Reason

==Reason in particular fields of study==

===Psychology and cognitive science===
{{See also|Psychology of reasoning}}
Scientific research into reasoning is carried out within the fields of [[psychology]] and [[cognitive science]]. Psychologists attempt to determine whether or not people are capable of rational thought in a number of different circumstances.

Assessing how well someone engages in reasoning is the project of determining the extent to which the person is [[Rationality|rational]] or acts rationally. It is a key research question in the [[psychology of reasoning]] and cognitive science of reasoning. [[Rationality]] is often divided into its respective [[Rationality#Theoretical and practical|theoretical and practical counterparts]].

====Behavioral experiments on human reasoning====
Experimental cognitive psychologists carry out research on reasoning behaviour. Such research may focus, for example, on how people perform on tests of reasoning such as [[Intelligence tests|intelligence]] or [[IQ]] tests, or on how well people's reasoning matches ideals set by logic (see, for example, the [[Wason test]]).<ref>{{cite book|last=Manktelow|first=K.I.|year=1999|title=Reasoning and Thinking (Cognitive Psychology: Modular Course)|location=Hove, Sussex|publisher=Psychology Press}}</ref> Experiments examine how people make inferences from conditionals like ''if A then B'' and how they make inferences about alternatives like ''A or else B''.<ref>{{cite book|last1=Johnson-Laird|first1=P.N.|last2=Byrne|first2=R.M.J.|year=1991|title=Deduction|location=Hillsdale|publisher=Erlbaum}}</ref> They test whether people can make valid deductions about spatial and temporal relations like ''A is to the left of B'' or ''A happens after B'', and about quantified assertions like ''all the A are B''.<ref>{{cite book|last1=Johnson-Laird|first1=P.N.|year=2006|title=How we reason|location=Oxford|publisher=Oxford University Press}}</ref> Experiments investigate how people make inferences about factual situations, hypothetical possibilities, probabilities, and [[counterfactual thinking|counterfactual]] situations.<ref>{{cite book|last=Byrne|first=R.M.J.|year=2005|title=The Rational Imagination: How People Create Counterfactual Alternatives to Reality|location=Cambridge, Mass.|publisher=MIT Press}}</ref>

====Developmental studies of children's reasoning====
Developmental psychologists investigate the development of reasoning from birth to adulthood. Piaget's [[theory of cognitive development]] was the first complete theory of reasoning development. Subsequently, several alternative theories were proposed, including the [[neo-Piagetian theories of cognitive development]].<ref>{{cite book|last=Demetriou|first=A.|year=1998|chapter=Cognitive development|editor-first1=A.|editor-last1=Demetriou|editor-first2=W.|editor-last2=Doise|editor-first3=K.F.M.|editor-last3=van Lieshout|title=Life-span developmental psychology|pages=179–269|location=London|publisher=Wiley}}</ref>

====Neuroscience of reasoning====
{{citation needed section|date=September 2023}}
The biological functioning of the brain is studied by [[neurophysiologist]]s, [[Cognitive neuroscience|cognitive neuroscientists]], and [[neuropsychologist]]s. This includes research into the structure and function of normally functioning brains, and of damaged or otherwise unusual brains. In addition to carrying out research into reasoning, some psychologists—for example [[clinical psychologist]]s and [[psychotherapists]]—work to alter people's reasoning habits when those habits are unhelpful.

===Computer science===

====Automated reasoning====
{{Main|Automated reasoning|Computational logic}}
{{see also|Reasoning system|Case-based reasoning|Semantic reasoner|Knowledge reasoning}}
In [[artificial intelligence]] and [[computer science]], scientists study and use [[automated reasoning]] for diverse applications including [[automated theorem proving]] the [[formal semantics of programming languages]], and [[formal specification]] in [[software engineering]].

====Meta-reasoning====
{{See also|Metacognition}}
'''Meta-reasoning'''<!--boldface per [[WP:R#PLA]]--> is reasoning about reasoning. In computer science, a system performs meta-reasoning when it is reasoning about its own operation.<ref>{{citation|year=2002|volume=2408/2002|issue=65|first=Stefania |last=Costantini |title=Computational Logic: Logic Programming and Beyond |chapter=Meta-reasoning: A Survey |series=Lecture Notes in Computer Science |doi=10.1007/3-540-45632-5_11 |pages=253–288|isbn=978-3540439608}}</ref> This requires a programming language capable of [[reflection (computer science)|reflection]], the ability to observe and modify its own structure and behaviour.

===Evolution of reason===
[[File:Capuchin monkeys sharing.jpg|thumb|right|150px| Dan Sperber believes that reasoning in groups is more effective and promotes their evolutionary fitness.]]
A species could benefit greatly from better abilities to reason about, predict, and understand the world. French social and cognitive scientists [[Dan Sperber]] and Hugo Mercier argue that, aside from these benefits, there could have been other forces driving the evolution of reason. They point out that reasoning is very difficult for humans to do effectively, and that it is hard for individuals to doubt their own beliefs ([[confirmation bias]]). Reasoning is most effective when it is done as a collective—as demonstrated by the success of projects like [[science]]. They suggest that there are not just individual, but [[group selection]] pressures at play. Any group that managed to find ways of reasoning effectively would reap benefits for all its members, increasing their [[fitness (biology)|fitness]]. This could also help explain why humans, according to Sperber, are not optimized to reason effectively alone. Sperber's & Mercier's argumentative theory of reasoning claims that reason may have more to do with winning arguments than with the search for the truth.<ref>{{multiref2
|1={{Cite journal| doi = 10.1017/S0140525X10000968 |pmid = 21447233|url = https://repository.upenn.edu/goldstone/15/| volume = 34| issue = 2| pages = 57–74| last1 = Mercier| first1 = Hugo| last2 = Sperber| first2 = Dan| title = Why Do Humans Reason? Arguments for an Argumentative Theory| journal = Behavioral and Brain Sciences| year = 2011|s2cid = 5669039}}
|2={{Cite book| publisher = Harvard University Press| isbn = 978-0674368309| last1 = Mercier| first1 = Hugo| last2 = Sperber| first2 = Dan| title = The Enigma of Reason| location = Cambridge| year = 2017}}
}}</ref>

