifiable. Popper used the falsifiability criterion to demarcate a scientific theory from a theory like astrology: both "explain" observations, but the scientific theory takes the risk of making predictions that decide whether it is right or wrong:<ref name=Popper0>
{{cite book |author=Karl Raimund Popper |title=The logic of scientific discovery |url=https://books.google.com/books?id=T76Zd20IYlgC&q=%22It+must+be+possible+for+an+empirical+scientific+system+to+be+refuted+by+experience%22&pg=PA18 |pages= 18, 280 |isbn=0415278430|publisher=Routledge/Taylor & Francis Group |year=2002 |edition=Reprint of translation of 1935 ''Logik der Forschung''}}
</ref><ref name=Popper1>
{{cite web |title=Science: Conjectures and refutations |author=Karl Popper |url=http://worthylab.tamu.edu/courses_files/popper_conjecturesandrefutations.pdf |archive-url=https://web.archive.org/web/20130909021911/http://worthylab.tamu.edu/courses_files/popper_conjecturesandrefutations.pdf |url-status=dead |archive-date=2013-09-09 |publisher=Texas A&M University The motivation & cognition interface lab |access-date=2013-01-22 }} This lecture by Popper was first published as part of the book ''Conjectures and Refutations'' and is linked [http://worthylab.tamu.edu/Courses.html here].
</ref>

{{quote|"Those among us who are unwilling to expose their ideas to the hazard of refutation do not take part in the game of science."
|Karl Popper|''The Logic of Scientific Discovery (2002 [1935])''}}

=== Theory's interactions with observation ===

{{Anchor|th-v-obs}}Science has limits. Those limits are usually deemed to be answers to questions that aren't in science's domain, such as faith. Science has other limits as well, as it seeks to make true statements about reality.{{sfnp|Gauch Jr|2002|loc=ch. 1}} The nature of [[truth]] and the discussion on how scientific statements relate to reality is best left to the article on the [[philosophy of science]] here. More immediately topical limitations show themselves in the observation of reality.

[[File:PositronDiscovery.png|thumb|220px|This [[cloud chamber]] photograph is the first observational evidence of [[positron]]s, 2 August 1932; interpretable only through prior theory.<ref name="Anderson 1933 pp. 491–494">{{cite journal | last=Anderson | first=Carl D. | title=The Positive Electron | journal=Physical Review | volume=43 | issue=6 | date=15 March 1933 | issn=0031-899X | doi=10.1103/PhysRev.43.491 | pages=491–494| bibcode=1933PhRv...43..491A }}<!--credit:[[c:File:PositronDiscovery.png]]--></ref>]]

It is the natural limitations of scientific inquiry that there is no pure observation as theory is required to interpret empirical data, and observation is therefore influenced by the observer's conceptual framework.<ref name="Hanson1958"/> As science is an unfinished project, this does lead to difficulties. Namely, that false conclusions are drawn, because of limited information.

An example here are the experiments of Kepler and Brahe, used by Hanson to illustrate the concept. Despite observing the same sunrise the two scientists came to different conclusions—their [[intersubjectivity]] leading to differing conclusions. [[Johannes Kepler]] used [[Tycho Brahe]]'s method of observation, which was to project the image of the Sun on a piece of paper through a pinhole aperture, instead of looking directly at the Sun. He disagreed with Brahe's conclusion that total eclipses of the Sun were impossible because, contrary to Brahe, he knew that there were historical accounts of total eclipses. Instead, he deduced that the images taken would become more accurate, the larger the aperture—this fact is now fundamental for optical system design.{{efn|name= Kepler1604 }} Another historic example here is the [[discovery of Neptune]], credited as being found via mathematics because previous observers didn't know what they were looking at.<ref name="Lequeux 2021 pp. 159–183">{{cite book | last=Lequeux | first=James | title=Neptune: From Grand Discovery to a World Revealed | chapter=Urbain Jean Joseph Le Verrier: Predictions Leading to Discovery | series=Historical & Cultural Astronomy | publisher=Springer International Publishing | publication-place=Cham | year=2021 | isbn=978-3-030-54217-7 | issn=2509-310X | doi=10.1007/978-3-030-54218-4_5 | pages=159–183}}</ref>

=== Empiricism, rationalism, and more pragmatic views ===

Scientific endeavour can be characterised as the pursuit of truths about the natural world or as the elimination of doubt about the same. The former is the direct construction of explanations from empirical data and logic, the latter the reduction of potential explanations.{{efn-lg|"At the heart of science is an essential balance between two seemingly contradictory attitudes—an openness to new ideas, no matter how bizarre or counterintuitive, and the most ruthlessly skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense." — [[Carl Sagan]]<ref>{{cite book | last=Sagan | first=Carl | title=The Demon-Haunted World | date=1995 | author-link=Carl Sagan | title-link=The Demon-Haunted World}}<!--credit to q:Science--></ref>}} It was established [[#th-v-obs|above]] how the interpretation of empirical data is theory-laden, so neither approach is trivial.

The ubiquitous element in the scientific method is [[empiricism]], which holds that knowledge is created by a process involving observation; scientific theories generalize observations. This is in opposition to stringent forms of [[rationalism]], which holds that knowledge is created by the human intellect; later clarified by Popper to be built on prior theory.{{sfnp|Godfrey-Smith|2003|pp=19-74}} The scientific method embodies the position that reason alone cannot solve a particular scientific problem; it unequivocally refutes claims that [[revelation]], political or religious [[dogma]], appeals to tradition, commonly held beliefs, common sense, or currently held theories pose the only possible means of demonstrating truth.<ref name= truthSought4sake /><ref name="reasonsFirstRule">{{cite book |last=Peirce |first=Charles S. |title=Collected Papers |year=1899 |series=v. 1 |at=paragraphs 135–140 |chapter=F.R.L. [First Rule of Logic] |quote=...&nbsp;in order to learn, one must desire to learn&nbsp;... |access-date=2012-01-06 |chapter-url=http://www.princeton.edu/~batke/peirce/frl_99.htm |archive-url=https://web.archive.org/web/20120106071421/http://www.princeton.edu/~batke/peirce/frl_99.htm |archive-date=January 6, 2012 |url-status=dead}}</ref>

In 1877,<ref name="Fixation" /> [[C. S. Peirce]] characterized inquiry in general not as the pursuit of truth ''per se'' but as the struggle to move from irritating, inhibitory doubts born of surprises, disagreements, and the like, and to reach a secure belief, the belief being that on which one is prepared to act. His [[Pragmatism|pragmatic]] views framed scientific inquiry as part of a broader spectrum and as spurred, like inquiry generally, by actual doubt, not mere verbal or "hyperbolic doubt", which he held to be fruitless.{{efn|1="What one does not in the least doubt one should not pretend to doubt; but a man should train himself to doubt," said Peirce in a brief intellectual autobiography.<ref>{{cite book |contributor-last=Ketner |contributor-first=Kenneth Laine |year=2009 |contribution=Charles Sanders Peirce: Interdisciplinary Scientist |last=Peirce |first=Charles S. |editor-last=Bisanz |editor-first=Elize |title=The Logic of Interdisciplinarity |publisher=Akademie Verlag |place=Berlin}}</ref> Peirce held that actual, genuine doubt originates externally, usually in surprise, but also that it is to be sought and cultivated, "provided only that it be the weighty and noble metal itself, and no counterfeit nor paper substitute".<ref>{{cite magazine |last=Peirce |first=Charles S. |date=October 1905 |title=Issues of Pragmaticism |magazine=The Monist |volume=XV |number=4 |pages=481–499, see [https://archive.org/stream/monistquart15hegeuoft#page/484/mode/1up p. 484], and [https://archive.org/stream/monistquart15hegeuoft#page/491/mode/1up p. 491]}} Reprinted in ''Collected Papers'' v. 5, paragraphs 438–463, see 443 and 451.</ref>}} This "hyperbolic doubt" Peirce argues against here is of course just another name for [[Cartesian doubt]] associated with [[René Descartes]]. It is a methodological route to certain knowledge by identifying what can't be doubted.

A strong formulation of the scientific method is not always aligned with a form of [[empiricism]] in which the empirical data is put forward in the form of experience or other abstracted forms of knowledge as in current scientific practice the use of [[scientific modelling]] and reliance on abstract typologies and theories is normally accepted. In 2010, [[Stephen Hawking|Hawking]] suggested that physics' models of reality should simply be accepted where they prove to make useful predictions. He calls the concept [[model-dependent realism]].<ref name="Hawking"/>

==Rationality==
Rationality embodies the essence of sound reasoning, a cornerstone not only in philosophical discourse but also in the realms of science and practical decision-making. According to the traditional viewpoint, rationality serves a dual purpose: it governs beliefs, ensuring they align with logical principles, and it steers actions, directing them towards coherent and beneficial outcomes. This understanding underscores the pivotal role of reason in shaping our understanding of the world and in informing our choices and behaviours.{{sfnp|Gauch Jr|2002|pp=29-31}} The following section will first explore beliefs and biases, and then get to the rational reasoning most associated with the sciences. 

===Beliefs and biases===
{{multiple image
 | align = right
 | direction = vertical
 | width = 220
 | image1 = Jean Louis Théodore Géricault 001.jpg
 | caption1 = Flying gallop as shown by this painting ([[Théodore Géricault]], 1821) is [[Falsifiability|falsified]]; see below.
 | image2 = The Horse in Motion high res.jpg
 | caption2 = [[Sallie Gardner at a Gallop|Muybridge's photographs]] of ''The Horse in Motion'', 1878, were used to answer the question of whether all four feet of a galloping horse are ever off the ground at the same time. This demonstrates a use of photography as an experimental tool in science.
}}

Scientific methodology often directs that [[Hypothesis|hypotheses]] be tested in [[Scientific control|controlled]] conditions wherever possible. This is frequently possible in certain areas, such as in the biological sciences, and more difficult in other areas, such as in astronomy.

The practice of experimental control and reproducibility can have the effect of diminishing the potentially harmful effects of circumstance, and to a degree, personal bias. For example, pre-existing beliefs can alter the interpretation of results, as in [[confirmation bias]]; this is a [[heuristic]] that leads a person with a particular belief to see things as reinforcing their belief, even if another observer might disagree (in other words, people tend to observe what they expect to observe).<ref name="beliefCreatesReality">{{cite book | chapter-url=https://doi.org/10.1016/S0065-2601(08)60146-X | doi=10.1016/S0065-2601(08)60146-X | chapter=When Belief Creates Reality | title=Advances in Experimental Social Psychology Volume 18 | date=1984 | last1=Snyder | first1=Mark | volume=18 | pages=247–305 | isbn=978-0-12-015218-6 }}</ref>

{{Blockquote|text=[T]he action of thought is excited by the irritation of doubt, and ceases when belief is attained.|author=[[C.S. Peirce]]|source=''How to Make Our Ideas Clear'' (1877)<ref name= How/>}}

A historical example is the belief that the legs of a [[Horse gallop|galloping]] horse are splayed at the point when none of the horse's legs touch the ground, to the point of this image being included in paintings by its supporters. However, the first stop-action pictures of a horse's gallop by [[Eadweard Muybridge]] showed this to be false, and that the legs are instead gathered together.<ref>{{harvp|Needham |Wang|1954|p=166}} shows how the 'flying gallop' image propagated from China to the West.</ref>

Another important human bias that plays a role is a preference for new, surprising statements (see ''[[Appeal to novelty]]''), which can result in a search for evidence that the new is true.{{sfnp|Goldhaber|Nieto|2010|page=940}} Poorly attested beliefs can be believed and acted upon via a less rigorous heuristic.<ref name= mythIsAbelief >Ronald R. Sims (2003). ''Ethics and corporate social responsibility: Why giants fall.'' p. 21: {{"'}}A myth is a belief given uncritical acceptance by members of a group ...' – Weiss, ''Business Ethics'' p. 15."</ref>

{{anchor|robustTheory}}Goldhaber and Nieto published in 2010 the observation that if theoretical structures with "many closely neighboring subjects are described by connecting theoretical concepts, then the theoretical structure acquires a robustness which makes it increasingly hard{{snd}}though certainly never impossible{{snd}}to overturn".{{sfnp|Goldhaber|Nieto|2010|page=942}} When a narrative is constructed its elements become easier to believe.{{sfnp|Lakatos|1976|pp=1—19}}<ref name= narrativeFallacy >{{harvp|Taleb|2007|p=72}} lists ways to avoid the narrative fallacy and confirmation bias; the narrative fallacy being a substitute for explanation.</ref>

{{anchor|genesisOfScientificFact}}{{harvp|Fleck|1979|p=27}} notes "Words and ideas are originally phonetic and mental equivalences of the experiences coinciding with them. ... Such proto-ideas are at first always too broad and insufficiently specialized. ... Once a structurally complete and closed system of opinions consisting of many details and relations has been formed, it offers enduring resistance to anything that contradicts it". Sometimes, these relations have their elements assumed ''[[A priori and a posteriori|a priori]]'', or contain some other logical or methodological flaw in the process that ultimately produced them. [[Donald M. MacKay]] has analyzed these elements in terms of limits to the accuracy of measurement and has related them to instrumental elements in a category of measurement.{{efn-lg|name= macKay| 1=The scientific method requires testing and validation [[Empirical evidence|''a posteriori'']] before ideas are accepted.<ref name= conjugatePairs>{{cite book |quote=Invariably one came up against fundamental physical limits to the accuracy of measurement. ... The art of physical measurement seemed to be a matter of compromise, of choosing between reciprocally related uncertainties. ... Multiplying together the conjugate pairs of uncertainty limits mentioned, however, I found that they formed invariant products of not one but two distinct kinds. ... The first group of limits were calculable ''a priori'' from a specification of the instrument. The second group could be calculated only ''a posteriori'' from a specification of what was ''done'' with the instrument. ... In the first case each unit [of information] would add one additional ''dimension'' (conceptual category), whereas in the second each unit would add one additional ''atomic fact''. |pages=1–4 |last=MacKay |first=Donald M. |year=1969 |title=Information, Mechanism, and Meaning |place=Cambridge, MA |publisher=MIT Press |isbn=0-262-63032-X}}
</ref>}}

