Abstract
Aristotle’s syllogism, developed in the Prior Analytics, constitutes the first formal system of deductive inference and remained the dominant logical paradigm for over two millennia. This paper critically examined the formal structure, metatheoretical properties, and philosophical presuppositions of Aristotelian syllogism, and evaluated its implications for contemporary formal logic. While 1IDEAS: Uniuyo Journal of Philosophy and Multi-Disciplinary Studies Vol. 2, No. 1, SEPTEMBER 2026 modern predicate logic after Frege and Russell exposed many serious limitations of Aristotle’s logic for mathematics and science, recent scholarship emphasizes that Aristotle shares with modern logicians a fundamental interest in metatheory: his aim was to study the properties of inferential systems themselves rather than merely present a collection of valid arguments. This study demonstrated that syllogism is sound, complete, and decidable within its domain of monadic predicates and four categorical forms: A(Every S is P), E (No S is P), I (Some S is P), and O (Some S is not P). Its limitations—lack of relational predicates, nested quantifiers, and singular terms—preclude its use as a foundation for mathematics, yet these same restrictions yield computational tractability. The paper argued that Aristotle’s syllogism is best understood not as a failed predicate logic but as a complete proof theory for a decidable fragment. Its contemporary implications are threefold: (1) it anticipates modern concerns with proof structure, consistency, and decision procedures; (2) it provides a historically grounded model for decidable term logics and description logics used in AI and ontology engineering; and (3) it challenges the assumption that expressive power is the sole metric of logical adequacy. Syllogism remains relevant as a case study in the tradeoff between expressivity and tractability.
Keywords: Aristotle, syllogism, proof theory, formal logic, term logic, metatheory, contemporary logic.
Author(s):
Idorenyin Francis Esikot, PhD
Professor of Philosophy
Department of Philosophy
Faculty of Arts
University of Uyo
Uyo – Nigeria
Idorenyinesikot@uniuyo.edu.ng
Darty Emmanuel Darty, PhD
Senior Lecturer
Department of Philosophy
Faculty of Arts
University of Uyo
Uyo – Nigeria
dartydarty@uniuyo.edu.ng
Idem Peter Udo
Department of Philosophy
Faculty of Arts
University of Uyo
Uyo – Nigeria
idempudo@gmail.com