Friday, June 7, 2013

Does 'is true' specify a genuine property?

To: Bogdan P.
From: Geoffrey Klempner
Subject: Does 'is true' specify a genuine property?
Date: 12th March 2010 12:46

Dear Bogdan,

Thank you for your email of 6 March with your essay for the University of London BA Logic module, in response to the question, 'Does the predicate 'is true' specify a genuine property of assertions?'

I agree with you that this is a difficult topic, but you seem to have a good handle on it. I think possibly that your investigation has been handicapped to some extent by your assumption that a deflationist theory of truth somehow downgrades the importance of truth, or has the implication, as you put it, that 'the truth predicate has a very limited role to play in communication'. Yet you start your essay with a statement with which anyone would agree: 'The notion of truth plays a major role in our lives and is fundamental to communication and scientific investigation'!

No wonder you feel a bit confused.

You cover many of the points that need to be made in an answer to this question. For a start, we may ask what it means to say that 'is true' does or does not 'specify a genuine property'. You go about answering this in the right way, by looking at other predicates which do specify genuine properties. For example, 'is intelligible'. If I say that John's assertion was intelligible, you who do not find it intelligible can ask me to justify my claim, and I will do so by explaining what John said. After I have given my explanation, you do find the statement intelligible. Other statements, though they pass tests for grammaticality (i.e. being formally acceptable), are really not intelligible. There is no possibility of giving an explanation in this case, because there is nothing to explain. There is surely a strong case for saying that intelligibility is a property which an assertion can have, or lack, even though there may be many cases (as with other properties) where there is room for dispute.

It doesn't follow from this that intelligibility is something that can be defined, other than in a piecemeal way. However, the question was about ‘being a genuine property’ not about definability.

It is useful to think of some other examples: 'John's assertion was combative', 'John's assertion was candid', 'John's assertion was poetic'.

Why isn't truth like this? Consider an example. Suppose I say, 'Theories of truth have an innate tendency to supervene on theories of perception.' I just made this up, as an example of a statement which is unintelligible, although this is not something that just anyone would see immediately. For a start, I don't know what it means for a theory to 'supervene' on another theory, or how a theory can have a 'innate tendency'. By contrast, if you ask me what it is for this statement to be true, then I don't have to say anything more than, 'Theories of truth have an innate tendency to supervene on theories of perception' is true if and only if theories of truth have an innate tendency to supervene on theories of perception.

One way of explaining the ambitions of non-minimalist theories of truth (correspondence, which you mention, but also coherence and pragmatic) is that they attempt to give an explanation which is analogous to the explanation we gave of intelligibility. In the example above (which I won't repeat again) you tell some story about words, the world, the actions of human beings etc. etc. and the upshot of this story is an explanation which somehow accounts for the attribution of the truth predicate.

Theorists of truth are quick to point out that a statement of what truth is, or what truth consists in, is not the same as a criterion of truth. Knowing what is the true theory of truth doesn't give you any additional means of verifying an assertion which you didn't have before. What it does give is an understanding of what you are saying when you state that an assertion is true.

I am fully with Davidson on this. If you understand the statement then you know what it is for it to be true, because that's just what understanding is. There is nothing more to say. If you do try to say something more, you are risking an infinite regress. Frege made substantially the same point in his essay, 'The Thought: a Logical Inquiry' where he expressly argues for the indefinability of truth on the grounds that we would need to ask, of any putative definition, whether it is 'true'.

However, having got this far, I don't think that it necessarily follows that philosophers have 'nothing further to say' about truth. On the contrary, there are real, substantive issues about truth, such as the question of realism vs. anti-realism about truth (see Dummett 'Reality of the Past'), or the question whether ethical assertions, which formally can be described as 'true' of false (because they pass the grammatical test) are capable of being true, and, if so, how do we account for the difference between ethical and non-ethical assertions without falling back on a more full blooded account (e.g. as a correspondence theorist would say, 'Ethical assertions do not correspond or fail to correspond with facts').

For this reason, I find it intelligible to say that while truth is not a genuine property and is not definable, nevertheless there is scope for a non-trivial theory *about* truth.

All the best,

Geoffrey