=== Deductive and inductive reasoning{{anchor|i&d}} ===
{{Main|Deductive reasoning|Inductive reasoning}}

The idea of there being two opposed justifications for truth has shown up through-out the history of scientific method as analysis versus synthesis, non-ampliative/ampliative, or even confirmation and verification. (And there are other kinds of reasoning.) One to use what is observed to build towards fundamental truths – and the other to derive from those fundamental truths more specific principles.<ref name="SEP_SM">{{cite web | last1=Hepburn | first1=Brian | last2=Andersen | first2=Hanne | title=Scientific Method | website=Stanford Encyclopedia of Philosophy | date=13 November 2015 | url=https://plato.stanford.edu/archives/sum2021/entries/scientific-method | access-date=21 April 2024}}</ref>

Deductive reasoning is the building of knowledge based on what has been shown to be true before. It requires the assumption of fact established prior, and, given the truth of the assumptions, a valid deduction guarantees the truth of the conclusion. Inductive reasoning builds knowledge not from established truth, but from a body of observations. It requires stringent scepticism regarding observed phenomena, because cognitive assumptions can distort the interpretation of initial perceptions.<ref name="Gauch Jr 2002 p30/ch4"/>

[[File:Perihelio.svg|right|thumb|[[Apsidal precession|Precession]] of the [[Perihelion and aphelion|perihelion]]{{snd}}exaggerated in the case of Mercury, but observed in the case of [[S2 (star)|S2]]'s [[apsidal precession]] around [[Sagittarius A*]]<ref>{{cite web |date=16 April 2020 |title=ESO Telescope Sees Star Dance Around Supermassive Black Hole, Proves Einstein Right |url=https://www.eso.org/public/news/eso2006/ |url-status=live |archive-url=https://web.archive.org/web/20200515210420/https://www.eso.org/public/news/eso2006/ |archive-date=2020-05-15 |access-date=2020-04-17 |work=Science Release |publisher=[[European Southern Observatory]]}}</ref>]]

[[File:Inductive Deductive Reasoning.svg|thumb|Inductive Deductive Reasoning]]

{{anchor|precession of Mercury}}An example for how inductive and deductive reasoning works can be found in the [[history of gravitational theory]].{{efn|The philosophy of knowledge arising through observation is also called [[inductivism]]. A radical proponent of this approach to knowledge was [[John Stuart Mill]] who took all knowledge – even mathematical knowledge – to arise from experience through induction. The inductivist approach is still common place, though Mill's extreme views are outdated today.<ref name="Psillos 2013">{{cite book | last=Psillos | first=Stathis | title=Reason and Rationality | chapter=1. Reason and Science | publisher=DE GRUYTER | date=2013-12-31 | isbn=978-3-11-032514-0 | doi=10.1515/9783110325867.33 | pages=33–52}}</ref>{{rp|35}}}} It took thousands of years of measurements, from the [[Chaldea]]n, [[India]]n, [[History of Iran|Persian]], [[Greece|Greek]], [[Arabs|Arabic]], and [[Ethnic groups in Europe|European]] astronomers, to fully record the motion of planet [[Earth]].{{efn|name=Astronomy101 |1= [[Hipparchus]] used his own observations of the stars, as well as the observations by Chaldean and Babylonian astronomers to estimate Earth's precession.<ref name=astron101 >Brad Snowder's Astronomy Pages [https://astro101.wwu.edu/a101_precession.html ( Precession of the Equinox]</ref>}} [[Johannes Kepler|Kepler ]](and others) were then able to build their early theories by [[Inductive reasoning#inductive generalization|generalizing the collected data inductively]], and [[Isaac Newton|Newton]] was able to unify prior theory and measurements into the consequences of his [[Newton's laws of motion|laws of motion]] in 1727.{{efn|name= keplerNewton |1= Isaac Newton (1727) [[Philosophiæ Naturalis Principia Mathematica#Book 3, De mundi systemate|On the System of the World]] condensed Kepler's law of for the planetary motion of Mars, Galileo's law of falling bodies, the motion of the planets of the Solar system, etc. into consequences of his three laws of motion.<ref name= systOfWorld >[[Isaac Newton]] (1727) [[Philosophiæ Naturalis Principia Mathematica#Book 3, De mundi systemate|On the System of the World]]</ref> ''See Motte's translation ([https://en.wikisource.org/wiki/The_Mathematical_Principles_of_Natural_Philosophy_(1846)/The_System_of_the_World 1846])''}} 

Another common example of inductive reasoning is the observation of a [[counterexample]] to current theory inducing the need for new ideas. [[Urbain Le Verrier|Le Verrier]] in 1859 pointed out problems with the [[Perihelion and aphelion|perihelion]] of [[Mercury (planet)|Mercury]] that showed Newton's theory to be at least incomplete. The observed difference of Mercury's [[Apsidal precession|precession]] between Newtonian theory and observation was one of the things that occurred to [[Albert Einstein|Einstein]] as a possible early test of his [[theory of relativity]]. His relativistic calculations matched observation much more closely than Newtonian theory did.{{efn|name=LeVerrier1859 |1=The difference is approximately 43 arc-seconds per century. And the precession of Mercury's orbit is cited in [[Tests of general relativity]]: U. Le Verrier (1859), (in French), [https://archive.org/stream/comptesrendusheb49acad#page/378/mode/2up "Lettre de M. Le Verrier à M. Faye sur la théorie de Mercure et sur le mouvement du périhélie de cette planète"], Comptes rendus hebdomadaires des séances de l'Académie des sciences (Paris), vol. 49 (1859), pp.379–383.}} Though, today's [[Standard Model]] of physics suggests that we still do not know at least some of the concepts surrounding Einstein's theory, it holds to this day and is being built on deductively. 

A theory being assumed as true and subsequently built on is a common example of deductive reasoning. Theory building on Einstein's achievement can simply state that 'we have shown that this case fulfils the conditions under which general/special relativity applies, therefore its conclusions apply also'. If it was properly shown that 'this case' fulfils the conditions, the conclusion follows. An extension of this is the assumption of a solution to an open problem. This weaker kind of deductive reasoning will get used in current research, when multiple scientists or even teams of researchers are all gradually solving specific cases in working towards proving a larger theory. This often sees hypotheses being revised again and again as new proof emerges.

This way of presenting inductive and deductive reasoning shows part of why science is often presented as being a cycle of iteration. It is important to keep in mind that that cycle's foundations lie in reasoning, and not wholly in the following of procedure.

===Certainty, probabilities, and statistical inference===

Claims of scientific truth can be opposed in three ways: by falsifying them, by questioning their certainty, or by asserting the claim itself to be incoherent.{{efn| ...simplified and (post-modern) philosophy notwithstanding.{{harvp|Gauch Jr|2002|p=33}}}} Incoherence, here, means internal errors in logic, like stating opposites to be true; falsification is what Popper would have called the honest work of conjecture and refutation<ref name= trialAndErr/> — certainty, perhaps, is where difficulties in telling truths from non-truths arise most easily.

Measurements in scientific work are usually accompanied by estimates of their [[uncertainty]].<ref name="conjugatePairs" /> The uncertainty is often estimated by making repeated measurements of the desired quantity. Uncertainties may also be calculated by consideration of the uncertainties of the individual underlying quantities used. Counts of things, such as the number of people in a nation at a particular time, may also have an uncertainty due to [[data collection]] limitations. Or counts may represent a sample of desired quantities, with an uncertainty that depends upon the [[sampling method]] used and the number of samples taken.

In the case of measurement imprecision, there will simply be a 'probable deviation' expressing itself in a study's conclusions. Statistics are different. [[Inductive reasoning#Statistical generalisation|Inductive statistical generalisation]] will take sample data and extrapolate more general conclusions, which has to be justified — and scrutinised. It can even be said that statistical models are only ever useful, [[All models are wrong|but never a complete representation of circumstances]].

In statistical analysis, expected and unexpected bias is a large factor.<ref name="Welsby Weatherall 2022 pp. 793–798">{{cite journal | last1=Welsby | first1=Philip D | last2=Weatherall | first2=Mark | title=Statistics: an introduction to basic principles | journal=Postgraduate Medical Journal | volume=98 | issue=1164 | date=2022-10-01 | issn=0032-5473 | doi=10.1136/postgradmedj-2020-139446 | pages=793–798| pmid=34039698 }}</ref> [[Research question]]s, the collection of data, or the interpretation of results, all are subject to larger amounts of scrutiny than in comfortably logical environments. Statistical models go through a [[Statistical model validation|process for validation]], for which one could even say that awareness of potential biases is more important than the hard logic; errors in logic are easier to find in [[peer review]], after all.{{efn|... and [[John Ioannidis]], in 2005,<ref name="mostRwrong" /> has shown that not everybody respects the principles of statistical analysis; whether they be the principles of inference or otherwise.{{Broader|#Relationship with statistics}}}} More general, claims to rational knowledge, and especially statistics, have to be put into their appropriate context.<ref name="Gauch Jr 2002 p30/ch4">{{harvp|Gauch Jr|2002|loc=Quotes from p. 30, expanded on in ch. 4}}: Gauch gives two simplified statements on what he calls "rational-knowledge claim". It is either "I hold belief X for reasons R with level of confidence C, where inquiry into X is within the domain of competence of method M that accesses the relevant aspects of reality" (inductive reasoning) or "I hold belief X because of presuppositions P." (deductive reasoning)</ref> Simple statements such as '9 out of 10 doctors recommend' are therefore of unknown quality because they do not justify their methodology.

Lack of familiarity with statistical methodologies can result in erroneous conclusions. Foregoing the easy example,{{efn|For instance, extrapolating from a single scientific observation, such as "This experiment yielded these results, so it should apply broadly," exemplifies inductive wishful thinking. [[inductive reasoning#statistical generalization|Statistical generalisation]] is a form of inductive reasoning. Conversely, assuming that a specific outcome will occur based on general trends observed across multiple experiments, as in "Most experiments have shown this pattern, so it will likely occur in this case as well," illustrates faulty [[Deductive reasoning#Probability logic|deductive probability logic]].}} multiple probabilities interacting is where, for example medical professionals,<!--justification: medical professional = authoritative science communicator--><ref name="Gigerenzer 2015">{{cite book | last=Gigerenzer | first=Gerd | title=Risk Savvy | publisher=Penguin | publication-place=New York, New York | date=2015-03-31 | isbn=978-0-14-312710-9 | page=}} leads: (n=1000) only 21% of [[gynaecologist]]s got an example question on [[Bayes' theorem]] right. Book, including the assertion, introduced in {{cite web | last=Kremer | first=William | title=Do doctors understand test results? | website=BBC News | date=6 July 2014 | url=https://www.bbc.com/news/magazine-28166019 | access-date=24 April 2024}}</ref> have shown a lack of proper understanding. [[Bayes' theorem]] is the mathematical principle lining out how standing probabilities are adjusted given new information. The [[boy or girl paradox]] is a common example. In knowledge representation, [[mutual information#Bayesian estimation of mutual information|Bayesian estimation of mutual information]] between [[random variable]]s is a way to measure dependence, independence, or interdependence of the information under scrutiny.<ref name= prml >Christopher M. Bishop [https://www.microsoft.com/en-us/research/uploads/prod/2006/01/Bishop-Pattern-Recognition-and-Machine-Learning-2006.pdf (2006) Pattern Recognition and Machine Learning] pp. 21, 30, 55, 152, 161, 277, 360, 448, 580 </ref> 

Beyond commonly associated [[survey methodology]] of [[field research]], the concept together with [[probabilistic reasoning]] is used to advance fields of science where research objects have no definitive states of being. For example, in [[statistical mechanics]].

==Methods of inquiry==
===Hypothetico-deductive method===

The [[hypothetico-deductive model]], or hypothesis-testing method, or "traditional" scientific method is, as the name implies, based on the formation of [[hypotheses]] and their testing via [[deductive reasoning]]. A hypothesis stating implications, often called [[prediction]]s, that are falsifiable via experiment is of central importance here, as not the hypothesis but its implications are what is tested.{{sfn | Voit | 2019}} Basically, scientists will look at the hypothetical consequences a (potential) [[theory]] holds and prove or disprove those instead of the theory itself. If an [[experiment]]al test of those hypothetical consequences shows them to be false, it follows logically that the part of the theory that implied them was false also. If they show as true however, it does not prove the theory definitively. 

