Aristotle

=== Logic ===
{{Main|Term logic}}
{{further | Non-Aristotelian logic}}

With the ''[[Prior Analytics]]'', Aristotle is credited with the earliest study of formal logic,{{sfn| Degnan | 1994 | pp=81–89}} and his conception of it was the dominant form of Western logic until 19th-century advances in [[mathematical logic]].{{sfn| Corcoran | 2009 | pp=1–20}} [[Immanuel Kant|Kant]] stated in the ''[[Critique of Pure Reason]]'' that with Aristotle, logic reached its completion.{{sfn| Kant | 1787 | pages=Preface}}

==== ''Organon'' ====
{{Main|Organon}}
{| class="wikitable floatright"
|+ One of Aristotle's [[Syllogism#Types|types of syllogism]]{{efn-ua|This [[Syllogism#Types|type of syllogism]], with all three terms in 'a', is known by the traditional (medieval) [[mnemonic]] [[Baralipton|Barbara]].{{sfn|Lagerlund|2016}}}}
! In words !! In<br /> terms{{efn-ua|M is the Middle (here, Men), S is the Subject (Greeks), P is the Predicate (mortal).{{sfn|Lagerlund|2016}}}} !! In equations{{efn-ua|The first equation can be read as 'It is not true that there exists an x such that x is a man and that x is not mortal.'{{sfn|Predicate Logic}}}}
|-
|&nbsp;&nbsp;&nbsp;&nbsp;All men are mortal.<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;All Greeks are men.<br /><br />[[Therefore sign|∴]] All Greeks are mortal.||M a P<br /><br />S a M<br /><br />S a P||[[File:Modus Barbara Equations.svg|180px]]
|}

What is today called ''Aristotelian logic'' with its [[Syllogism#Types|types of syllogism]] (methods of logical argument),{{sfn| Lagerlund | 2016}} Aristotle himself would have labelled "analytics". The term "logic" he reserved to mean ''dialectics''. Most of Aristotle's work is probably not in its original form, because it was most likely edited by students and later lecturers. The logical works of Aristotle were compiled into a set of six books called the ''[[Organon]]'' around 40 BC by [[Andronicus of Rhodes]] or others among his followers.{{sfn| Pickover | 2009 | page=52}} The books are:
# ''[[Categories (Aristotle)|Categories]]''
# ''[[On Interpretation]]''
# ''[[Prior Analytics]]''
# ''[[Posterior Analytics]]''
# ''[[Topics (Aristotle)|Topics]]''
# ''[[On Sophistical Refutations]]''

[[File:Sanzio 01 Plato Aristotle.jpg| thumb | upright | [[Plato]] (left) and Aristotle in [[Raphael]]'s 1509 fresco, ''[[The School of Athens]]''. Aristotle holds his ''[[Nicomachean Ethics]]'' and gestures to the earth, representing his view in immanent realism, whilst Plato gestures to the heavens, indicating his Theory of Forms, and holds his ''[[Timaeus (dialogue)|Timaeus]]''.{{sfn| School of Athens}}{{sfn|Stewart|2019}}]]
The order of the books (or the teachings from which they are composed) is not certain, but this list was derived from analysis of Aristotle's writings. It goes from the basics, the analysis of simple terms in the ''Categories,'' the analysis of propositions and their elementary relations in ''On Interpretation'', to the study of more complex forms, namely, syllogisms (in the ''Analytics''){{sfn| Prior Analytics | pp= 24b18–20}}{{sfn| Bobzien | 2015}} and dialectics (in the ''Topics'' and ''Sophistical Refutations''). The first three treatises form the core of the logical theory ''stricto sensu'': the grammar of the language of logic and the correct rules of reasoning. The ''Rhetoric'' is not conventionally included, but it states that it relies on the ''Topics''.{{sfn| Smith | 2017}}