Summa logicae

Introduction

Ockham wrote this textbook of logic in Latin around 1323, shortly before he was summoned to Avignon. It has three parts: on terms, on propositions and on arguments, the last covering syllogisms, demonstration, topics and fallacies. Its core is the theory of supposition, which describes what a term stands for in a sentence: an individual thing, a concept or the word itself. On this basis Ockham argues that universals are signs – concepts in the mind, which he understands as a kind of mental language – and not things outside it. The work became one of the most widely used logic books of the late Middle Ages.

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Connections

Builds on

• Organonc. 350 BCE · Aristotle

Criticizes

• Ordinatioc. 1300 · John Duns Scotus