The [[logic]] of this testing is what affords this method of inquiry to be reasoned deductively. The formulated hypothesis is assumed to be 'true', and from that 'true' statement implications are inferred. If the following tests show the implications to be false, it follows that the hypothesis was false also. If test show the implications to be true, new insights will be gained. It is important to be aware that a positive test here will at best strongly imply but not definitively prove the tested hypothesis, as deductive inference (A ⇒ B) is not equivalent like that; only (¬B ⇒ ¬A) is valid logic. Their positive outcomes however, as Hempel put it, provide "at least some support, some corroboration or confirmation for it".<ref name="Hempel 1966">{{cite book | title=Philosophy Of Natural Science | date=1966 | first=Carl Gustav | last=Hempel | author-link=Carl Gustav Hempel | page=7 | url=https://archive.org/stream/1966PhilosophyOfNaturalScienceCarlGHempel1/1966--Philosophy-of-Natural-Science--Carl-G-Hempel%20%281%29_djvu.txt | access-date=30 April 2024}} Hempel illustrates this at [[Ignaz Semmelweis|Semmelweiss]]’ experiments with childbed fever.</ref> This is why [[Frank Popper|Popper]] insisted on fielded hypotheses to be falsifieable, as successful tests imply very little otherwise. As [[Donald A. Gillies|Gillies]] put it, “successful theories are those that survive elimination through falsification”.{{sfn | Voit | 2019}}

Deductive reasoning in this mode of inquiry will sometimes be replaced by [[abductive reasoning]]—the search for the most plausible explanation via logical inference. For example in biology, where general laws are few,{{sfn | Voit | 2019}} as valid deductions rely on solid presuppositions.<ref name="Gauch Jr 2002 p30/ch4"/>

===Inductive method===

The [[inductivism|inductivist approach]] to deriving scientific truth first rose to prominence with [[Francis Bacon]] and particularly with [[Isaac Newton]] and those who followed him.<ref name= novOrganon >[[Francis Bacon]], ''[[Novum Organum]]''</ref> After the establishment of the HD-method, it was often put aside as something of a "fishing expedition" though.{{sfn | Voit | 2019}} It is still valid to some degree, but today's inductive method is often far removed from the historic approach—the scale of the data collected lending new effectiveness to the method. It is most-associated with data-mining projects or large-scale observation projects. In both these cases, it is often not at all clear what the results of proposed experiments will be, and thus knowledge will arise after the collection of data through inductive reasoning.{{efn| name= keplerNewton }}

Where the traditional method of inquiry does both, the inductive approach usually formulates only a [[research question]], not a hypothesis. Following the initial question instead, a suitable "high-throughput method" of data-collection is determined, the resulting data processed and 'cleaned up', and conclusions drawn after. "This shift in focus elevates the data to the supreme role of revealing novel insights by themselves".{{sfn | Voit | 2019}}

The advantage the inductive method has over methods formulating a hypothesis that it is essentially free of "a researcher's preconceived notions" regarding their subject. On the other hand, inductive reasoning is always attached to a measure of certainty, as all inductively reasoned conclusions are.{{sfn | Voit | 2019}} This measure of certainty can reach quite high degrees, though. For example, in the determination of large [[prime number|primes]], which are used in [[encryption software]].{{sfnp|Gauch|2003|p=159}}

===Mathematical modelling===

[[Mathematical modelling]], or allochthonous reasoning, typically is the formulation of a hypothesis followed by building mathematical constructs that can be tested in place of conducting physical laboratory experiments. This approach has two main factors: simplification/abstraction and secondly a set of correspondence rules. The correspondence rules lay out how the constructed model will relate back to reality-how truth is derived; and the simplifying steps taken in the abstraction of the given system are to reduce factors that do not bear relevance and thereby reduce unexpected errors.{{sfn | Voit | 2019}} These steps can also help the researcher in understanding the important factors of the system, how far parsimony can be taken until the system becomes more and more unchangeable and thereby stable. Parsimony and related principles are further explored [[#Confirmation theory|below]].

Once this translation into mathematics is complete, the resulting model, in place of the corresponding system, can be analysed through purely mathematical and computational means. The results of this analysis are of course also purely mathematical in nature and get translated back to the system as it exists in reality via the previously determined correspondence rules—iteration following review and interpretation of the findings. The way such models are reasoned will often be mathematically deductive—but they don't have to be. An example here are [[Monte Carlo method|Monte-Carlo simulations]]. These generate empirical data "arbitrarily", and, while they may not be able to reveal universal principles, they can nevertheless be useful.{{sfn | Voit | 2019}}

==Scientific inquiry==
Scientific inquiry generally aims to obtain [[knowledge]] in the form of [[#suitableTest|testable explanations]]<ref name="SuitableTest">Peirce, Charles S., Carnegie application (L75, 1902), ''New Elements of Mathematics'' v. 4, pp. 37–38: "For it is not sufficient that a hypothesis should be a justifiable one. Any hypothesis that explains the facts is justified critically. But among justifiable hypotheses we have to select that one which is suitable for being tested by experiment."</ref><ref name="econ">Peirce, Charles S. (1902), Carnegie application, see MS L75.329330, from [http://www.cspeirce.com/menu/library/bycsp/l75/ver1/l75v1-08.htm#m27 Draft D] {{Webarchive|url=https://web.archive.org/web/20110524021101/http://www.cspeirce.com/menu/library/bycsp/l75/ver1/l75v1-08.htm#m27|date=2011-05-24}} of Memoir 27: "Consequently, to discover is simply to expedite an event that would occur sooner or later, if we had not troubled ourselves to make the discovery. Consequently, the art of discovery is purely a question of economics. The economics of research is, so far as logic is concerned, the leading doctrine concerning the art of discovery. Consequently, the conduct of abduction, which is chiefly a question of heuretic and is the first question of heuretic, is to be governed by economical considerations."</ref> that scientists can use to [[Predictability|predict]] the results of future experiments. This allows scientists to gain a better understanding of the topic under study, and later to use that understanding to intervene in its causal mechanisms (such as to cure disease). The better an explanation is at making predictions, the more useful it frequently can be, and the more likely it will continue to explain a body of evidence better than its alternatives. The most successful explanations – those that explain and make accurate predictions in a wide range of circumstances – are often called [[scientific theories]].{{efn-ua|name= aQuestion}}

Most experimental results do not produce large changes in human understanding; improvements in theoretical scientific understanding typically result from a gradual process of development over time, sometimes across different domains of science.<ref>Stanovich, Keith E. (2007). ''How to Think Straight About Psychology''. Boston: Pearson Education. p. 123</ref> Scientific models vary in the extent to which they have been experimentally tested and for how long, and in their acceptance in the scientific community. In general, explanations become accepted over time as evidence accumulates on a given topic, and the explanation in question proves more powerful than its alternatives at explaining the evidence. Often subsequent researchers re-formulate the explanations over time, or combined explanations to produce new explanations.

===Properties of scientific inquiry===

Scientific knowledge is closely tied to [[Empirical evidence|empirical findings]] and can remain subject to [[falsifiability|falsification]] if new experimental observations are incompatible with what is found. That is, no theory can ever be considered final since new problematic evidence might be discovered. If such evidence is found, a new theory may be proposed, or (more commonly) it is found that modifications to the previous theory are sufficient to explain the new evidence. The strength of a theory relates to how long it has persisted without major alteration to its core principles.

Theories can also become subsumed by other theories. For example, Newton's laws explained thousands of years of scientific observations of the planets [[#precession of Mercury|almost perfectly]]. However, these laws were then determined to be special cases of a more general theory ([[Theory of relativity|relativity]]), which explained both the (previously unexplained) exceptions to Newton's laws and predicted and explained other observations such as the deflection of [[light]] by [[gravity]]. Thus, in certain cases independent, unconnected, scientific observations can be connected, unified by principles of increasing explanatory power.{{sfnp|Brody|1993 |pp=44–45}}{{sfnp|Goldhaber|Nieto|2010|page=942}}

Since new theories might be more comprehensive than what preceded them, and thus be able to explain more than previous ones, successor theories might be able to meet a higher standard by explaining a larger body of observations than their predecessors.{{sfnp|Brody|1993|pp=44–45}} For example, the theory of [[evolution]] explains the [[Biodiversity|diversity of life on Earth]], how species adapt to their environments, and many other [[pattern]]s observed in the natural world;<ref name="Hall08">{{cite book |editor1-last = Hall |editor1-first = B.K. |editor2-last = Hallgrímsson |editor2-first = B. |title = Strickberger's Evolution |year = 2008 |edition = 4th |publisher = Jones & Bartlett |isbn = 978-0-7637-0066-9 |url = https://archive.org/details/strickbergersevo0000hall/page/762 |page = [https://archive.org/details/strickbergersevo0000hall/page/762 762] }}</ref><ref name="Cracraft05">{{cite book | editor1-last = Cracraft | editor1-first = J. | editor2-last = Donoghue | editor2-first = M.J. | title = Assembling the tree of life | publisher = Oxford University Press | year = 2005 | page = 592 | isbn = 978-0-19-517234-8 | url = https://books.google.com/books?id=6lXTP0YU6_kC&q=Assembling+the+tree+of+life | access-date = 2020-10-20  | archive-date = 2023-11-29  | archive-url = https://web.archive.org/web/20231129112730/https://books.google.com/books?id=6lXTP0YU6_kC&q=Assembling+the+tree+of+life#v=snippet&q=Assembling%20the%20tree%20of%20life&f=false | url-status = live }}</ref> its most recent major modification was unification with [[genetics]] to form the [[Extended evolutionary synthesis|modern evolutionary synthesis]]. In subsequent modifications, it has also subsumed aspects of many other fields such as [[biochemistry]] and [[molecular biology]].

<!--(hidden; reason: completely unsourced (A translation of Aristotle cannot possibly be a source for "The classical model of scientific inquiry derives from Aristotle".)
===Models of scientific inquiry===
{{Main|Models of scientific inquiry}}

The classical model of scientific inquiry [[History of scientific method#Aristotle|derives from Aristotle]],<ref>
{{cite book |author=[[Aristotle]] |chapter=[[Prior Analytics]] |translator=Hugh Tredennick |pages=181–531 |title=Aristotle, Volume&nbsp;1 |series=[[Loeb Classical Library]] |publisher=William Heinemann |place=London |year=1938}}
</ref> who distinguished the forms of approximate and exact reasoning, set out the threefold scheme of [[abductive reasoning|abductive]], [[deductive reasoning|deductive]], and [[inductive reasoning|inductive]] [[inference]], and also treated the compound forms such as reasoning by [[analogy]].

The [[hypothetico-deductive model]] or method is a proposed description of the scientific method. Here, predictions from the hypothesis are central: if one assumes the hypothesis to be true, what consequences follow? If a subsequent empirical investigation does not demonstrate that these consequences or predictions correspond to the observable world, the hypothesis can be concluded to be false.

-->
==Heuristics==

=== Confirmation theory ===

During the course of history, one theory has succeeded another, and some have suggested further work while others have seemed content just to explain the phenomena. The reasons why one theory has replaced another are not always obvious or simple. The philosophy of science includes the question: ''What criteria are satisfied by a 'good' theory''. This question has a long history, and many scientists, as well as philosophers, have considered it. The objective is to be able to choose one theory as preferable to another without introducing [[cognitive bias]].<ref name=Kuhn>
[[Thomas Kuhn]] formally stated this need for the "norms for rational theory choice". One of his discussions is reprinted in {{cite book |title=The Road since Structure: Philosophical Essays, 1970–1993 |author=Thomas S Kuhn |chapter-url=https://books.google.com/books?id=sXufWLnPp94C&pg=PA208 |pages=208 ''ff'' |chapter=Chapter 9: Rationality and Theory Choice  |editor=James Conant, John Haugeland |edition=2nd |publisher=University of Chicago Press |isbn=0226457990 |date=2002-11-01}}
</ref> Though different thinkers emphasize different aspects,{{efn-lg|Differing accounts of which elements constitute a ''good theory'': 
* Kuhn (1977) identified: accuracy; consistency (both internal and with other relevant currently accepted theories); scope (its consequences should extend beyond the data it is required to explain); simplicity (organizing otherwise confused and isolated phenomena); fruitfulness (for further research);<ref>Kuhn, T.S. (1977) Objectivity, Value Judgment, and Theory Choice. In: Kuhn, T.S., Ed., The Essential Tension—Selected Studies in Scientific Tradition and Change, The University of Chicago Press, Chicago, 320-339.</ref>
* Colyvan (2001) listed simplicity/parsimony, unificatory/explanatory power, boldness/fruitfulness, and elegance;<ref name=Colyvan>
{{cite book |title=The Indispensability of Mathematics |author=Mark Colyvan |url=https://books.google.com/books?id=OBs-TSFopLkC&pg=PA78 |pages=78–79 |isbn=0195166612 |year=2001 |publisher=Oxford University Press}}
</ref>
* Weinert (2004) noted the recurring theme of invariance;{{efn-lg|name=invariantTheme|Friedel Weinert in ''The Scientist as Philosopher'' (2004) noted the theme of invariance as a fundamental aspect of a scientific account of reality in many writings from around 1900 onward, such as works by [[Henri Poincaré]] (1902), [[Ernst Cassirer]] (1920), [[Max Born]] (1949 and 1953), [[Paul Dirac]] (1958), [[Olivier Costa de Beauregard]] (1966), [[Eugene Wigner]] (1967), [[Lawrence Sklar]] (1974), [[Michael Friedman (philosopher)|Michael Friedman]] (1983), [[John D. Norton]] (1992), [[Nicholas Maxwell]] (1993), [[Alan Cook (physicist)|Alan Cook]] (1994), [[Alistair Cameron Crombie]] (1994), [[Margaret Morrison (philosopher)|Margaret Morrison]] (1995), [[Richard Feynman]] (1997), [[Robert Nozick]] (2001), and [[Tim Maudlin]] (2002).<ref name="Weinert 2004">{{Cite book |last=Weinert |first=Friedel |title=The Scientist as Philosopher: Philosophical Consequences of Great Scientific Discoveries |date=2004 |publisher=[[Springer-Verlag]] |isbn=3540205802 |location=Berlin; New York |pages=62–74 (72) |chapter=Invariance and reality |doi=10.1007/b138529 |oclc=53434974|url=https://cds.cern.ch/record/828852 }}</ref> — [[David Deutsch|Deutsch]] in a 2009 TED talk proclaimed that "the search for hard-to-vary explanations is the origin of all progress".<ref name="DD_TED">{{Cite AV media | time=15:05min | url=https://www.ted.com/talks/david_deutsch_a_new_way_to_explain_explanation | title=A new way to explain explanation |date=October 2009 | last=Deutsch | first=David | publisher=TED talk | access-date=16 September 2018 | archive-date=4 November 2018 | archive-url=https://web.archive.org/web/20181104012430/https://www.ted.com/talks/david_deutsch_a_new_way_to_explain_explanation |url-status=live }} Also available from [https://www.youtube.com/watch?v=folTvNDL08A YouTube] {{Webarchive|url=https://web.archive.org/web/20221108112725/https://www.youtube.com/watch?v=folTvNDL08A |date=8 November 2022 }}.</ref>}}
* [[Stephen Hawking|Hawking]] (2010): simplicity/parsimony, unificatory/explanatory power, and elegance, but did not mention fruitfulness.<ref name=Hawking>
{{cite book |title=The Grand Design |pages=51–52 |chapter=What is reality? |isbn=978-0553907070 |year=2010 |publisher=Random House Digital, Inc |chapter-url=https://books.google.com/books?id=RoO9jkV-yzIC&pg=PA51 |author1=Stephen Hawking |author2=Leonard Mlodinow }} See also: [[model-dependent realism]].
</ref> 
}} a good theory:

*is accurate ''(the trivial element)'';
*is consistent, both internally and with other relevant currently accepted theories;
*has explanatory power, meaning its consequences extend beyond the data it is required to explain;
*has unificatory power; as in its organizing otherwise confused and isolated phenomena
*and is fruitful for further research.