===Reason in political philosophy and ethics===
{{Main|Political Philosophy|Ethics|The Good}}
[[Aristotle]] famously described reason (with language) as a part of [[human nature]], because of which it is best for humans to live "politically" meaning in communities of about the size and type of a small [[city state]] ({{transliteration|grc|polis}} in Greek). For example:
{{quote|text=It is clear, then, that a human being is more of a political {{transliteration|grc|politikon}} = of the {{transliteration|grc|polis}}] animal [{{transliteration|grc|zōion}}] than is any bee or than any of those animals that live in herds. For nature, as we say, makes nothing in vain, and humans are the only animals who possess reasoned speech [{{transliteration|grc|logos}}]. Voice, of course, serves to indicate what is painful and pleasant; that is why it is also found in other animals, because their nature has reached the point where they can perceive what is painful and pleasant and express these to each other. But speech [{{transliteration|grc|logos}}] serves to make plain what is advantageous and harmful and so also what is just and unjust. For it is a peculiarity of humans, in contrast to the other animals, to have perception of good and bad, just and unjust, and the like; and the community in these things makes a household or city [{{transliteration|grc|polis}}].... By nature, then, the drive for such a community exists in everyone, but the first to set one up is responsible for things of very great goodness. For as humans are the best of all animals when perfected, so they are the worst when divorced from law and right. The reason is that injustice is most difficult to deal with when furnished with weapons, and the weapons a human being has are meant by nature to go along with prudence and virtue, but it is only too possible to turn them to contrary uses. Consequently, if a human being lacks virtue, he is the most unholy and savage thing, and when it comes to sex and food, the worst. But justice is something political [to do with the {{transliteration|grc|polis}}], for right is the arrangement of the political community, and right is discrimination of what is just.<ref name=Politics>{{cite book|author=[[Aristotle]]|title=[[Politics (Aristotle)|Politics]]|translator-first=Peter|translator-last=Simpson}}</ref>{{rp|at=I.2, 1253a}} }}

If human nature is fixed in this way, we can define what type of community is always best for people. This argument has remained a central argument in all political, ethical, and moral thinking since then, and has become especially controversial since firstly [[Rousseau]]'s Second Discourse, and secondly, the [[Theory of Evolution]]. Already in Aristotle there was an awareness that the {{transliteration|grc|polis}} had not always existed and had to be invented or developed by humans themselves. The household came first, and the first villages and cities were just extensions of that, with the first cities being run as if they were still families with Kings acting like fathers.{{r|Politics|at=I.2, 1252b15}}
<blockquote>[[Friendship]] seems to prevail in man and woman according to [[nature]] [{{transliteration|grc|kata phusin}}]; for people are by nature [{{transliteration|grc|tēi phusei}}] pairing more than political [{{transliteration|grc|politikon}}], in as much as the household [{{transliteration|grc|oikos}}] is prior and more necessary than the {{transliteration|grc|polis}} and making children is more common [{{transliteration|grc|koinoteron}}] with the animals. In the other animals, community [{{transliteration|grc|koinōnia}}] goes no further than this, but people live together [{{transliteration|grc|sumoikousin}}] not only for the sake of making children, but also for the things for life; for from the start the functions [{{transliteration|grc|erga}}] are divided, and are different for man and woman. Thus they supply each other, putting their own into the common [{{transliteration|grc|eis to koinon}}]. It is for these reasons that both utility and pleasure seem to be found in this kind of friendship.{{r|NE|at=[https://standardebooks.org/ebooks/aristotle/nicomachean-ethics/f-h-peters/text/book-8#chapter-8-1-12 VIII.12]}}</blockquote>

[[Rousseau]] in his Second Discourse finally took the shocking step of claiming that this traditional account has things in reverse: with reason, language, and rationally organized communities all having developed over a long period of time merely as a result of the fact that some habits of cooperation were found to solve certain types of problems, and that once such cooperation became more important, it forced people to develop increasingly complex cooperation—often only to defend themselves from each other.

In other words, according to Rousseau, reason, language, and rational community did not arise because of any conscious decision or plan by humans or gods, nor because of any pre-existing human nature. As a result, he claimed, living together in rationally organized communities like modern humans is a development with many negative aspects compared to the original state of man as an ape. If anything is specifically human in this theory, it is the flexibility and adaptability of humans. This view of the animal origins of distinctive human characteristics later received support from [[Charles Darwin]]'s [[Theory of Evolution]].

The two competing theories concerning the origins of reason are relevant to political and ethical thought because, according to the Aristotelian theory, a best way of living together exists independently of historical circumstances. According to Rousseau, we should even doubt that reason, language, and politics are a good thing, as opposed to being simply the best option given the particular course of events that led to today. Rousseau's theory, that human nature is malleable rather than fixed, is often taken to imply (for example by [[Karl Marx]]) a wider range of possible ways of living together than traditionally known.

However, while Rousseau's initial impact encouraged bloody revolutions against traditional politics, including both the [[French Revolution]] and the [[Russian Revolution (1917)|Russian Revolution]], his own conclusions about the best forms of community seem to have been remarkably classical, in favor of city-states such as [[Geneva]], and [[Arcadia (utopia)|rural living]].