Otherwise known as syllogistic logic, and constrasted with propositional logic and predicate logic, the form of logic discovered by Aristotle.

The categorical is primarily the evaluation of arguments consisting of syllogisms of three catagorical statements, that is, sentences which begin with one of the quantifers "ALL", "SOME" or "NOT" and which seperate a subject term and a predicate term with a copula ("ARE" or "ARE NOT"). Through the use of Venn Diagrams or an ancient conceptual tool known as the square of opposition, the validity of any such syllogism can be derived from their form alone.