Definition:Aristotelian Logic

Aristotelian logic is a system of logic which is based upon the philosophy of Aristotle. It forms the cornerstone of the entirety of "classical" logic.

It was Aristotle who, in particular, introducted the two principles:


 * Principium tertii exclusi, the Principle of the Excluded Third (PET), otherwise known as principium tertium non datur, the Principle (or Law) of the Excluded Middle (LEM). This states that for all statements, the statement is either true or it is not. In the language of symbolic logic: p \lor \lnot p.


 * Principium contradictionis, the Principle of Non-Contradiction (PNC). This states that a statement can not be both true and not true at the same time. In the language of symbolic logic: $$\lnot \left({p \land \lnot p}\right)$$.

A logical system which includes both of these principles is known as Aristotelian logic.