Terence Parsons presents a new study of the development and continuing value of medieval logic, which expanded Aristotle's basic principles of logic in important ways. Parsons argues that the resulting system is as rich as contemporary first-order symbolic logic.

I. SUPPOSITION AND SIGNIFICATIONIn an insightful article on the medieval theory of supposition, Elizabeth Karger noted a remarkable development in the characterization of the material mode of supposition between William of Ockham and his contemporaries in the early fourteenth century and Paul of Venice and others at the turn of the fifteenth century.1. E. Karger, “La Supposition Materielle comme Supposition Significative: Paul de Venise, Paul de Pergula,” in A. Maierú, ed., English Logic in Italy in the 14th and 15th Centuries (...) (Naples, 1982), pp. 331–41. For William, material supposition is explicitly ‘non-significative’, while for Paul, every mode of supposition is a kind of signification.2. Paul of Venice, Logica Magna (Tractatus de Suppositionibus), ed. and trans. A. Perreiah (St. Bonaventure, 1971), p. 4: “nam omnis suppositio est significatio.” In particular, we can set these definitions in opposition. (shrink)

Buridan’s theory of sentences with epistemic verbs (‘to know’, ‘to believe’, etc.) has received much attention in recent scholarship. Its originality with respect to Ockham’s approach, however, has been importantly overestimated. The present paper argues that both doctrines share crucial features and basically belong to the same family. This is done by comparing Buridan’s notion of the ‘appellation of reason’ with Ockham’s application to epistemic sentences of the general principle that a predicate always ‘appellates its form’.

v. 1. On the twelfth century theories of fallacy.--v. 2. The origin and early development of the theory of supposition.