First published Tue Jun 13, 2006; substantive revision Tue Jan 22, 2013
Truth is one of the central subjects in philosophy. It is also one of the largest. Truth has been a topic of discussion in its own right for thousands of years. Moreover, a huge variety of issues in philosophy relate to truth, either by relying on theses about truth, or implying theses about truth.
It would be impossible to survey all there is to say about truth in any coherent way. Instead, this essay will concentrate on the main themes in the study of truth in the contemporary philosophical literature. It will attempt to survey the key problems and theories of current interest, and show how they relate to one-another. A number of other entries investigate many of these topics in greater depth. Generally, discussion of the principal arguments is left to them. The goal of this essay is only to provide an overview of the current Theories. Many of the papers mentioned in this essay can be found in the anthologies edited by Blackburn and Simmons (1999) and Lynch (2001b). There are also a number of book-length surveys of the topics discussed here, including Burgess and Burgess (2011), Kirkham (1992), and Künne (2003).
The problem of truth is in a way easy to state: what truths are, and what (if anything) makes them true. But this simple statement masks a great deal of controversy. Whether there is a metaphysical problem of truth at all, and if there is, what kind of theory might address it, are all standing issues in the theory of truth. We will see a number of distinct ways of answering these questions.
1. The neo-classical theories of truth
Much of the contemporary literature on truth takes as its starting point some ideas which were prominent in the early part of the 20th century. There were a number of views of truth under discussion at that time, the most significant for the contemporary literature being the correspondence, coherence, and pragmatist theories of truth.
These theories all attempt to directly answer the nature question. what is the nature of truth? They take this question at face value: there are truths, and the question to be answered concerns their nature. In answering this question, each theory makes the notion of truth part of a more thoroughgoing metaphysics or epistemology. Explaining the nature of truth becomes an application of some metaphysical system, and truth inherits significant metaphysical presuppositions along the way.
The goal of this section is to characterize the ideas of the correspondence, coherence and pragmatist theories which animate the contemporary debate. In some cases, the received forms of these theories depart from the views that were actually defended in the early 20th century. We thus dub them the ‘neo-classical theories’. Where appropriate, we pause to indicate how the neo-classical theories emerge from their ‘classical’ roots in the early 20th century.
1.1 The correspondence theory
Perhaps the most important of the neo-classical theories for the contemporary literature is the correspondence theory. Ideas that sound strikingly like a correspondence theory are no doubt very old. They might well be found in Aristotle or Aquinas. When we turn to the late 19th and early 20th centuries where we pick up the story of the neo-classical theories of truth, it is clear that ideas about correspondence were central to the discussions of the time. In spite of their importance, however, it is strikingly difficult to find an accurate citation in the early 20th century for the received neo-classical view. Furthermore, the way the correspondence theory actually emerged will provide some valuable reference points for the contemporary debate. For these reasons, we dwell on the origins of the correspondence theory in the late 19th and early 20th centuries at greater length than those of the other neo-classical views, before turning to its contemporary neo-classical form.
1.1.1 The origins of the correspondence theory
The basic idea of the correspondence theory is that what we believe or say is true if it corresponds to the way things actually are—to the facts. This idea can be seen in various forms throughout the history of philosophy. Its modern history starts with the beginnings of analytic philosophy at the turn of the 20th century, particularly in the work of G. E. Moore and Bertrand Russell.
Let us pick up the thread of this story in the years between 1898 and about 1910. These years are marked by Moore and Russell's rejection of idealism. Yet at this point, they do not hold a correspondence theory of truth. Indeed Moore (1899) sees the correspondence theory as a source of idealism, and rejects it. Russell follows Moore in this regard. (For discussion of Moore's early critique of idealism, where he rejects the correspondence theory of truth, see Baldwin (1991). Hylton (1990) provides an extensive discussion of Russell in the context of British idealism.)
In this period, Moore and Russell hold a version of the identity theory of truth. They say comparatively little about it, but it is stated briefly in Moore (1899; 1902) and Russell (1904). According to the identity theory, a true proposition is identical to a fact. Specifically, in Moore and Russell's hands, the theory begins with propositions, understood as the objects of beliefs and other propositional attitudes. Propositions are what are believed, and give the contents of beliefs. They are also, according to this theory, the primary bearers of truth. When a proposition is true, it is identical to a fact, and a belief in that proposition is correct. (Related ideas about the identity theory and idealism are discussed by McDowell (1994) and further developed by Hornsby (2001).)
The identity theory Moore and Russell espoused takes truth to be a property of propositions. Furthermore, taking up an idea familiar to readers of Moore, the property of truth is a simple unanalyzable property. Facts are understood as simply those propositions which are true. There are true propositions and false ones, and facts just are true propositions. There is thus no “difference between truth and the reality to which it is supposed to correspond” (Moore, 1902, p. 21). (For further discussion of the identity theory of truth, see Baldwin (1991), Candlish (1999),
Cartwright (1987), Dodd (2000), and the entry on the identity theory of truth .)