In trying to look for such theories, scientists will, given a lack of guidance by empirical evidence, try to adhere to:

*parsimony in causal explanations 
*and look for invariant observations.
*Scientists will sometimes also list the very subjective criteria of "formal elegance" which can indicate multiple different things.

The goal here is to make the choice between theories less arbitrary. Nonetheless, these criteria contain subjective elements, and should be considered [[heuristics]] rather than a definitive.{{efn-lg|name=Pars_and_El|...Hawking & Mlodinow on criteria for a good theory: "The above criteria are obviously subjective. Elegance, for example, is not something easily measured, but it is highly prized among scientists." The idea of 'too baroque' is connected to 'simplicity': "a theory jammed with fudge factors is not very elegant. To paraphrase Einstein, a theory should be as simple as possible, but not simpler".<ref name=Hawking/> See also:<ref name=Baker/>}} Also, criteria such as these do not necessarily decide between alternative theories. Quoting [[Alexander Bird|Bird]]:<ref name=Bird>
{{cite encyclopedia |date= Aug 11, 2011 |author=Bird, Alexander |title=§4.1 Methodological Incommensurability |encyclopedia=The Stanford Encyclopedia of Philosophy (Spring 2013 Edition) |editor=Edward N. Zalta |url= http://plato.stanford.edu/entries/thomas-kuhn/#4.1}}
</ref>

{{quote|"[Such criteria] cannot determine scientific choice. First, which features of a theory satisfy these criteria may be disputable (''e.g.'' does simplicity concern the ontological commitments of a theory or its mathematical form?). Secondly, these criteria are imprecise, and so there is room for disagreement about the degree to which they hold. Thirdly, there can be disagreement about how they are to be weighted relative to one another, especially when they conflict."}}

It also is debatable whether existing scientific theories satisfy all these criteria, which may represent goals not yet achieved. For example, explanatory power over all existing observations is satisfied by no one theory at the moment.<ref name=Realism>
See {{cite book |title=The Grand Design |author1=Stephen Hawking |author2=Leonard Mlodinow |url=https://books.google.com/books?id=RoO9jkV-yzIC&pg=PA9 |page=8 |quote=It is a whole family of different theories, each of which is a good description of observations only in some range of physical situations...But just as there is no map that is a good representation of the earth's entire surface, there is no single theory that is a good representation of observations in all situations. |isbn=978-0553907070 |year=2010 |publisher=Random House Digital, Inc}}
</ref><ref name=Davies>
{{cite web |title=Epistemological pluralism |author=E Brian Davies |url=http://philsci-archive.pitt.edu/3083/1/EP3single.doc |work=PhilSci Archive |year=2006 | page=4 | quote=Whatever might be the ultimate goals of some scientists, science, as it is currently practised, depends on multiple overlapping descriptions of the world, each of which has a domain of applicability. In some cases this domain is very large, but in others quite small.}}
</ref>

==== Parsimony ====

The [[wikt:desiderata|desiderata]] of a "good" theory have been debated for centuries, going back perhaps even earlier than [[Occam's razor]],{{efn|Occam's razor, sometimes referred to as "ontological parsimony", is roughly stated as: Given a choice between two theories, the simplest is the best. This suggestion commonly is attributed to William of Ockham in the 14th-century, although it probably predates him.<ref name=Baker/>}} which is often taken as an attribute of a good theory. Science tries to be simple. When gathered data supports multiple explanations, the most simple explanation for phenomena or the most simple formation of a theory is recommended by the principle of parsimony.{{sfnp|Gauch|2003|p=269}} Scientists go as far as to call simple proofs of complex statements ''beautiful''.

{{Quote| quote=We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.|source=Isaac Newton, ''Philosophiæ Naturalis Principia Mathematica (1723 [3rd ed.])''<ref name="principia" />}}

The concept of parsimony should not be held to imply complete frugality in the pursuit of scientific truth. The general process starts at the opposite end of there being a vast number of potential explanations and general disorder. An example can be seen in [[Paul Krugman]]'s process, who makes explicit to "dare to be silly". He writes that in his work on new theories of international trade he [[literature review|reviewed prior work]] with an open frame of mind and broadened his initial viewpoint even in unlikely directions. Once he had a sufficient body of ideas, he would try to simplify and thus find what worked among what did not. Specific to Krugman here was to "question the question". He recognised that prior work had applied erroneous models to already present evidence, commenting that "intelligent commentary was ignored".{{refn | name=Krugman|{{cite journal | last=Krugman | first=Paul | title=How I Work | journal=The American Economist | publisher=Sage Publications, Inc. | volume=37 | issue=2 | year=1993 | issn=0569-4345 | jstor=25603965 | pages=25–31 | doi=10.1177/056943459303700204 }} ...I have already implicitly given my four basic rules for research. Let me now state them explicitly, then explain. Here are the rules: 
# Listen to the Gentiles
# Question the question
# Dare to be silly
# Simplify, simplify
<!--credit to q:Science-->}} Thus touching on the need to bridge the common bias against other circles of thought.{{sfnp | Fleck | 1979 | p=27}}

==== Elegance ====

Occam's razor might fall under the heading of "simple elegance", but it is arguable that ''parsimony'' and ''elegance'' pull in different directions. Introducing additional elements could simplify theory formulation, whereas simplifying a theory's ontology might lead to increased syntactical complexity.<ref name=Baker>
{{cite encyclopedia |author=Baker, Alan |title=Simplicity |encyclopedia=The Stanford Encyclopedia of Philosophy (Summer 2011 Edition) |editor=Edward N. Zalta |url=http://plato.stanford.edu/archives/sum2011/entries/simplicity/ |date=Feb 25, 2010}}
</ref> 

Sometimes ad-hoc modifications of a failing idea may also be dismissed as lacking "formal elegance". This appeal to what may be called "aesthetic" is hard to characterise, but essentially about a sort of familiarity. Though, argument based on "elegance" is contentious and over-reliance on familiarity will breed stagnation.<ref name=Colyvan/>

==== Invariance ====

Principles of invariance have been a theme in scientific writing, and especially physics, since at least the early 20th century.{{efn-lg|name=invariantTheme}} The basic idea here is that good structures to look for are those independent of perspective, an idea that has featured earlier of course for example in [[Mill's Methods]] of difference and agreement—methods that would be referred back to in the context of contrast and invariance.<ref name="O&H 1995">{{cite journal | last1=van Overwalle | first1=Frank J. | last2=Heylighen | first2=Francis P. | title=Relating covariation information to causal dimensions through principles of contrast and invariance | journal=European Journal of Social Psychology | volume=25 | issue=4 | date=1995 | issn=0046-2772 | doi=10.1002/ejsp.2420250407 | pages=435–455 | url=http://pcp.vub.ac.be/Papers/Contrast&Invariance.html}}</ref> But as tends to be the case, there is a difference between something being a basic consideration and something being given weight. Principles of invariance have only been given weight in the wake of Einstein's theories of relativity, which reduced everything to relations and were thereby fundamentally unchangeable, unable to be varied.<ref name="Wigner1967"/>{{efn |name=WeinertEddingtonEinstein}} As [[David Deutsch]] put it in 2009: "the search for hard-to-vary explanations is the origin of all progress".<ref name="DD_TED">{{Cite AV media | time=15:05min | url=https://www.ted.com/talks/david_deutsch_a_new_way_to_explain_explanation | title=A new way to explain explanation |date=October 2009 | last=Deutsch | first=David | publisher=TED talk | access-date=16 September 2018 | archive-date=4 November 2018 | archive-url=https://web.archive.org/web/20181104012430/https://www.ted.com/talks/david_deutsch_a_new_way_to_explain_explanation |url-status=live }} Also available from [https://www.youtube.com/watch?v=folTvNDL08A YouTube] {{Webarchive|url=https://web.archive.org/web/20221108112725/https://www.youtube.com/watch?v=folTvNDL08A |date=8 November 2022 }}.</ref>

An example here can be found in one of [[Einstein's thought experiments#Falling painters and accelerating elevators|Einstein's thought experiments]]. The one of a lab suspended in empty space is an example of a useful invariant observation. He imagined the absence of gravity and an experimenter free floating in the lab. — If now an entity pulls the lab upwards, accelerating uniformly, the experimenter would perceive the resulting force as gravity. The entity however would feel the work needed to accelerate the lab continuously.{{efn| name=WeinertEddingtonEinstein |[[Arthur Eddington]], 1920: "The relativity theory of physics reduces everything to relations; that is to say, it is structure, not material, which counts." — Weinert, giving the Einstein example and quoting: "Eddington, Space, Time and Gravitation (1920), 197"<ref name="Weinert 2004"/>}} Through this experiment Einstein was able to equate gravitational and inertial mass; something unexplained by Newton's laws, and an early but "powerful argument for a generalised postulate of relativity".<ref name="Einstein1916">{{cite book|last1=Einstein|first1=Albert|title=Relativity: The Special and the General Theory|date=1961|publisher=Crown Publishers, Inc.|location=New York|isbn=978-0-517-88441-6|edition=15th|pages=75–79}}</ref>

{{Quote|quote=The feature, which suggests reality, is always some kind of invariance of a structure independent of the aspect, the projection.|source=[[Max Born]], ‘Physical Reality’ (1953), 149 — as quoted by Weinert (2004)<ref name="Weinert 2004"/>}}

The discussion on [[invariance (physics)|invariance]] in physics is often had in the more specific context of [[symmetry (physics)|symmetry]].<ref name="Wigner1967">{{cite book | last=Wigner | first=Eugene Paul | date=1967 | title=Symmetries and reflections | publisher=Indiana University Press | page=15}} : Wigner also differentiates between geometrical invariance principles, and the "new" ones that arose in the wake of Einstein's theories of relativity that he calls dynamic invariance principles.</ref> The Einstein example above, in the parlance of Mill would be an agreement between two values. In the context of invariance, it is a variable that remains unchanged through some kind of transformation or change in perspective. And discussion focused on symmetry would view the two perspectives as systems that share a relevant aspect and are therefore symmetrical. 

Related principles here are [[falsifiability]] and [[testability]]. The opposite of something being ''hard-to-vary'' are theories that resist falsification—a frustration that was expressed colourfully by [[Wolfgang Pauli]] as them being "[[not even wrong]]". The importance of scientific theories to be falsifiable finds especial emphasis in the philosophy of Karl Popper. The broader view here is testability, since it includes the former and allows for additional practical considerations. <ref>{{cite book |last=Keuth |first=Herbert |author-link=:de:Herbert Keuth |chapter=From falsifiability to testability |title=The philosophy of Karl Popper |date=2004 |orig-year=Published in German 2000 |edition=1st English |location=Cambridge, UK; New York |publisher=[[Cambridge University Press]] |pages=[https://books.google.com/books?id=wxzoBfQYhYAC&pg=PA48 48–49] |chapter-url=https://books.google.com/books?id=wxzoBfQYhYAC&pg=PA48 |isbn=9780521548304 |oclc=54503549 |quote=Consequently, the ''universal statements'', which are contradicted by the basic statements, ''are not strictly refutable''. Like singular statements and probability statements, they are empirically testable, but their tests do not have certain, definite results, do not result in strict verification or falsification but only in temporary acceptance or rejection.}}</ref><ref name="l921">{{cite book | last=Krantz | first=S.G. | title=Mathematical Apocrypha Redux: More Stories and Anecdotes of Mathematicians and the Mathematical | publisher=Mathematical Association of America | series=MAA spectrum | year=2005 | isbn=978-0-88385-554-6 | url=https://books.google.com/books?id=8mBdvAjk_gQC | access-date=29 August 2024 | page=194}}</ref>

==Philosophy and discourse==<!--Section set to frame 'usefulness' in order to encourage perspectives that advance discussion; not (just) critique without context. Keep in mind, that 'useful' needs to be the consideration of your source, and not any interpretation of it.-->
{{See also|Philosophy of science|Sociology of scientific knowledge}}
{{anchor|Characterization}}
Philosophy of science looks at [[#polyaFirstUnderstand|the underpinning logic]] of the scientific method, at what separates [[Demarcation problem|science from non-science]], and the [[Research ethics|ethic]] that is implicit in science. There are basic assumptions, derived from philosophy by at least one prominent scientist,{{efn-ua|name= introspection| [https://en.wikisource.org/wiki/Page%3APopular_Science_Monthly_Volume_12.djvu/300 Never fail to recognize an idea]... .— C. S. Peirce, ILLUSTRATIONS OF THE LOGIC OF SCIENCE, SECOND PAPER. —HOW TO MAKE OUR IDEAS CLEAR. ''Popular Science Monthly'' '''Volume 12''', January 1878, p.286<ref name= How/>}}<ref name=comprehensibility/> that form the base of the scientific method – namely, that reality is objective and consistent, that humans have the capacity to perceive reality accurately, and that rational explanations exist for elements of the real world.<ref name=comprehensibility>Einstein, Albert (1936, 1956) One may say "the eternal mystery of the world is its comprehensibility." From the article "Physics and Reality" (1936), reprinted in ''Out of My Later Years'' (1956). 'It is one of the great realizations of Immanuel Kant that the setting up of a real external world would be senseless without this comprehensibility.'</ref> These assumptions from [[naturalism (philosophy)|methodological naturalism]] form a basis on which science may be grounded. [[Logical positivism|Logical positivist]], [[empiricism|empiricist]], [[falsifiability|falsificationist]], and other theories have criticized these assumptions and given alternative accounts of the logic of science, but each has also itself been criticized.

