Editing History of logic (section)

====The Organon====
His logical works, called the ''[[Organon]]'', are the earliest formal study of logic that have come down to modern times. Though it is difficult to determine the dates, the probable order of writing of Aristotle's logical works is:
* ''[[Categories (Aristotle)|The Categories]]'', a study of the ten kinds of primitive term.
* ''[[Topics (Aristotle)|The Topics]]'' (with an appendix called ''[[On Sophistical Refutations]]''), a discussion of dialectics.
* ''[[De Interpretatione|On Interpretation]]'', an analysis of simple [[categorical proposition]]s into simple terms, negation, and signs of quantity. 
* ''[[Prior Analytics|The Prior Analytics]]'', a formal analysis of what makes a [[syllogism]] (a valid argument, according to Aristotle).
* ''[[Posterior Analytics|The Posterior Analytics]]'', a study of scientific demonstration, containing Aristotle's mature views on logic.
[[File:Square of opposition, set diagrams.svg|thumb|180px|This diagram shows the contradictory relationships between [[categorical proposition]]s in the [[square of opposition]] of [[Term logic|Aristotelian logic]].]]
These works are of outstanding importance in the history of logic. In the ''Categories'', he attempts to discern all the possible things to which a term can refer; this idea underpins his philosophical work ''[[Metaphysics (Aristotle)|Metaphysics]]'', which itself had a profound influence on Western thought.

He also developed a theory of non-formal logic (''i.e.,'' the theory of [[logical fallacy|fallacies]]), which is presented in ''Topics'' and ''Sophistical Refutations''.<ref name="Bochenski p. 63"/>

''On Interpretation'' contains a comprehensive treatment of the notions of [[Square of opposition|opposition]] and conversion; chapter 7 is at the origin of the [[square of opposition]] (or logical square); chapter 9 contains the beginning of [[modal logic]].

The ''Prior Analytics'' contains his exposition of the "syllogism", where three important principles are applied for the first time in history: the use of variables, a purely formal treatment, and the use of an axiomatic system.