Definition
The history of logic traces how the study of valid inference evolved over roughly two and a half millennia — from its birth in ancient Greece, through medieval refinement, to the explosive formalisation of the modern era. It is the story of a discipline that was twice thought finished and twice transformed.
Graham Priest uses this history to make a key point: logic is not a fixed body of eternal truths handed down once and for all. It is an inquiry that has repeatedly revised its own foundations as new kinds of reasoning came into view.
Why it matters
How it works
Greek logic had two strands: Aristotle's theory of the syllogism, dealing with quantified class statements, and the Stoics' logic of whole propositions joined by connectives. Medieval thinkers preserved, taught, and elaborated this inheritance, treating syllogistic logic as nearly complete.
The decisive break came with George Boole, who treated logic algebraically, and Gottlob Frege, who introduced a powerful logic of quantifiers and relations capable of underpinning mathematics itself. Priest stresses that the story did not end there: the twentieth century produced relevance logics, modal logics, and many-valued logics, each challenging the classical consensus and keeping the subject alive.