Page 221 - Encyclopedia of Philosophy of Language

is taken to verify a proposition should indicate the possession of that property. Therefore a tempting alternative to the correspondence theory—an alter- native which eschews obscure, metaphysical concepts and which explains quite straightforwardly why ver- ifiability implies truth—is simply to identify truth with verifiability (Peirce 1932). This idea can take on vari- ous forms. One version involves the further assump- tion that verification is holistic—namely, that a belief is justified (i.e., verified) when it is part of an entire system of beliefs that are consistent and harmonize with one another (Bradley 1914; Hempel 1935; Blan- shard 1939). This is known as the coherence theory of truth. Another version involves the assumption that there is, associated with each proposition, some spec- ific procedure for finding out whether one should believe it or not. On this account, to say that a prop- osition is true is to say that it would be verified by the appropriate procedure (Dummett 1978; Putnam 1981). In the context of mathematics, this amounts to the identification of truth with provability.
The attractions of the verificationist account of truth are that it is refreshingly clear compared with the correspondence theory, and that it succeeds in connecting truth with verification. The trouble is that the bond which it postulates between these notions is implausibly strong. We do indeed take verification to indicate truth. But also we recognize the possibility that a proposition may be false even though there is perfectly good reason to believe it, and that a prop- osition may be true even though we are unable to discover that it is. Verifiability and truth are no doubt highly correlated; but they do not appear to be the same thing.
A third well-known account of truth is known as pragmatism (James 1909; Dewey 1938; Rorty 1982; Papineau 1987). As mentioned above, the veri- ficationist selects a prominent property of truth and considers it to be the essence of truth. Similarly, the pragmatist focuses on another important charac- teristic—namely, that true beliefs are a good basis for action—and takes this to be the very nature of truth. True assumptions are said to be, by definition, those which provoke actions with desirable results. Again, this is an account with a single attractive explanatory feature. But again the central objection is that the relationship which it postulates between truth and its alleged analysis—in this case, utility—is implausibly close. Granted, true beliefs tend to foster success; but it can easily happen that an action based on true beliefs leads to disaster, and that, by a stroke of good luck, a false assumption produces wonderful results.
2. Deflationary Theories
One of the few uncontroversial facts about truth is that the proposition that snow is white is true if and
only if snow is white, the proposition that lying is wrong is true if and only if lying is wrong, and so on. Traditional theories acknowledge this fact but regard it as insufficient and, as described above, inflate it with some further principle of the form 'X is true if and only if X has property P' (such as, corresponding to reality, verifiability, or being suitable as a basis for action), which is supposed to specify what truth is. A radical alternative to the traditional theories results from denying the need for any such further specification and taking the theory of truth to be nothing more than all equivalences of the form 'The proposition that p is true if and only if p' (Ramsey 1927; Wittgenstein 1953; Leeds 1978; Hor- wich 1990).
This proposal is best presented in conjunction with an account of the raison d'etre of the notion of truth: namely, that it enables us to express attitudes towards those propositions we can designate but not explicitly formulate. Suppose, for example, you are told that Einstein's last words expressed a claim about physics, an area in which you think he was very reliable. Sup- pose that, unknown to you, his claim was the prop- osition that quantum mechanics is wrong. What conclusion can you draw? Exactly which proposition becomes the appropriate object of your belief? Surely not that quantum mechanics is wrong, because you are not aware that that is what he said. What is needed is a proposition, K, with the following properties: that from K and any further premise of the form 'Einstein's claim was the proposition that p' you can infer 'p,' whatever it is. Now suppose that, as the deflationist claims, our understanding of the truth predicate con- sists in the stipulation that any instance of the fol- lowing schema, 'The proposition that p is true if and only if p,' must be accepted. Then your problem is solved. For if K is the proposition 'Einstein's claim is true,' it will have precisely the inferential power that is needed. From it and 'Einstein's claim is the prop- osition that quantum mechanics is wrong,' you can infer 'The proposition that quantum mechanics is wrong is true,' which, given the relevant axiom of the deflationary theory, allows you to derive 'Quantum mechanics is wrong.' Thus one point in favor of the deflationary theory is that it squares with a plausible story about the function of our notion of truth: its axioms explain that function without the need for any further analysis of 'what truth is.'
Not all variants of deflationism have this virtue. According to the redundancy/performativetheory of truth, the following pair of sentences, The prop- osition that p is true' and plain 'p,' have exactly the same meaning and express the same statement as one another; so it is a syntactic illusion to think that 'is true' attributes any sort of property to a proposition (Ayer 1935; Strawson 1950). But in that case it becomes hard to explain why we are entitled to infer 'The proposition that p is true' from 'Einstein's claim
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