There are several kinds of modern philosophical conceptualizations and attempts at definitions of the method of science.{{efn-lg|There is no universally agreed upon definition of the method of science. This was expressed with [[Neurath's boat]] already in 1913. There is however a consensus that stating this somewhat nihilistic assertion without introduction and in too unexpected a fashion is counterproductive, confusing, and can even be damaging. There may never be one, too. As [[Steven Weinberg|Weinberg]] described it in 1995:<ref name="Weinberg 1995">Weinberg, (1995) “The Methods of Science … And Those By Which We Live”, page: 8</ref> {{Quote|quote=The fact that the standards of scientific success shift with time does not only make the philosophy of science difficult; it also raises problems for the public understanding of science. We do not have a fixed scientific method to rally around and defend.}}}} The one attempted by the ''unificationists'', who argue for the existence of a unified definition that is useful (or at least 'works' in every context of science). The ''pluralists'', arguing degrees of science being too fractured for a universal definition of its method to by useful. And those, who argue that the very attempt at definition is already detrimental to the free flow of ideas. 

Additionally, there have been views on the social framework in which science is done, and the impact of the sciences social envrionment on research. Also, there is 'scientific method' as popularised by Dewey in ''How We Think'' (1910) and Karl Pearson in ''Grammar of Science'' (1892), as used in fairly uncritical manner in education.

=== Pluralism ===
{{Main|Scientific pluralism}}

Scientific pluralism is a position within the [[philosophy of science]] that rejects various proposed [[unity of science|unities]] of scientific method and subject matter. Scientific pluralists hold that science is not unified in one or more of the following ways: the [[metaphysics]] of its subject matter, the [[epistemology]] of scientific knowledge, or the [[research methods]] and models that should be used. Some pluralists believe that pluralism is necessary due to the nature of science. Others say that since [[scientific discipline]]s already vary in practice, there is no reason to believe this variation is wrong until a specific unification is [[empirically]] proven. Finally, some hold that pluralism should be allowed for [[normative]] reasons, even if unity were possible in theory.

=== Unificationism ===
{{Main|Unity of science}}

Unificationism, in science, was a central tenet of [[logical positivism]].<ref name="Neurath† Bonk 2011">{{cite book | last1=Neurath† | first1=Otto | author1-link=Otto Neurath| last2=Bonk | first2=Thomas | title=Otto Neurath and the Unity of Science | chapter=Unity of Science and Logical Empiricism: A Reply | publisher=Springer Netherlands | publication-place=Dordrecht | date=2011 | isbn=978-94-007-0142-7 | doi=10.1007/978-94-007-0143-4_2 | pages=15–30}}</ref><ref name="McGill 1937">{{cite journal | last=McGill | first=V. J. | title=Logical Positivism and the Unity of Science | journal=Science & Society | publisher=Guilford Press | volume=1 | issue=4 | year=1937 | issn=0036-8237 | jstor=40399117 | pages=550–561 }}</ref> Different logical positivists construed this doctrine in several different ways, e.g. as a [[reductionism|reductionist]] thesis, that the objects investigated by the [[special sciences]] reduce to the objects of a common, putatively more basic domain of science, usually thought to be physics; as the thesis that all theories and results of the various sciences can or ought to be expressed in a common language or "universal slang"; or as the thesis that all the special sciences share a common scientific method.{{efn|name=unifiedMethod|1= The topics of study, as expressed in the vocabulary of its scientists, are approached by a "single unified method".<ref name= cowles />{{rp|pp.8,13,33–35,60}} A topic is [[Unification of theories in physics|unified]] by its [[Predicate variable|predicate]]s, which describe a [[system]] of mathematical [[Expression (mathematics)|expression]]s.<ref name=Knight1989 >Kevin Knight (1989) [https://kevincrawfordknight.github.io/papers/unification-knight.pdf Unification: A Multidisciplinary Survey] ACM Computing Surveys, Vol. 21, No. 1, March 1989 </ref>{{rp|93-94,113-117}} The values which a [[Predicate (mathematical logic)|predicate]] might take, then serve as [[Witness (mathematics)|witness]] to the validity of a predicated expression (that is, ''true'' or ''false''; 'predicted but not yet observed'; 'corroborates', etc.).}}

Development of the idea has been troubled by accelerated advancement in technology that has opened up many new ways to look at the world.

{{Quote|quote=The fact that the standards of scientific success shift with time does not only make the philosophy of science difficult; it also raises problems for the public understanding of science. We do not have a fixed scientific method to rally around and defend. 
|source=[[Steven Weinberg]], 1995<ref name="Weinberg 1995" />}}

=== Epistemological anarchism ===
{{Main|Epistemological anarchism}}

{{anchor|noMethod}}[[Paul Feyerabend]] examined the history of science, and was led to deny that science is genuinely a methodological process. In his book ''[[Against Method]]'' he argued that no description of scientific method [[#critiquesOfFeyerabend|could possibly be broad enough]] to include all the approaches and methods used by scientists, and that there are no useful and exception-free [[methodology|methodological rules]] governing the progress of science. In essence, he said that for any specific method or norm of science, one can find a historic episode where violating it has contributed to the progress of science. He jokingly suggested that, if believers in the scientific method wish to express a single universally valid rule, it should be '[[#theTermSci|anything goes]]'.<ref>[[Paul Feyerabend|Feyerabend, Paul K.]], ''Against Method, Outline of an Anarchistic Theory of Knowledge'', 1st published, 1975. Reprinted, Verso, London, 1978.
</ref> As has been argued before him however, this is uneconomic; [[Problem solving|problem solver]]s, and researchers are to be prudent with their resources during their inquiry.{{efn-ua|name= FRL-1.136 |{{harvp|Peirce|1899}} First rule of logic (F.R.L)<ref name= reasonsFirstRule /> Paragraph 1.136: From the first rule of logic, if we truly desire the goal of the inquiry we are not to waste our resources.<ref name=econ/><ref name= SuitableTest/> — [[Terence Tao]] wrote on the matter that not all approaches can be regarded as "equally suitable and deserving of equal resources" because such positions would "sap mathematics of its sense of direction and purpose".<ref name= taoTime >{{cite arXiv | last=Tao | first=Terence | title=What is good mathematics? | date=13 February 2007 | eprint=math/0702396 }}</ref>}} 

A more general inference against formalised method has been found through research involving interviews with scientists regarding their conception of method. This research indicated that scientists frequently encounter difficulty in determining whether the available evidence supports their hypotheses. This reveals that there are no straightforward mappings between overarching methodological concepts and precise strategies to direct the conduct of research.<ref name="Schickore Hangel 2019">{{cite journal | last1=Schickore | first1=Jutta | last2=Hangel | first2=Nora | title="It might be this, it should be that…" uncertainty and doubt in day-to-day research practice | journal=European Journal for Philosophy of Science | volume=9 | issue=2 | date=2019 | issn=1879-4912 | doi=10.1007/s13194-019-0253-9 | page=}}</ref>

=== Education ===
{{See also|Philosophy of education|Scientific literacy}}

In [[science education]], the idea of a general and universal scientific method has been notably influential, and numerous studies (in the US) have shown that this framing of method often forms part of both students’ and teachers’ conception of science.<ref name="Aikenhead 1987 pp. 459–487">{{cite journal | last=Aikenhead | first=Glen S. | title=High-school graduates' beliefs about science-technology-society. III. Characteristics and limitations of scientific knowledge | journal=Science Education | volume=71 | issue=4 | date=1987 | issn=0036-8326 | doi=10.1002/sce.3730710402 | pages=459–487| bibcode=1987SciEd..71..459A }}</ref><ref name="Osborne Simon Collins 2003 pp. 1049–1079">{{cite journal | last1=Osborne | first1=Jonathan | last2=Simon | first2=Shirley | last3=Collins | first3=Sue | title=Attitudes towards science: A review of the literature and its implications | journal=International Journal of Science Education | volume=25 | issue=9 | date=2003 | issn=0950-0693 | doi=10.1080/0950069032000032199 | pages=1049–1079| bibcode=2003IJSEd..25.1049O }}</ref> This convention of traditional education has been argued against by scientists, as there is a consensus that educations' sequential elements and unified view of scientific method do not reflect how scientists actually work.<ref name="Bauer 1992 p.">{{cite book | last=Bauer | first=Henry H. | title=Scientific Literacy and the Myth of the Scientific Method | publisher=University of Illinois Press | date=1992 | isbn=978-0-252-06436-4 | page=}}</ref><ref name="McComas 1996 pp. 10–16">{{cite journal | last=McComas | first=William F. | title=Ten Myths of Science: Reexamining What We Think We Know About the Nature of Science | journal=School Science and Mathematics | volume=96 | issue=1 | date=1996 | issn=0036-6803 | doi=10.1111/j.1949-8594.1996.tb10205.x | pages=10–16}}</ref><ref name="Wivagg 2002 pp. 645–646">{{cite journal | last=Wivagg | first=Dan | title=The Dogma of "The" Scientific Method | journal=The American Biology Teacher | volume=64 | issue=9 | date=2002-11-01 | issn=0002-7685 | doi=10.2307/4451400 | pages=645–646| jstor=4451400 }}</ref> 

How the sciences make knowledge has been taught in the context of "the" scientific method (singular) since the early 20th century. Various systems of education, including but not limited to the US, have taught the method of science as a process or procedure, structured as a definitive series of steps:{{refn | Traditionally 5, after Dewey's 1910 idea of a "complete act of thought". He held that thought-process best represented science (for education).<ref name="Rudolph2005">{{cite journal | last=Rudolph | first=John L. | title=Epistemology for the Masses: The Origins of "The Scientific Method" in American Schools | journal=History of Education Quarterly | publisher=[History of Education Society, Wiley] | volume=45 | issue=3 | year=2005 | issn=0018-2680 | jstor=20461985 | pages=341–376, quote on 366 | doi=10.1111/j.1748-5959.2005.tb00039.x | quote=In chapter six, Dewey analyzed what he called a "complete act of thought." Any such act, he wrote, consisted of the following five "logically distinct" steps: "(i) a felt difficulty; (ii) its location and definition; (iii) suggestion of possible solution; (iv) development by reasoning of the bearings of the suggestion; [and] (v) further observation and experiment leading to its acceptance or rejection."}}</ref> These steps would end up being simplified and adjusted, often shortened to 4,<ref name="SpieceColosi2000"/> or extended to include various practices.<ref name="SchusterPowers2005"/>}} observation, hypothesis, prediction, experiment.

