Medieval logicians often characterized their discipline by saying that it aims at providing efficient means to distinguish truth from falsity. Thus propositions, as truth-bearers, are items logicians spent a great deal of time and energy describing and analysing. More precisely, propositions were studied “bottom-up”, i.e. as complexes of terms (subject, predicate, copula), but also “top-down”, i.e. as premises and conclusions in arguments (syllogisms). When studied for themselves or as such, however, propositions give rise to three main questions: (i) What is a proposition? (ii) What does a proposition signify? (iii) How is propositional truth to be accounted for? This chapter considers medieval answers to those questions. After having expounded and discussed the different opinions and arguments put forward by logicians roughly between the eleventh and the fifteenth centuries, the chapter tackles the question of the relation between some tenets of medieval semantics of the proposition and the modern notions of facts and states of affairs.

WHAT IS A PROPOSITION?

Before even approaching how medieval logicians defined propositions, the very first thing to stress is the difference between the medieval and the contemporary meaning of the technical term ‘proposition’. A propositio – that is, a proposition in the medieval sense of the word – is a type of sentence, i.e. a linguistic expression (a string of words, possibly a single word) singled out by its truth-evaluable character: a proposition is that kind of sentence about which it makes sense to ask is it true or false? A proposition in the contemporary sense of the word, by contrast, is not a linguistic expression. Rather, it is what is meant by a truth-evaluable linguistic expression (or the content of the corresponding act of judging). Accordingly, in its contemporary sense, a proposition is neither a string of words, nor a mental entity, but something abstract with a distinctive Platonist flavour. Unless otherwise specified, this chapter uses the term ‘proposition’ in the medieval sense. How are propositions and judgements (or acts of judging) related? A judgement is a complex mental act of composing (for affirmative judgements) and dividing (for negative ones), i.e. the so-called second operation of the intellect, distinguished from simple apprehension (= first operation) on the one hand, and argumentation (= third operation) on the other.