ABSTRACT
This chapter introduces some of the main themes in medieval discussions of modal logic. It provides a high-level overview of a number of different aspects of the medieval discussions around modal logic before focusing on one specific account of modal logic, that of John Buridan, and its relationship to Aristotle’s modal logic. The chapter discusses three accounts of the modal operators that can be found in medieval texts: a temporal interpretation of modal expressions, an essentialist interpretation of modal expressions, and a possibility-as-alternative account of modal expressions. Syntactically, modal propositions can be obtained by adding a modal expression to an assertoric proposition. This can be done in two ways. The first way is to allow for the copula to be modified by a modal adverb. The other way to obtain modal propositions is to allow for one of the terms in a proposition to be a modal expression.