This version of the method of science has been a long-established standard in primary and secondary education, as well as the biomedical sciences.{{refn | Specifically, the scientific method has featured in introductory science courses for biology,<ref name="SpieceColosi2000">{{cite journal | last1=Spiece | first1=Kelly R. | last2=Colosi | first2=Joseph | title=Redefining the "Scientific Method" | journal=The American Biology Teacher | volume=62 | issue=1 | date=1 January 2000 | issn=0002-7685 | jstor=4450823 | doi=10.2307/4450823 | pages=32–40}}</ref> medicine,<ref name="SchusterPowers2005">{{cite book | last1=Schuster | first1=D.P. | last2=Powers | first2=W.J. | title=Translational and Experimental Clinical Research | publisher=Lippincott Williams & Wilkins | year=2005 | isbn=978-0-7817-5565-8 | url=https://books.google.com/books?id=C7pZftbI0ZMC&pg=PA3 | access-date=20 May 2024 | page=4}} Schuster & Powers hold that sources for research questions are: attempts to explain the cause of novel observations, verifying the predictions of existing theory, literature sources, and technology.</ref> and psychology.<ref name="StangorWalinga2014">{{cite book | last1=Stangor | first1=Charles | last2=Walinga | first2=Jennifer | author3=BC Open Textbook Project | author4=BCcampus | title=Introduction to psychology | publisher=BCcampus, BC Open Textbook Project | publication-place=[Victoria] | year=2014 | isbn=978-1-77420-005-6 | oclc=1014457300 | url=https://opentextbc.ca/introductiontopsychology/chapter/2-1-psychologists-use-the-scientific-method-to-guide-their-research/}}</ref> Also, in education in general.}} It has long been held to be an inaccurate idealisation of how some scientific inquiries are structured.<ref name="Rudolph2005"/>

The taught presentation of science had to defend demerits such as:<ref name="Emden2021">{{cite journal | last=Emden | first=Markus | title=Reintroducing "the" Scientific Method to Introduce Scientific Inquiry in Schools?: A Cautioning Plea Not to Throw Out the Baby with the Bathwater | journal=Science & Education | volume=30 | issue=5 | date=2021 | issn=0926-7220 | doi=10.1007/s11191-021-00235-w | pages=1037–1039| doi-access=free }}</ref>

* it pays no regard to the social context of science,
* it suggests a singular methodology of deriving knowledge,
* it overemphasises experimentation,
* it oversimplifies science, giving the impression that following a scientific process automatically leads to knowledge,
* it gives the illusion of determination; that questions necessarily lead to some kind of answers and answers are preceded by (specific) questions,
* and, it holds that scientific theories arise from observed phenomena only.<ref name="BrownKumar2013">{{cite journal | last1=Brown | first1=Ronald A. | last2=Kumar | first2=Alok | title=The Scientific Method: Reality or Myth? | journal=Journal of College Science Teaching | publisher=National Science Teachers Association | volume=42 | issue=4 | year=2013 | issn=0047-231X | jstor=43631913 | pages=10–11}}</ref>

The scientific method no longer features in the standards for US education of 2013 ([[Next Generation Science Standards|NGSS]]) that replaced those of 1996 ([[National Science Education Standards|NRC]]). They, too, influenced international science education,<ref name="Emden2021"/> and the standards measured for have shifted since from the singular hypothesis-testing method to a broader conception of scientific methods.<ref name="IoannidouErduran2021">{{cite journal | last1=Ioannidou | first1=Olga | last2=Erduran | first2=Sibel | title=Beyond Hypothesis Testing: Investigating the Diversity of Scientific Methods in Science Teachers' Understanding | journal=Science & Education | volume=30 | issue=2 | date=2021 | issn=0926-7220 | pmid=34720429 | pmc=8550242 | doi=10.1007/s11191-020-00185-9 | pages=345–364}}</ref> These scientific methods, which are rooted in scientific practices and not epistemology, are described as the 3 ''dimensions'' of scientific and engineering practices, crosscutting concepts (interdisciplinary ideas), and disciplinary core ideas.<ref name="Emden2021"/>

The scientific method, as a result of simplified and universal explanations, is often held to have reached a kind of mythological status; as a tool for communication or, at best, an idealisation.<ref name="Thurs2015"/><ref name="McComas 1996 pp. 10–16"/> Education's approach was heavily influenced by John Dewey's, ''[[How We Think]] (1910)''.<ref name= cowles>{{harvp|Cowles|2020|p=264}}</ref> Van der Ploeg (2016) indicated that Dewey's views on education had long been used to further an idea of citizen education removed from "sound education", claiming that references to Dewey in such arguments were undue interpretations (of Dewey).<ref name="van der Ploeg 2016 pp. 145–159">{{cite journal | last=van der Ploeg | first=Piet | title=Dewey versus 'Dewey' on democracy and education | journal=Education, Citizenship and Social Justice | publisher=SAGE Publications | volume=11 | issue=2 | date=8 June 2016 | issn=1746-1979 | doi=10.1177/1746197916648283 | pages=145–159| url=https://pure.rug.nl/ws/files/44567891/1746197916648283.pdf }}</ref>

===Sociology of knowledge===
{{Main|Sociology of scientific knowledge}}

The sociology of knowledge is a concept in the discussion around scientific method, claiming the underlying method of science to be sociological. King explains that sociology distinguishes here between the system of ideas that govern the sciences through an inner logic, and the social system in which those ideas arise.{{efn-lg|"The sociology of knowledge is concerned with "the relationship between human thought and the social context in which it arises."<ref>Here, King quotes [[Peter L. Berger]] and [[Thomas Luckmann|Thomas Luckman]], ''[[The Social Construction of Reality]]'' (London, 1967), 16.</ref> So, on this reading, the sociology of science may be taken to be considered with the analysis of the social context of scientific thought. But scientific thought, most sociologists concede, is distinguished from other modes of thought precisely by virtue of its immunity from social determination — insofar as it is governed by reason rather than by tradition, and insofar as it is rational it escapes determination by "non-logical" social forces." — M. D. King leading into his article on ''Reason, tradition, and the progressiveness of science (1971)''<ref name="King_JA1971">{{cite journal | last=King | first=M. D. | title=Reason, Tradition, and the Progressiveness of Science | journal=History and Theory | publisher=[Wesleyan University, Wiley] | volume=10 | issue=1 | year=1971 | issn=1468-2303 | jstor=2504396 | doi=10.2307/2504396 | pages=3–32}}</ref>}}{{efn-lr|name=Tanqih |1= {{harvp|Sabra|2007}} recounts how [[Kamāl al-Dīn al-Fārisī]] came by his manuscript copy of [[Alhacen]]'s ''[[Book of Optics]]'', which by then was some two centuries old: al-Fārisī's project was to write an advanced optics treatise, but he could not understand optical [[refraction]] using his best resources. His mentor, [[Qutb al-Din al-Shirazi]] recalled having seen Alhacen's manuscript as a youth, and arranged to get al-Fārisī a copy "from a distant country". al-Fārisī is now remembered for his Commentary on Alhacen's ''Book of Optics'' in which he found a satisfactory explanation for the phenomenon of the [[rainbow]]: light rays from the sun are doubly refracted within the raindrops in the air, back to the observer.<ref>{{cite web
 | author1=O'Connor, J. J. |author2=Robertson, E. F. | date=November 1999
 | url=http://www-gap.dcs.st-and.ac.uk/~history/Biographies/Al-Farisi.html
 | title=Kamal al-Din Abu'l Hasan Muhammad Al-Farisi
 | publisher=University of St. Andrews | access-date=2007-06-07 }}</ref> Refraction of the colors from the sun's light then forms the spread of colors in the rainbow.}}

====Thought collectives====

A perhaps accessible lead into what is claimed is [[Ludwik Fleck|Fleck's]] thought, echoed in [[Thomas Kuhn|Kuhn's]] concept of [[normal science]]. According to Fleck, scientists' work is based on a thought-style, that cannot be rationally reconstructed. It gets instilled through the experience of learning, and science is then advanced based on a tradition of shared assumptions held by what he called [[Thought collective|''thought collectives'']]. Fleck also claims this phenomenon to be largely invisible to members of the group.<ref name="Fleck_comp_w/Kuhn">{{cite journal|last=Harwood | first=Jonathan | title=Ludwik Fleck and the Sociology of Knowledge | journal=Social Studies of Science | volume=16 | number=1 | date=1986 | pages=173–187 | doi=10.1177/030631286016001009 | jstor=285293}}</ref>

Comparably, following the [[field research]] in an academic scientific laboratory by [[Bruno Latour|Latour]] and [[Steve Woolgar|Woolgar]], [[Karin Knorr Cetina]] has conducted a comparative study of two scientific fields (namely [[Particle physics|high energy physics]] and [[molecular biology]]) to conclude that the epistemic practices and reasonings within both scientific communities are different enough to introduce the concept of "[[epistemic cultures]]", in contradiction with the idea that a so-called "scientific method" is unique and a unifying concept.<ref>{{Cite book|title=Epistemic cultures: how the sciences make knowledge|last=Knorr-Cetina |first=K. |date=1999|publisher=Harvard University Press |isbn=978-0-674-25893-8|location=Cambridge, Mass.|oclc=39539508}}</ref>{{efn|Comparing 'epistemic cultures' with Fleck 1935, [[Thought collective]]s, (''denkkollektiven''): ''Entstehung und Entwicklung einer wissenschaftlichen Tatsache: Einfǖhrung in die Lehre vom Denkstil und Denkkollektiv''<ref>As cited in {{harvp|Fleck|1979|p=27}}, {{harvp|Fleck|1979|pp=38–50}}</ref> {{harvp|Fleck|1979|p=xxvii}} recognizes that [[#genesisOfScientificFact|facts have lifetimes]], flourishing only after incubation periods. His selected question for investigation (1934) was "[[Thought collective#predicateIsNotStatement|HOW, THEN, DID THIS EMPIRICAL FACT ORIGINATE]] AND IN WHAT DOES IT CONSIST?".<ref>{{harvp|Fleck|1979|p=xxviii}}</ref> But by [[#genesisOfScientificFact|Fleck 1979, p.27]], the thought collectives within the respective fields will have to settle on common specialized terminology, publish their results and further intercommunicate with their colleagues using the common terminology, in order to progress.<ref>{{harvp|Fleck | 1979|p=27}}</ref>
{{see also|Cognitive revolution|Perceptual control theory#The methodology of modeling, and PCT as model}}}}

====Situated cognition and relativism====
{{See also|Postpositivism|Relativism}}

On the idea of Fleck's ''thought collectives'' sociologists built the concept of [[situated cognition]]: that the perspective of the researcher fundamentally affects their work; and, too, more radical views.

[[Norwood Russell Hanson]], alongside [[Thomas Kuhn]] and [[Paul Feyerabend]], extensively explored the theory-laden nature of observation in science. Hanson introduced the concept in 1958, emphasizing that observation is influenced by the [[Situated cognition|observer's conceptual framework]]. He used the concept of [[gestalt psychology|gestalt]] to show how preconceptions can affect both observation and description, and illustrated this with examples like the initial rejection of [[Golgi apparatus|Golgi bodies]] as an artefact of staining technique, and the differing interpretations of the same sunrise by Tycho Brahe and Johannes Kepler. [[Intersubjectivity]] led to different conclusions.<ref name="Hanson1958">{{Citation
|last=Hanson
|first=Norwood
|title=Patterns of Discovery
|year=1958
|publisher=Cambridge University Press
|isbn=978-0-521-05197-2
}}</ref>{{efn|name= Kepler1604 }}

Kuhn and Feyerabend acknowledged Hanson's pioneering work,<ref>{{cite book |last=Kuhn |first=Thomas S. |title=The Structure of Scientific Revolutions |publisher=University of Chicago Press |location=Chicago, IL |year=2009 |isbn=978-1-4432-5544-8 |page=113 |title-link=The Structure of Scientific Revolutions}}<!--ISBN matches 2009 publication, not the 1962.-->
</ref><ref>Feyerabend, Paul K (1960) "Patterns of Discovery" The Philosophical Review (1960) vol. 69 (2) pp. 247–252</ref> although Feyerabend's views on methodological pluralism were more radical. Criticisms like those from Kuhn and Feyerabend prompted discussions leading to the development of the [[strong programme]], a sociological approach that seeks to explain scientific knowledge without recourse to the truth or validity of scientific theories. It examines how scientific beliefs are shaped by social factors such as power, ideology, and interests.

The [[postmodernism|postmodernist]] critiques of science have themselves been the subject of intense controversy. This ongoing debate, known as the [[science wars]], is the result of conflicting values and assumptions between [[postmodernist]] and [[scientific realism|realist]] perspectives. Postmodernists argue that scientific knowledge is merely a discourse, devoid of any claim to fundamental truth. In contrast, realists within the scientific community maintain that science uncovers real and fundamental truths about reality. Many books have been written by scientists which take on this problem and challenge the assertions of the postmodernists while defending science as a legitimate way of deriving truth.<ref>For example:
* ''Higher Superstition: The Academic Left and Its Quarrels with Science'', The Johns Hopkins University Press, 1997
* ''Fashionable Nonsense: Postmodern Intellectuals' Abuse of Science'', Picador. 1999
* ''The Sokal Hoax: The Sham That Shook the Academy'', University of Nebraska Press, 2000 {{ISBN|0-8032-7995-7}}
* ''A House Built on Sand: Exposing Postmodernist Myths About Science'', Oxford University Press, 2000
* ''Intellectual Impostures'', Economist Books, 2003</ref>

==Limits of method==

===Role of chance in discovery===
{{Main|Role of chance in scientific discoveries}}
[[File:Sample of penicillin mould presented by Alexander Fleming to Douglas Macleod, 1935 (9672239344).jpg|thumb|left<!--#lefty anarchy-->|A famous example of discovery being stumbled upon was Alexander Fleming's [[Alexander Fleming#Discovery of penicillin|discovery of penicillin]]. One of his bacteria cultures got contaminated with mould in which surroundings the bacteria had died off; thereby the method of discovery was simply knowing what to look out for.<ref name="Tan & Tatsumura 2015">{{cite journal |last1=Tan |first1=Sy |last2=Tatsumura |first2=Y |date=July 2015 |title=Alexander Fleming (1881–1955): Discoverer of penicillin |journal=Singapore Medical Journal |volume=56 |issue=7 |pages=366–367 |doi=10.11622/smedj.2015105 |pmc=4520913 |pmid=26243971 |quote=An uncovered Petri dish sitting next to an open window became contaminated with mould spores. Fleming observed that the bacteria in proximity to the mould colonies were dying, as evidenced by the dissolving and clearing of the surrounding agar gel. He was able to isolate the mould and identified it as a member of the Penicillium genus.}}</ref>]]

