Truth, Theories of

This entry surveys five influential medieval theories of truth, paying particular attention to the bearers of truth within each theory as well as to their emphasis, whether metaphysical or semantic. (1) Anselm’s notion of truth is characterized by the concept of rectitude: something is true if it is/does what it ought to be/do, that is, if it conforms to God’s design for it (2) Abelard’s theory of truth revolves around the notion of the dicta of propositions, i.e., what is said by propositions. Dicta are the actual truth-bearers for Abelard. (3) Thomas Aquinas defends an approach to truth based on the notion of adequation of intellect and object. The fit can occur in both directions: an object can conform to the concept of it in its creator’s intellect, and a concept can conform to the object insofar as it represents it accurately in the knower’s intellect. (4) Theories of truth based on the concept of supposition provide recursive definitions of the truth of propositions based on the supposition of their terms, and reject any metaphysical import concerning the notion of truth. (5) Theories of truth emerging from fourteenth century treatises on insolubilia start out with a fundamentally Aristotelian definition of a true proposition as a proposition signifying as things are, which is then modified so as to introduce quantification over the signification of a proposition. The notion of truth was of crucial importance for medieval philosophers, as could be expected given their keen interest in logic and semantics, on the one hand, and in metaphysics and philosophical theology on the other. (Naturally, there is a strong medieval tradition dealing with a biblical notion of truth. Here, however, we will focus on philosophically inclined theories of truth, even though the line between theology and philosophy is a very thin one in the medieval context.) But to attain an accurate understanding of medieval theories of truth, it is important to realize that the class of such theories is more heterogeneous than the class formed by modern theories of truth. For example, we philosophers of the early twenty-first century (in particular those working within the analytic tradition) are accustomed to viewing truth essentially as an attribute of complex linguistic entities. Now, when examining medieval theories of truth, the modern philosopher may be surprised by the wide variety of entities that can receive the attribute “true” – truth-bearers for short: propositions (in the Latin sense of propositio, i.e., roughly what is now known as a declarative sentence, a statement, but which can be spoken, written, or mental), as to be expected, but also objects, mental judgments, actions, and even God. A general characteristic of these theories (in fact, of medieval logical theories in general) is the influential position occupied by the Aristotelian corpus, in particular discussions from the Categories and De interpretatione (in first instance) and the Metaphysics (which only became widely read halfway the thirteenth century, see Dod 1982). Also influential was the neoplatonic-Augustinian conception of truth which equated truth to being: “The true is that which is” (Augustine, Soliloquia II, 5, quoted in Aertsen 1992:160). These two radically different sources of inspiration may explain the heterogeneity of medieval theories of truth, which will be illustrated here by the analysis of five representative medieval approaches to truth. To help us understand the different theories in their diversity, a few distinctions may come in handy. First, among the different medieval theories, one encounters two basic kinds of entities to which truth is attributed – two kinds of truth-bearers: linguistic and mental entities, and objects in extra-mental reality. Indeed, the attribution of truth to objects is one of the distinctive features of some medieval theories of truth (known as objectual (Künne 2003:3.1.2) or ontological (Wippel 1989:295) truth in the literature). But all medieval theories recognize spoken, written, and mental propositions and judgments as bearers of truth as well (known as propositional (Künne 2003:3.1.2) or logical (Wippel 1989:295) truth in the literature). Secondly, let us distinguish between metaphysical and semantic approaches to truth, a distinction pertaining to emphasis. The metaphysical approach is characterized by the focus upon the properties and states of things that make truth-bearers true. By contrast, the semantic approach is characterized by minimal or no focus on what must obtain in reality for an entity to be deemed true; rather, semantic theories of truth concentrate on properties of the linguistic entity in question, in particular its signification or the supposition of its terms, in order to determine its truth-value. In other words, what makes a proposition true within the semantic approach are primarily properties of the proposition itself, and not the state of things in reality. Notice that one should not conflate the metaphysical approach with correspondence theories of truth, which are characterized by the idea that truth is a relational property involving a relation (often of likeness) of a given entity to some portion of reality. Indeed, there are semantic theories of truth that are also fundamentally based on correspondence. To illustrate the difference between metaphysical and semantic approaches, consider two correspondentist definitions of the truth of propositions: 1. A proposition is true iff things are as it signifies them to be. 2. A proposition is true iff it signifies things to be as they are. In (1), the truth of a proposition depends on properties of things, and its signification is, as it were, taken for granted (it is not under scrutiny); therefore, (1) characterizes a metaphysical approach to truth. By contrast, in (2) the truth of a proposition depends on a feature of the proposition itself, its signification, and the state of things is in turn taken for granted; (2) is thus a semantic definition of truth. But, to be sure, not all medieval theories of truth are based on correspondence; those articulated on the basis of the notion of supposition, for example, are not. In the latter case, truth is not a relational property but rather a monadic property of truth-bearers. Notice also that, with respect to the first distinction, a semantic theory of truth will only have linguistic entities as its truth-bearers. A metaphysical theory of truth may recognize nonlinguistic as well as linguistic entities as its truth-bearers; but a theory of truth whose truth-bearers are exclusively propositions, but which focuses on what must obtain in reality for propositions to be true and not on their semantic properties is also, according to this distinction, a metaphysical theory of truth (in what follows, I do not treat such theories, but one could find examples thereof among fourteenth-century realists such as Walter Burley and John Wycliff; see Cesalli (2007)). It is not the nature of truth-bearers that makes a theory semantic or metaphysical, but rather the nature of their causes of truth, i.e., whether semantic or metaphysical facts