Wednesday, October 31, 2012

Deflationist view of the role of the truth predicate

To: Shan A.
From: Geoffrey Klempner
Subject: Deflationist view of the role of the truth predicate
Date: 24 October 2008 11:22

Dear Shan,

Thank you for your email of 22 October resending the University of London essay which you originally emailed on 19 October, in response to the Logic question, 'Deflationists claim that the predicate 'true' does not stand for any property. What do they claim is the role for this predicate, and can this claim be justified?'

Coincidentally, I responded to the very same essay two days ago. My student, however, took a different line entirely, concentrating on whether the role deflationists generally attribute to the truth predicate can be justified in the face of alternative views about the nature and importance of truth.

There are two alternative ways of reading the question: (a) What according to deflationists is the role for the truth predicate and how good are their arguments for saying that it has that role? (b) What according to deflationists is the role for the truth predicate? Is that the only possible role for truth, or are there other roles which they have not considered?

You have given a very good, well researched answer to version (a). As a rule, I don't look at the examiners' reports, so I am genuinely uncertain what they are looking for in this question. As far as I can see, a good answer to the question might be an answer to (a), or (b), or both.

It is worth noting that asking about the 'role' of a particular predicate or concept, is a comparatively recent development in analytic philosophy. If you picked up a text book from 30 years ago, all you would read about are purported 'definitions' or 'analyses' of truth, where a definition of truth is a formula which gives necessary and sufficient conditions for the statement, ''P' is true,' or for the statement, 'It is true that P.' Talking about 'roles' rather than definitions gives the philosopher a certain amount of latitude.

You mention objections raised to the substitutional and objectual interpretations of propositional quantification, e.g. (P)(Percy asserts that P -> P), or (EP)(Percy asserts that P & P). (Incidentally, the latter would be a better reading of 'What Percy says is true' in a normal context of discourse. It is rare that we say, of a particular individual, that *everything* they say is true.)

However, the problems with substitutional or objectual readings isn't just a picky point. It could be argued that quantifying over propositions is absurd, it doesn't make any sense at all. That is because propositions aren't 'things'. The prosentential theory works well enough on the surface of language (you emphasize that the question is one of 'deep structure') but it can't be used to derive a strict definition of truth in terms of necessary and sufficient conditions.

On the other hand, if the question is not one of deriving a strict definition but merely 'illuminating the role' of truth, then different considerations can be brought to bear.

On the deflationist side, it can be said that the introduction of the truth predicate significantly increases the representational power of a language. A term that is merely 'redundant' has no effect on the representational power of language. It is a piece of discardable baroque. You don't want the term to be too easily definable, for that would be the same as showing that we didn't need the term in the first place.

My sympathies are with the deflationists. Yet I think that there is a danger of missing an important point. Dummett argues in his seminal article 'Truth' (reprinted in 'Truth and Other Enigmas') that an essential aspect of the concept of truth is that we 'aim at making true statements'. This seems on the face of it rather trite, but it is in fact a profound observation. To ask about the 'point of truth' is to raise a fundamental logical and metaphysical question about what it is to 'consider a statement' or 'make an assertion' in the first place. What is judging, or stating or asserting? The debate between the realist and the anti-realist, which so intrigues Dummett, is a debate about the nature of truth which (as I would argue, though Dummett would not) is consistent with a deflationary stance yet at the same time demonstrates the depth of the questions that the philosopher is able to raise, once armed with the truth predicate.

In other words, it is philosophers who need the term 'truth', more than anyone else. Outside philosophy, we rarely use the immense power of generalization that the truth predicate embodies to its fullest extent.

That is how, paradoxically, one can state that the question of the 'nature of truth' is relatively trivial -- a matter of simply giving the equivalence formula -- while at the very same time, one of the deepest questions in philosophy.

All the best,

Geoffrey