Somewhere between 33% and 50% of all [[Scientific discovery|scientific discoveries]] are estimated to have been ''stumbled upon'', rather than sought out. This may explain why scientists so often express that they were lucky.<ref name=DunbarLuck>Dunbar, K., & Fugelsang, J. (2005). Causal Thinking in Science: How Scientists and Students Interpret the Unexpected. In M. E. Gorman, R.D. Tweney, D. Gooding & A. Kincannon (eds.), ''Scientific and Technical Thinking''. Mahwah, NJ: Lawrence Erlbaum Associates. pp. 57–79.</ref> [[Louis Pasteur]] is credited with the famous saying that "Luck favours the prepared mind", but some psychologists have begun to study what it means to be 'prepared for luck' in the scientific context. Research is showing that scientists are taught various heuristics that tend to harness chance and the unexpected.<ref name="DunbarLuck"/><ref name="Oliver, J.E. 1991">{{cite book |last=Oliver |first=J. E. |year=1991 |chapter=Ch. 2: Strategy for Discovery |title=The Incomplete Guide to the Art of Discovery |place=New York |publisher=Columbia University Press |isbn=9780231076203}}</ref> This is what [[Nassim Nicholas Taleb]] calls "Anti-fragility"; while some systems of investigation are fragile in the face of [[human error]], human bias, and randomness, the scientific method is more than resistant or tough – it actually benefits from such randomness in many ways (it is anti-fragile). Taleb believes that the more anti-fragile the system, the more it will flourish in the real world.<ref name=Anti-fragility>{{cite web |last=Taleb |first=Nassim N. |title=Antifragility — or — The Property Of Disorder-Loving Systems |url=http://www.edge.org/q2011/q11_3.html |url-status=dead |archive-date=2013-05-07 |archive-url=https://web.archive.org/web/20130507124322/http://www.edge.org/q2011/q11_3.html}}</ref>

{{anchor|startWithBugs}}Psychologist Kevin Dunbar says the process of discovery often starts with researchers finding bugs in their experiments. These unexpected results lead researchers to try to fix what they ''think'' is an error in their method. Eventually, the researcher decides the error is too persistent and systematic to be a coincidence. The highly controlled, cautious, and curious aspects of the scientific method are thus what make it well suited for identifying such persistent systematic errors. At this point, the researcher will begin to think of theoretical explanations for the error, often seeking the help of colleagues across different domains of expertise.<ref name="DunbarLuck"/><ref name="Oliver, J.E. 1991"/>

=== Relationship with statistics ===
When the scientific method employs statistics as a key part of its arsenal, there are mathematical and practical issues that can have a deleterious effect on the reliability of the output of scientific methods. This is described in a popular 2005 scientific paper "[[Why Most Published Research Findings Are False]]" by [[John Ioannidis]], which is considered foundational to the field of [[metascience]].<ref name="mostRwrong">{{Cite journal|title = Why Most Published Research Findings Are False|journal = PLOS Medicine|date = 2005-08-01|issn = 1549-1277|pmc = 1182327|pmid = 16060722|volume = 2|issue = 8|pages = e124|doi = 10.1371/journal.pmed.0020124|first = John P.A.|last = Ioannidis | doi-access=free }}</ref> Much research in metascience seeks to identify poor use of statistics and improve its use, an example being the [[misuse of p-values]].<ref>{{cite journal| url = https://pubs.asahq.org/anesthesiology/article/60/5/505/29253/Regarding-the-Misuse-of-t-Tests| title = Regarding the Misuse of ''t'' Tests| journal = Anesthesiology| date = May 1984| volume = 60| issue = 5| pages = 505| doi = 10.1097/00000542-198405000-00026| last1 = Schaefer| first1 = Carl F| pmid = 6711862| access-date = 2021-08-29 | archive-date = 2021-08-29 | archive-url = https://web.archive.org/web/20210829012031/https://pubs.asahq.org/anesthesiology/article/60/5/505/29253/Regarding-the-Misuse-of-t-Tests| url-status = live| doi-access = free}}</ref>

The particular points raised are statistical ("The smaller the studies conducted in a scientific field, the less likely the research findings are to be true" and "The greater the flexibility in designs, definitions, outcomes, and analytical modes in a scientific field, the less likely the research findings are to be true.") and economical ("The greater the financial and other interests and prejudices in a scientific field, the less likely the research findings are to be true" and "The hotter a scientific field (with more scientific teams involved), the less likely the research findings are to be true.") Hence: "Most research findings are false for most research designs and for most fields" and "As shown, the majority of modern biomedical research is operating in areas with very low pre- and poststudy probability for true findings." However: "Nevertheless, most new discoveries will continue to stem from hypothesis-generating research with low or very low pre-study odds," which means that *new* discoveries will come from research that, when that research started, had low or very low odds (a low or very low chance) of succeeding. Hence, if the scientific method is used to expand the frontiers of knowledge, research into areas that are outside the mainstream will yield the newest discoveries.<ref name="mostRwrong"/>{{copy edit inline|reason=this paragraph consists of many quotations that are not worked into the text very well.|date=April 2024}}

===Science of complex systems===
Science applied to complex systems can involve elements such as [[transdisciplinarity]], [[systems theory]], [[control theory#Open-loop and closed-loop (feedback) control|control theory]], and [[scientific modelling]].

In general, the scientific method may be difficult to apply stringently to diverse, interconnected systems and large data sets. In particular, practices used within [[Big data]], such as [[predictive analytics]], may be considered to be at odds with the scientific method,<ref>Anderson, Chris (2008) [http://www.uvm.edu/~pdodds/files/papers/others/2008/anderson2008a.pdf The End of Theory: The Data Deluge Makes the Scientific Method Obsolete] {{Webarchive|url=https://web.archive.org/web/20210502005844/http://www.uvm.edu/pdodds/files/papers/others/2008/anderson2008a.pdf |date=2021-05-02  }}. Wired Magazine 16.07</ref> as some of the data may have been stripped of the parameters which might be material in alternative hypotheses for an explanation; thus the stripped data would only serve to support the [[null hypothesis]] in the predictive analytics application. {{harvp| Fleck| 1979 |pp=38–50}} notes "a [[#startWithBugs|scientific discovery remains incomplete without considerations of the social practices]] that condition it".<ref name= bigDataCanBeIncomplete>[[Ludwik Fleck]] (1979) ''[https://worldpece.org/sites/default/files/artifacts/media/pdf/fleck_et_al._-_2008_-_genesis_and_development_of_a_scientific_fact.pdf Genesis and Development of a Scientific Fact] {{Webarchive|url=https://web.archive.org/web/20210826194119/https://worldpece.org/sites/default/files/artifacts/media/pdf/fleck_et_al._-_2008_-_genesis_and_development_of_a_scientific_fact.pdf |date=2021-08-26  }}''</ref>

==Relationship with mathematics==
Science is the process of gathering, comparing, and evaluating proposed models against [[observable]]s. {{anchor|aModel}}A model can be a simulation, mathematical or chemical formula, or set of proposed steps. Science is like mathematics in that researchers in both disciplines try to distinguish what is ''known'' from what is ''unknown'' at each stage of discovery. Models, in both science and mathematics, need to be internally consistent and also ought to be ''[[falsifiable]]'' (capable of disproof). In mathematics, a statement need not yet be proved; at such a stage, that statement would be called a [[conjecture]].<ref>{{harvp|Pólya|1957|p=131}} in the section on 'Modern [[heuristic]]':
"When we are working intensively, we feel keenly the progress of our work; we are elated when our progress is rapid, we are depressed when it is slow."</ref>

Mathematical work and scientific work can inspire each other.<ref name= ilSaggiatore >
"Philosophy [i.e., physics] is written in this grand book – I mean the universe – which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it; without these, one is wandering around in a dark labyrinth." – Galileo Galilei, ''Il Saggiatore'' (''[[The Assayer]]'', 1623), as translated by [[Stillman Drake]] (1957), ''Discoveries and Opinions of Galileo'' pp. 237–238,
as quoted by {{harvp|di Francia|1981|p=10}}.
</ref> For example, the technical concept of [[time]] arose in [[science]], and timelessness was a hallmark of a mathematical topic. But today, the [[Poincaré conjecture]] has been proved using time as a mathematical concept in which objects can flow (see [[Ricci flow]]).<ref>Huai-Dong Cao and Xi-Ping Zhu [https://arxiv.org/pdf/math/0612069.pdf (3 Dec 2006) Hamilton-Perelman’s Proof of the Poincaré Conjecture and the Geometrization Conjecture] 
*revised from H.D.Cao and X.P.Zhu ''Asian J. Math.'', '''10'''(2) (2006), 165–492.</ref>

Nevertheless, the connection between mathematics and reality (and so science to the extent it describes reality) remains obscure. [[Eugene Wigner]]'s paper, "[[The Unreasonable Effectiveness of Mathematics in the Natural Sciences]]", is a very well-known account of the issue from a Nobel Prize-winning physicist. In fact, some observers (including some well-known mathematicians such as [[Gregory Chaitin]], and others such as [[Where Mathematics Comes From|Lakoff and Núñez]]) have suggested that mathematics is the result of practitioner bias and human limitation (including cultural ones), somewhat like the post-modernist view of science.<ref name= WMCF >George Lakoff and Rafael E. Núñez (2000) [[Where Mathematics Comes From]] </ref>

[[George Pólya]]'s work on [[problem solving]],<ref name= findIt >"If you can't solve a problem, then there is an easier problem you can solve: find it." —{{harvp|Pólya|1957|p=114}}</ref> the construction of mathematical [[Mathematical proof|proofs]], and [[heuristic]]<ref>
George Pólya (1954), ''Mathematics and Plausible Reasoning Volume I: Induction and Analogy in Mathematics''.
</ref><ref>
George Pólya (1954), ''Mathematics and Plausible Reasoning Volume II: Patterns of Plausible Reasoning''.
</ref> show that the mathematical method and the scientific method differ in detail, while nevertheless resembling each other in using iterative or recursive steps.

{| class="wikitable"
|-
|
!scope="col"|[[How to Solve It|Mathematical method]]
!scope="col"|[[#Elements of the scientific method|Scientific method]]
|-
!scope="row"|1
| [[Understanding]]
| [[#Characterizations|Characterization from experience and observation]]
|-
!scope="row"|2
| [[Analysis]]
| [[#Hypothesis development|Hypothesis: a proposed explanation]]
|-
!scope="row"|3
| [[wikt:synthesis|Synthesis]]
| [[#Predictions from the hypothesis|Deduction: prediction from the hypothesis]]
|-
!scope="row"|4
| [[Review]]/[[Generalization|Extend]]
| [[#Experiments|Test and experiment]]
|}
{{anchor|polyaFirstUnderstand}}
In Pólya's view, ''understanding'' involves restating unfamiliar definitions in your own words, resorting to geometrical figures, and questioning what we know and do not know already; ''analysis'', which Pólya takes from [[Pappus of Alexandria|Pappus]],{{sfnp|Pólya|1957|p=142}} involves free and heuristic construction of plausible arguments, [[working backward from the goal]], and devising a plan for constructing the proof; ''synthesis'' is the strict [[Euclid]]ean exposition of step-by-step details{{sfnp|Pólya|1957|p=144}} of the proof; ''review'' involves reconsidering and re-examining the result and the path taken to it.

{{anchor|proofsAndRefutations}}Building on Pólya's work, [[Imre Lakatos]] argued that mathematicians actually use contradiction, criticism, and revision as principles for improving their work.<ref>{{harvp|Lakatos|1976}} documents the development, by generations of mathematicians, of [[Euler's formula for polyhedra]].</ref>{{efn-lg|name= stillwell'sReviewOfGray'sBioOfPoincaré}} In like manner to science, where truth is sought, but certainty is not found, in ''[[Proofs and Refutations]]'', what Lakatos tried to establish was that no theorem of [[informal mathematics]] is final or perfect. This means that, in non-axiomatic mathematics, we should not think that a theorem is ultimately true, only that no [[counterexample]] has yet been found. Once a counterexample, i.e. an entity contradicting/not explained by the theorem is found, we adjust the theorem, possibly extending the domain of its validity. This is a continuous way our knowledge accumulates, through the logic and process of proofs and refutations. (However, if axioms are given for a branch of mathematics, this creates a logical system —Wittgenstein 1921 ''Tractatus Logico-Philosophicus'' 5.13; Lakatos claimed that proofs from such a system were [[Tautology (logic)|tautological]], i.e. [[logical truth|internally logically true]], by [[string rewriting system|rewriting forms]], as shown by Poincaré, who demonstrated the technique of transforming tautologically true forms (viz. the [[Euler characteristic]]) into or out of forms from [[homology (mathematics)|homology]],<ref name= eulerPoincaré >H.S.M. Coxeter (1973) ''Regular Polytopes'' {{ISBN| 9780486614809}}, Chapter IX "Poincaré's proof of Euler's formula"</ref> or more abstractly, from [[homological algebra]].<ref>{{cite web| url = https://faculty.math.illinois.edu/K-theory/0245/survey.pdf| title = Charles A. Weibel (ca. 1995) History of Homological Algebra| access-date = 2021-08-28 | archive-date = 2021-09-06 | archive-url = https://web.archive.org/web/20210906014123/https://faculty.math.illinois.edu/K-theory/0245/survey.pdf| url-status = live}}</ref><ref>Henri Poincaré, Sur l’[[Analysis Situs (paper)|analysis situs]], ''Comptes rendusde l’Academie des Sciences'' '''115''' (1892), 633–636. as cited by {{harvp| Lakatos| 1976 |p=162}}</ref>{{efn-lg|name= stillwell'sReviewOfGray'sBioOfPoincaré|Stillwell's review (p. 381) of Poincaré's efforts on the [[Euler characteristic]] notes that it took ''five'' iterations for Poincaré to arrive at the ''[[homology sphere#Poincaré homology sphere|Poincaré homology sphere]]''.<ref name= stillwell>John Stillwell, reviewer (Apr 2014). ''Notices of the AMS.'' '''61''' (4), pp. 378–383, on Jeremy Gray's (2013) ''Henri Poincaré: A Scientific Biography'' ([http://www.ams.org/notices/201404/rnoti-p378.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20210704205514/http://www.ams.org/notices/201404/rnoti-p378.pdf |date=2021-07-04  }}).</ref>}}

