Ockham’s Logic

John F. Sowa

Before Peirce and Tarski, the most detailed development of the model-theoretic approach was by William of Ockham. Peirce had studied Ockham’s Summa Logicae in depth, he owned a copy of the first printed edition (1488), and he had delivered a lecture on Ockham’s logic at Harvard in 1869. Unfortunately, Coffa (1991) was unaware of the contributions by Ockham and Peirce when he wrote his history of semantics. To see the continuity, compare the following quotations from Ockham, Bolzano, Peirce, and Tarski:

In addition to the quantifiers and Boolean operators, Ockham also analyzed truth conditions for tenses and plurals. (Page numbers refer to the translation by Fredoso and Schuurman.)


Ockham, William of (1323) Summa Logicae, Paris: Johannes Higman, 1488; the edition owned by C. S. Peirce. Also volume 1 of Opera Philosophica, ed. by P. Boehner, G. Gál, & S. Brown, St. Bonaventure, NY: Franciscan Institute, 1974.

Ockham, William of (T) Ockham’s Theory of Terms, translated by Paul Vincent Spade.

Ockham, William of (T) Ockham’s Theory of Terms, translation of Part I of Ockham (1323) by M. J. Loux, University of Notre Dame Press, Notre Dame, IN, 1974.

Ockham, William of (P) Ockham’s Theory of Propositions, translation of Part II of Ockham (1323) by A. J. Freddoso & H. Schuurman, Notre Dame, IN: University of Notre Dame Press, 1980.

Ockham, William of (W) Philosophical Writings, ed. and translated by Philotheus Boehner, revised by S. F. Brown, Hackett Publishing Co., Indianapolis. Includes Latin and English selections from Ockham (1323) and other works.

Spade, Paul Vincent, Writings about and translations of medieval logic and philosophy.

For other references see the combined bibliography for this web site.