Avicenna’s logics with sentence-type terms: 1. Wholly muttaṣil syllogisms

We study an early and neglected logical work of Avicenna from around the years AD 990–1000, known as Short Epitome in Logic. In this work Avicenna introduces a new form of hypothetical logic, based on the categorical syllogisms of Aristotle but with terms that are sentences rather than nouns. His reading of the sentences of this logic anticipates the ‘adverbs of quantification’ of David Lewis, and the design of the new logic is close to that of George Boole’s ‘theory of Secondary Propositions’.