Lakatos proposed an account of mathematical knowledge based on Polya's idea of [[heuristic]]s. In ''Proofs and Refutations'', Lakatos gave several basic rules for finding proofs and counterexamples to conjectures. He thought that mathematical '[[thought experiment]]s' are a valid way to discover mathematical conjectures and proofs.{{sfnp|Lakatos|1976|p=55}}

[[Carl Friedrich Gauss|Gauss]], when asked how he came about his [[theorem]]s, once replied "durch planmässiges Tattonieren" (through [[Constructivism (mathematics)|systematic palpable experimentation]]).{{sfnp|Mackay|1991|p=100}}

==See also==
* {{Annotated link|Empirical limits in science}}
* {{Annotated link|Evidence-based practices}}
* {{Annotated link|Methodology}}
* {{Annotated link|Metascience}}
* [[Outline of scientific method]]
* {{Annotated link|Quantitative research}}
* [[Research transparency]]
* {{Annotated link|Scientific law}}
* {{Annotated link|Testability}}
<!--* {{Annotated link|Sociology of scientific knowledge}}
* {{Annotated link|Models of scientific inquiry}}
* {{Annotated link|Timeline of the history of scientific method}}-->

==Notes==
{{Notelist|33em}}

===Notes: Problem-solving via scientific method<!--Examples of the method of science-->===
{{Notelist-ua|33em}}
{{Notelist-lr|33em}}

===Notes: Philosophical expressions of method===
{{Notelist-lg|33em}}

==References==
{{Reflist | group= Note}}
{{Reflist}}

==Sources==
{{Refbegin|33em |indent=yes}}
* {{cite book |last1=Alikuzai |first1=Hamid Wahed |title=A Concise History of Afghanistan in 25 Volumes |date=2013 |publisher=Trafford Publishing |isbn=978-1-4907-1446-2 |page= |edition= |volume=1 |url=https://books.google.com/books?id=-WRlAQAAQBAJ |access-date=2023-06-03  |archive-date=2023-11-29  |archive-url=https://web.archive.org/web/20231129112737/https://books.google.com/books?id=-WRlAQAAQBAJ |url-status=live }}
* {{citation |last=Borlik |first=Todd Andrew |contribution='More than Art': Clockwork Automata, the Extemporizing Actor, and the Brazen Head in ''Friar Bacon and Friar Bungay'' |title=The Automaton in English Renaissance Literature |url = https://books.google.com/books?id=c_ShAgAAQBAJ |editor-last=Hyman |editor-first=Wendy Beth |display-editors=0 |publisher=Ashgate Publishing |location=Farnham |year = 2011 |isbn = 978-0-7546-6865-7 |contribution-url = https://books.google.com/books?id=c_ShAgAAQBAJ }}
* {{Citation|first=Max|last=Born|author-link=Max Born|year=1949|title=Natural Philosophy of Cause and Chance|publisher=Peter Smith}}, also published by Dover, 1964. From the Waynflete Lectures, 1948. [https://archive.org/stream/naturalphilosoph032159mbp/naturalphilosoph032159mbp_djvu.txt On the web. N.B.: the web version does not have the 3 addenda by Born, 1950, 1964, in which he notes that all knowledge is subjective. Born then proposes a solution in Appendix 3 (1964)]
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{{Refend}}

==Further reading==
{{Refbegin|33em |indent=yes}}
* [[Henry H. Bauer|Bauer, Henry H.]], ''Scientific Literacy and the Myth of the Scientific Method'', University of Illinois Press, Champaign, IL, 1992
* [[William Ian Beardmore Beveridge|Beveridge, William I.B.]], ''The Art of Scientific Investigation'', [[Heinemann (book publisher)|Heinemann]], Melbourne, Australia, 1950.
* [[Richard J. Bernstein|Bernstein, Richard J.]], ''Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis'', University of Pennsylvania Press, Philadelphia, PA, 1983.
* [[Baruch A. Brody|Brody, Baruch A.]] and Capaldi, Nicholas, [https://books.google.com/books?id=d1heAAAAIAAJ ''Science: Men, Methods, Goals: A Reader: Methods of Physical Science''] {{Webarchive|url=https://web.archive.org/web/20230413233902/https://books.google.com/books?id=d1heAAAAIAAJ |date=2023-04-13  }}, W.A. Benjamin, 1968
* [[Baruch A. Brody|Brody, Baruch A.]] and [[Richard Grandy|Grandy, Richard E.]], ''Readings in the Philosophy of Science'', 2nd edition, Prentice-Hall, Englewood Cliffs, NJ, 1989.
* [[Arthur W. Burks|Burks, Arthur W.]], ''Chance, Cause, Reason: An Inquiry into the Nature of Scientific Evidence'', University of Chicago Press, Chicago, IL, 1977.
* [[Alan Chalmers|Chalmers, Alan]], ''[[What Is This Thing Called Science?]]''. Queensland University Press and Open University Press, 1976. 
* {{citation |last=Crick|first=Francis|author-link=Francis Crick|title=What Mad Pursuit: A Personal View of Scientific Discovery|year=1988|location=New York|publisher=Basic Books|isbn=978-0-465-09137-9|title-link=What Mad Pursuit: A Personal View of Scientific Discovery}}.
* {{citation |first= A.C.  |last= Crombie | title= Robert Grosseteste and the Origins of Experimental Science 1100–1700 | location= Oxford |year= 1953 |publisher=Clarendon}}
* [[John Earman|Earman, John]] (ed.), ''Inference, Explanation, and Other Frustrations: Essays in the Philosophy of Science'', University of California Press, Berkeley & Los Angeles, CA, 1992.
* [[Bas C. van Fraassen|Fraassen, Bas C. van]], ''The Scientific Image'', Oxford University Press, Oxford, 1980.
* {{Citation|last=Franklin |first=James |author-link=James Franklin (philosopher) |year=2009|title=What Science Knows: And How It Knows It|location=New York|publisher=Encounter Books| isbn=978-1-59403-207-3}}.
* [[Hans-Georg Gadamer|Gadamer, Hans-Georg]], ''Reason in the Age of Science'', Frederick G. Lawrence (trans.), MIT Press, Cambridge, MA, 1981.
* [[Ronald N. Giere|Giere, Ronald N.]] (ed.), ''Cognitive Models of Science'', vol. 15 in 'Minnesota Studies in the Philosophy of Science', University of Minnesota Press, Minneapolis, MN, 1992.
* [[Ian Hacking|Hacking, Ian]], ''Representing and Intervening, Introductory Topics in the Philosophy of Natural Science'', Cambridge University Press, Cambridge, 1983.
* [[Werner Heisenberg|Heisenberg, Werner]], ''Physics and Beyond, Encounters and Conversations'', A.J. Pomerans (trans.), Harper and Row, New York, 1971, pp.&nbsp;63–64.
* [[Gerald Holton|Holton, Gerald]], ''[[Thematic Origins of Scientific Thought: Kepler to Einstein]]'', 1st edition 1973, revised edition, Harvard University Press, Cambridge, MA, 1988.
* [[Karin Knorr Cetina]], {{cite book | last = Knorr Cetina | first = Karin | title = Epistemic cultures: how the sciences make knowledge | publisher = Harvard University Press | location = Cambridge, Massachusetts | year = 1999 | isbn = 978-0-674-25894-5 | title-link = Epistemic cultures }}
* [[Thomas S. Kuhn|Kuhn, Thomas S.]], ''The Essential Tension, Selected Studies in Scientific Tradition and Change'', University of Chicago Press, Chicago, IL, 1977.
* [[Bruno Latour|Latour, Bruno]], ''Science in Action, How to Follow Scientists and Engineers through Society'', Harvard University Press, Cambridge, MA, 1987.
* Losee, John, ''A Historical Introduction to the Philosophy of Science'', Oxford University Press, Oxford, 1972. 2nd edition, 1980.
* [[Nicholas Maxwell|Maxwell, Nicholas]], ''The Comprehensibility of the Universe: A New Conception of Science'', Oxford University Press, Oxford, 1998. Paperback 2003.
* [[Nicholas Maxwell|Maxwell, Nicholas]], [http://www.paragonhouse.com/xcart/Understanding-Scientific-Progress-Aim-Oriented-Empiricism.html ''Understanding Scientific Progress''] {{Webarchive|url=https://web.archive.org/web/20180220210819/http://www.paragonhouse.com/xcart/Understanding-Scientific-Progress-Aim-Oriented-Empiricism.html |date=2018-02-20  }}, Paragon House, St. Paul, Minnesota, 2017.
* {{cite web |editor-link=William McComas |editor-last=McComas |editor-first=William F. |title=The Principal Elements of the Nature of Science: Dispelling the Myths |work=The Nature of Science in Science Education |pages=53–70 |publisher=Kluwer Academic Publishers |place=Netherlands |year=1998 |url=http://coehp.uark.edu/pase/TheMythsOfScience.pdf |url-status=dead |archive-date=2014-07-01 |archive-url=https://web.archive.org/web/20140701110930/http://coehp.uark.edu/pase/TheMythsOfScience.pdf }}
* [[Cheryl Misak|Misak, Cheryl J.]], ''Truth and the End of Inquiry, A Peircean Account of Truth'', Oxford University Press, Oxford, 1991.
* [[Naomi Oreskes|Oreskes, Naomi]], "Masked Confusion: A trusted source of health information misleads the public by prioritizing rigor over reality", ''[[Scientific American]]'', vol. 329, no. 4 (November 2023), pp.&nbsp;90–91.
* Piattelli-Palmarini, Massimo (ed.), ''Language and Learning, The Debate between Jean Piaget and Noam Chomsky'', Harvard University Press, Cambridge, MA, 1980.
* [[Karl R. Popper|Popper, Karl R.]], ''Unended Quest, An Intellectual Autobiography'', Open Court, La Salle, IL, 1982.
* [[Hilary Putnam|Putnam, Hilary]], ''Renewing Philosophy'', Harvard University Press, Cambridge, MA, 1992.
* [[Richard Rorty|Rorty, Richard]], ''Philosophy and the Mirror of Nature'', Princeton University Press, Princeton, NJ, 1979.
* [[Wesley C. Salmon|Salmon, Wesley C.]], ''Four Decades of Scientific Explanation'', University of Minnesota Press, Minneapolis, MN, 1990.
* [[Abner Shimony|Shimony, Abner]], ''Search for a Naturalistic World View: Vol. 1, Scientific Method and Epistemology, Vol. 2, Natural Science and Metaphysics'', Cambridge University Press, Cambridge, 1993.
* [[Paul Thagard|Thagard, Paul]], ''Conceptual Revolutions'', Princeton University Press, Princeton, NJ, 1992.
* [[John Ziman|Ziman, John]] (2000). ''Real Science: what it is, and what it means''. Cambridge: Cambridge University Press.
{{Refend}}

==External links==
{{Commons category}}
{{Wikibooks|The Scientific Method}}
{{Wikiversity|Thinking Scientifically}}
{{Library resources box
|by=no
|onlinebooks=no
|others=no
|about=yes
|label=Scientific method}}
* {{cite SEP |url-id=scientific-method |title=Scientific Method |last=Andersen |first=Hanne|author-link=Hanne Andersen (philosopher)|last2=Hepburn |first2=Brian}}
* {{cite IEP |url-id=conf-ind |title=Confirmation and Induction}}
* {{PhilPapers|category|scientific-method}}
* {{InPho|idea|1916}}
* [http://www.geo.sunysb.edu/esp/files/scientific-method.html An Introduction to Science: Scientific Thinking and a scientific method] {{Webarchive|url=https://web.archive.org/web/20180101173949/http://www.geo.sunysb.edu/esp/files/scientific-method.html |date=2018-01-01  }} by Steven D. Schafersman.
* [http://teacher.nsrl.rochester.edu/phy_labs/AppendixE/AppendixE.html Introduction to the scientific method] at the [[University of Rochester]]
* [http://zenodo.org/record/6336021#.YmafclMpBKM The scientific method from a philosophical perspective]
* [http://www.galilean-library.org/theory.html Theory-ladenness] by Paul Newall at The Galilean Library
* [https://web.archive.org/web/20060428080832/http://pasadena.wr.usgs.gov/office/ganderson/es10/lectures/lecture01/lecture01.html Lecture on Scientific Method by Greg Anderson] (archived 28 April 2006)
* [http://www.sciencemadesimple.com/scientific_method.html Using the scientific method for designing science fair projects]
* [http://emotionalcompetency.com/sci/booktoc.html ''Scientific Methods'' an online book by Richard D. Jarrard]
* [https://www.youtube.com/watch?v=b240PGCMwV0 Richard Feynman on the Key to Science] (one minute, three seconds), from the Cornell Lectures.
* [https://archive.today/20130121134726/http://www.dbskeptic.com/2010/03/14/what-it-means-to-be-scientifically-proven/ Lectures on the Scientific Method] by Nick Josh Karean, [[Kevin Padian]], [[Michael Shermer]] and [[Richard Dawkins]] (archived 21 January 2013).
* [https://www.youtube.com/watch?v=Yk5IWzTfWeM "How Do We Know What Is True?" (animated video; 2:52)]

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[[Category:Scientific Revolution|Method]]
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