The success of syllogistic has been such that many of the features originally characterizing this logic have changed over decades. The present study aims at offering a faithful, possibly comprehensive, account of Aristotle’s deductive logic, by extending the inherently proof-theoretical approach introduced by von Plato in 2009/16. Concretely, the main novelty consists in treating syllogistic as a natural deduction system of rules and ‘perfecting’ arguments (for imperfect moods) as derivability proofs in tree form. Nothing is added to the original source but, in this way, assertoric and apodictic syllogistic are transparently reconstructed and Aristotle’s perfecting proofs are proved to be always correct. This would also be a first step to make the whole modal fragment fully comprehensible and to rehabilitate syllogistic as a fertile theory in the context of natural language reasoning.

Peer reviewed