Editing Scientific theory (section)

{{Short description|Explanation of some aspect of the natural world which can be tested and corroborated}}
{{Use dmy dates|date=September 2023}}
{{Broader|Theory}}

A '''scientific theory''' is an explanation of an aspect of the [[universe|natural world]] that can be or that has been [[reproducibility|repeatedly tested]] and has [[corroborating evidence]] in accordance with the [[scientific method]], using accepted [[protocol (science)|protocols]] of [[observation]], measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an [[experiment]].<ref name="NAS1999">{{cite book |url=https://archive.org/details/sciencecreationi0000unse/page/2 |title=Science and Creationism: A View from the National Academy of Sciences |publisher=[[National Academy of Sciences|National Academies Press]] |year=1999 |edition=2nd |page=[https://archive.org/details/sciencecreationi0000unse/page/2 2] |doi=10.17226/6024 |pmid=25101403 |isbn=978-0-309-06406-4 |author1=National Academy of Sciences (US) }}</ref><ref name="The Structure of Scientific Theories in ''The Stanford Encyclopedia of Philosophy''">{{cite encyclopedia |url=http://plato.stanford.edu/entries/structure-scientific-theories/ |last=Winther |first=Rasmus G. |title=The Structure of Scientific Theories |encyclopedia=The Stanford Encyclopedia of Philosophy|publisher=Metaphysics Research Lab, Stanford University |year=2016 }}</ref> In circumstances not amenable to experimental testing, theories are evaluated through principles of [[abductive reasoning]]. Established scientific theories have withstood rigorous scrutiny and embody scientific [[knowledge]].

A scientific theory differs from a [[scientific fact]]: a fact is an observation and a theory organizes and explains multiple observations. Furthermore, a theory is expected to make predictions which could be confirmed or refuted with addition observations. [[Stephen Jay Gould]] wrote that "...facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts."<ref>Gould, Stephen Jay. [https://www.inf.fu-berlin.de/lehre/pmo/eng/Gould-Fact&Theory.pdf "Evolution as fact and theory."] Discover 2.5 (1981): 34-37. Reprinted in ''Hen's Teeth and Horse's Toes,'' New York: W. W. Norton & Company, 1994, pp. 253-262. ISBN 9780393340860 </ref>
A theory differs from a [[scientific law]] in that a law is an empirical description of a relationship between facts and/or other laws. For example, [[Newton's law of universal gravitation|Newton's Law of Gravity]] is a mathematical equation that can be used to predict the attraction between bodies, but it is not a theory to explain ''how'' [[gravity]] works.<ref>{{Cite web |last1=Bradford |first1=Alina |last2=Hamer |first2=Ashley |date=July 2017 |title=What Is a Scientific Theory? |url=https://www.livescience.com/21491-what-is-a-scientific-theory-definition-of-theory.html|access-date=2021-01-17 |publisher=Live Science |language=en}}</ref>

The meaning of the term ''scientific theory'' (often contracted to ''theory'' for brevity) as used in the [[Branches of science|disciplines of science]] is significantly different from the common [[vernacular]] usage of ''theory''.<ref name="NAS2008" /> In everyday speech, ''theory'' can imply an explanation that represents an unsubstantiated and speculative [[conjecture|guess]],<ref name="NAS2008">{{cite web |url=http://nationalacademies.org/evolution/TheoryOrFact.html |title=Is Evolution a Theory or a Fact? |publisher=[[National Academy of Sciences]] |year=2008|archive-url=https://web.archive.org/web/20190907174218/http://nationalacademies.org/evolution/TheoryOrFact.html |archive-date=2019-09-07}}</ref> whereas in a scientific context it most often refers to an explanation that has already been tested and is widely accepted as valid.<ref name="NAS1999"/><ref name="The Structure of Scientific Theories in ''The Stanford Encyclopedia of Philosophy''"/>

The strength of a scientific theory is related to the diversity of phenomena it can explain and its simplicity. As additional [[scientific evidence]] is gathered, a scientific theory may be modified and ultimately rejected if it cannot be made to fit the new findings; in such circumstances, a more accurate theory is then required. Some theories are so well-established that they are unlikely ever to be fundamentally changed (for example, scientific theories such as [[evolution]], [[Heliocentrism|heliocentric theory]], [[cell theory]], [[Plate tectonics|theory of plate tectonics]], [[germ theory of disease]], etc.). In certain cases, a scientific theory or scientific law that fails to fit all data can still be useful (due to its simplicity) as an approximation under specific conditions. An example is [[Newton's laws of motion]], which are a highly accurate approximation to [[special relativity]] at velocities that are small relative to the [[speed of light]].<ref name="Misner1973"/><ref name=Weinberg/><ref name=Project2061/>

Scientific theories are [[testability|testable]] and make verifiable [[prediction in science|predictions]].<ref name=Popper/> They describe the causes of a particular natural phenomenon and are used to explain and predict aspects of the physical [[universe]] or specific areas of inquiry (for example, electricity, chemistry, and astronomy). As with other forms of scientific knowledge, scientific theories are both [[deductive reasoning|deductive]] and [[inductive reasoning|inductive]],<ref>{{cite encyclopedia |author1=Andersen, Hanne |author2=Hepburn, Brian |title=Scientific Method |encyclopedia=The Stanford Encyclopedia of Philosophy |year=2015 |editor=Edward N. Zalta |url=http://plato.stanford.edu/archives/win2015/entries/scientific-method/}}</ref> aiming for [[predictive power|predictive]] and [[explanatory power]]. Scientists use theories to further scientific knowledge, as well as to facilitate advances in [[technology]] or [[medicine]]. Scientific hypotheses can never be "proven" because scientists are not able to fully confirm that their hypothesis is true. Instead, scientists say that the study "supports" or is consistent with their hypothesis.<ref>{{cite book |last1=Morling |title=Research Methods in Psychology |pages=12}}</ref>