Monday, April 4, 2011

Truth conditional semantics of vague predicates

To: Joao T.
From: Geoffrey Klempner
Subject: Truth-conditional semantics of vague predicates
Date: 3 November 2011 13:50

Dear Joao,

Thank you for your e-mail of 14 October, with your essay for units 13-15 of the Philosophy of Language program, "Is it possible to give a coherent truth-conditional account of the semantics of vague predicates?"

Once again, I have to apologise for not responding sooner. In fact, I read your essay more than a week ago but I am ashamed to say I could not make any progress with it because I could not remember what I had said in the program and didn't have the units with me! (I was on a train at the time, with my palm top computer: a perfect opportunity to work.) It must be age creeping up on me.

I don't have a weekly radio program, at least not yet. I am on the list of 'friends' of Radio Sheffield who get invited at regular intervals (every few months) to talk about my work, or comment on the week's news. Radio Sheffield is a local rather than a national station. On BBC Radio 4, there are philosophy programs and philosophy debates from time to time. But four hours seems a very long time. I doubt whether that could happen now.

Getting back to your essay, even now, when I have re-read the relevant material (unit 13) I am still struggling to understand. One thought that helps to 'position' the things that you say is the relation between views in the philosophy of language and the traditional clash between correspondence, coherence and pragmatist theories of truth. There is a clear link between the correspondence (or 'metaphysical') theory and realism. While the anti-realist theory involves elements from both the coherence and pragmatist theories.

Where I disagree with the traditional theories of truth is over the question whether truth can be 'defined'. I would argue that defining the predicate "is true" as the predicate of disquotation ("Snow is white" is true if and only if snow is white) rules out the possibility of any more substantial definition. The reason is the one that Frege gave (at the beginning of his essay 'The Thought: A Logical Inquiry"). If a philosopher defines truth as the condition XYZ, then we can still conceive of the possibility that a given statement P, which is XYZ, is false and not true.

The account which I offer of truth as an 'imaginary target' or a 'fiction' is intended as a contribution to the theory of meaning. The ideal of convergence which the notion of truth represents plays a role in linguistic practice to the extent that we are aware that there is a reason for striving to keep our judgements 'in line' with one another. The world is not chaotic. The world is not designed to frustrate our attempts to get to know it, but on the contrary, rewards the inquirer who perseveres in his inquiry. The more we seek to align our judgements with the world, the more we will agree with one another - at least, in the long run.

Thus, in the case of vagueness, we recognize that some persons might be better judges than others about 'what to say' in a particular borderline case. Not always, however. It would be strange to imagine that there could be persons who had a special talent for judging whether or not a particular individual could correctly be described as 'bald'. Perhaps I did not stress enough in the program that linguistic practice is often inconsistent. Words change their meanings over time, or depending on where one lives or one's social class, and there is no accurate way to track those changes.

The point you seem to be making is that statements are not made in isolation. You say, "If the acceptance of a statement 'as true' licenses the assertion of certain other statements to the truth status, despite of its vagueness, that will be hardly difficult to refute the bearing idea of an increasing verisimilar world made of these vague statements...".

Now, there is a danger here of succumbing to a kind of linguistic idealism, that sees the "verisimilar world" which we make up out of the judgements we accept as true as the world *itself*. But this would involve, in effect, defining truth as coherence, whereas I have already argued that truth cannot be defined by such a notion. A coherent set of statements can still be false. Similarly, a statement that 'works' (pragmatism) can still be false, even though the belief that it is true is more beneficial than the belief that it is false. And so on.

We don't just sit back and make statements. We probe the world, conduct experiments, engage in research. The idea that guides this activity is that we are in 'pursuit of truth'. This is a valid idea, insofar as it is an intrinsic part of linguistic practice to see our words as aiming beyond discourse to the world. However, truth characterized in these terms is only an 'ideal target' or 'fictional target'.

You don't mention in your essay the various attempts that have been made to provide an analysis of the truth-conditions for vague statements (for example, using many-valued logic which I talk about in unit 13). The point that I am arguing for is that once we accept the idea of truth as an 'imaginary target', we can hold onto the thought that a vague statement aims at truth, without needing to give a reductive analysis of exactly which set of conditions makes a given vague statement true, or false.

All the best,