Moore and Russell came to reject the identity theory of truth in favor of a correspondence theory, sometime around 1910 (as we see in Moore, 1953, which reports lectures he gave in 1910–1911, and Russell, 1910b). They do so because they came to reject the existence of propositions. Why? Among reasons, they came to doubt that there could be any such things as false propositions, and then concluded that there are no such things as propositions at all.
Why did Moore and Russell find false propositions problematic? A full answer to this question is a point of scholarship that would take us too far afield. (Moore himself lamented that he could not “put the objection in a clear and convincing way” (1953, p. 263), but see Cartwright (1987) and David (2001) for careful and clear exploration of the arguments.) But very roughly, the identification of facts with true propositions left them unable to see what a false proposition could be other than something which is just like a fact, though false. If such things existed, we would have fact-like things in the world, which Moore and Russell now see as enough to make false propositions count as true. Hence, they cannot exist, and so there are no false propositions. As Russell (1956, p. 223) later says, propositions seem to be at best “curious shadowy things” in addition to facts.
As Cartwright (1987) reminds us, it is useful to think of this argument in the context of Russell's slightly earlier views about propositions. As we see clearly in Russell (1903), for instance, he takes propositions to have constituents. But they are not mere collections of constituents, but a ‘unity’ which brings the constituents together. (We thus confront the ‘problem of the unity of the proposition’.) But what, we might ask, would be the ‘unity’ of a proposition that Samuel Ramey sings—with constituents Ramey and singing—except Ramey bearing the property of singing? If that is what the unity consists in, then we seem to have nothing other than the fact that Ramey sings. But then we could not have genuine false propositions without having false facts.
As Cartwright also reminds us, there is some reason to doubt the cogency of this sort of argument. But let us put the assessment of the arguments aside, and continue the story. From the rejection of propositions a correspondence theory emerges. The primary bearers of truth are no longer propositions, but beliefs themselves. In a slogan:
A belief is true if and only if it corresponds to a fact.
Views like this are held by Moore (1953) and Russell (1910b; 1912). Of course, to understand such a theory, we need to understand the crucial relation of correspondence, as well as the notion of a fact to which a belief corresponds. We now turn to these questions. In doing so, we will leave the history, and present a somewhat more modern reconstruction of a correspondence theory.
1.1.2 The neo-classical correspondence theory
The correspondence theory of truth is at its core an ontological thesis: a belief is true if there exists an appropriate entity—a fact—to which it corresponds. If there is no such entity, the belief is false.
Facts, for the neo-classical correspondence theory, are entities in their own right. Facts are generally taken to be composed of particulars and properties and relations or universals, at least. The neo-classical correspondence theory thus only makes sense within the setting of a metaphysics that includes such facts. Hence, it is no accident that as Moore and Russell turn away from the identity theory of truth, the metaphysics of facts takes on a much more significant role in their views. This perhaps becomes most vivid in the later Russell (1956, p. 182), where the existence of facts is the “first truism.” (The influence of Wittgenstein's ideas to appear in the Tractatus (1922) on Russell in this period was strong, and indeed, the Tractatus remains one of the important sources for the neo-classical correspondence theory. For more recent extensive discussions of facts, see Armstrong (1997) and Neale (2001).)
Consider, for example, the belief that Ramey sings. Let us grant that this belief is true. In what does its truth consist, according to the correspondence theory? It consists in there being a fact in the world, built from the individual Ramey, and the property of singing. Let us denote this <Ramey. Singing >. This fact exists. In contrast, the world (we presume) contains no fact <Ramey. Dancing >. The belief that Ramey sings stands in the relation of correspondence to the fact <Ramey. Singing >, and so the belief is true.
What is the relation of correspondence? One of the standing objections to the classical correspondence theory is that a fully adequate explanation of correspondence proves elusive. But for a simple belief, like that Ramey sings, we can observe that the structure of the fact <Ramey. Singing > matches the subject-predicate form of the that -clause which reports the belief, and may well match the structure of the belief itself.
So far, we have very much the kind of view that Moore and Russell would have found congenial. But the modern form of the correspondence theory seeks to round out the explanation of correspondence by appeal to propositions. Indeed, it is common to base a correspondence theory of truth upon the notion of a structured proposition. Propositions are again cast as the contents of beliefs and assertions, and propositions have structure which at least roughly corresponds to the structure of sentences. At least, for simple beliefs like that Ramey sings, the proposition has the same subject predicate structure as the sentence. (Proponents of structured propositions, such as Kaplan (1989), often look to Russell (1903) for inspiration, and find unconvincing Russell's reasons for rejecting them.)
With facts and structured propositions in hand, an attempt may be made to explain the relation of correspondence. Correspondence holds between a proposition and a fact when the proposition and fact have the same structure, and the same constituents at each structural position. When they correspond, the proposition and fact thus mirror each-other. In our simple example, we might have: