Monday, April 23, 2007

Against Truth-Value Gaps?

I’ve been reading Michael Glanzberg’s ‘Against Truth-Value Gaps’ (link to penultimate version, page references to the published version). I found a lot of interesting stuff there, with much of which I agree—inter alia, that the point of assertion is to convey information, and that thus one should assert something in a context only if that would be (true and thus) true or false, in that that context.

As to the main point, however, I’m not sure I got it. I had my worry at the very first pages, and it was not mitigated in the subsequent fortysomething, so I guess there is probably something very basic I am missing. Any help appreciated.

The main claim of the paper is that

that there are no substantial truth-value gaps. There are some phenomena that appear like gaps, but they are importantly different. There are faux gaps, as I shall call them, but no substantial gaps. In particular, attention to the role of context dependence, and the ways in which utterances of meaningful sentences can fail to express propositions in some contexts, provides a rich theoretical basis for explaining away apparently substantial truth-value gaps as merely faux gaps. (p. 152)

A substantial gap occurs, or would have occurred, when something that is apt to be true or false—including utterances, interpreted sentences paired with context, and propositions—fails to be either. (p.151)

I am a bit uneasy with talk of propositions in this context: too many (subtly but crucially different) things might be meant, so that one has always to make explicit which one one is interested in—which might be held to make the usefulness of the notion at best debatable.

But never mind that, here is the worry: any “faux” gap seems to be a substantial gap, in the envisaged sense. Take a “faux” gap case, where an utterance of a meaningful sentence “fails to express a proposition” in a given context. Thus the utterance or, better, the (interpreted) sentence at the context fails to be true or false. As, admittedly, these are things apt to be true or false—unlike shoes and ships and sealing wax—, this would be (also) a substantial gap.


Aidan said...

Hey Dan,

Look at page 154. The thesis that there are substantial gaps is there taken to be the thesis that we need two sets to model the contents of assertions, which are taken to be propositions; the set of worlds where a given proposition is true and the set of worlds where it is false (since, given gaps, the former does not determine the latter).

It looks like Glanzberg is committing to the view that meaningful utterances that do not express propositions aren't truth-apt. I'll need to read the paper properly to see if that's really the view, but that's what 154 suggests to me. But we should note this isn't inconsistent with what he says on p151 - he doesn't commit, as you seem to suggest he does, to the view that utterances and other non-propositional things need be truth-apt. He just says these are '[c]ommon candidates'.

Dan López de Sa said...

Hey Aidan!

I think you might well be right: maybe he is after all committed to that view. But then the introductory remark at p. 151 would seem at least misleading, for even if strictly speaking compatible with such a commitment, as you point out, it strongly suggests a kind of neutrality as to what exactly are the things that—unlike shoes and ships and sealing wax—are apt to be true or false.

Moreover, such a neutrality seems indeed appropriate, given the dialectical purposes of the paper. For what about natural ways of implementing the view of vagueness as semantic indecision that have it that an utterance of a meaningful borderline sentence “fails to express a proposition” in a given context? Are we going to say that such a view is not committed to substantial gaps?