The doctrine of semantic granularity can, I think, shed considerable light on the meaning and motivation of relativism about truth. It may even help resolve debates surrounding it.
In this post I will try to briefly indicate how I think this is so. I had a post on granularity and the paradox of analysis lined up for this month, but I will postpone it and get this one out now, in response to this related post on the blog language goes on holiday.
This may not be very clear to others yet, although I think I have it fairly clear in my own mind. Reading the other posts on granularity here, including future ones, will certainly help. (Soon I will do a granularity "roundup" post, collecting them all in one place and sumarizing their contents, but for now see the bottom of this post.) I will try my best under present constraints, in the hope that some reader gets something clear out of this.
Why bother? Well, I think this may be a pretty powerful and important application of granularity, since relativism about truth is such a vexed and widely ramified issue in our intellectual culture. Anyway, here goes.
Granularity and Relativism about Truth
Once the doctrine of granularity is on the table in its basic form, questions of this sort arise (among others): OK, meanings and the like can be carved up at different granularities, but what is the range of possible carvings up?
Surely there are limits; it is far from being the case that, for every two instances of thought or talk, there is a granularity at which they are counted as meaning the same. And it seems quite probable, although this is more debatable, that it also isn't the case that, for every two instances of thought or talk, there is a granularity at which they are counted as differing in meaning.
And do these different possible carvings up fall on a continuum, or are there multiple dimensions of what may count and what may not count towards difference in meaning? (I think the answer is that there are multiple dimensions, and I will try to say something about this in future.)
Now, these sorts of questions suggest a basic constraint on possible or "admissible" granularities for carving up propositions: if two instances of propositions are to be counted as meaning the same, they had better not differ in truth-value.
And now we can see relativism about truth in a new light, namely as the rejection of this constraint.
Furthermore, it is not hard to see how, in certain areas, it may be tempting to reject the constraint. Between two instances, there may be so much of the sort of stuff which usually counts toward sameness of meaning in common that it is really tempting to count them - at some granularity - as meaning the same, while nevertheless certain other important stuff differs so as to make (it best to say that) the truth-values come out differently in the two instances.
This may be particularly likely to happen with the rich and complicated concepts in the moral and aesthetic domains. And perhaps others too. And so we get a new perspective on the motivation of relativism about truth as well.
Of course, in many areas this sort of thing just won't happen - the motivation won't be there. It has often been observed (most saliently in my memory by my former teacher Adrian Heathcote, in unpublished writings) that relativism about truth appeals to people in some domains, such as morality and aesthetics, where it would never seem appealing in others. And so the general, woolly-seeming doctrine that all truth is relative can be and often is condemned as being based on a far too narrow diet of examples: you may be tempted to say such a thing after considering some moral or aesthetic matter (for instance), but with other matters such as basic geography or facts about how many chairs there are in some easily observable room, the notion that something may be true for me, while something else is true for you, would never occur to anyone, and seems completely absurd.
But relativism about truth need not be maintained that way - it may be maintained that in some areas, or with some propositions, truth is relative. Call this moderate relativism.
And, as I have tried to indicate, granularity considerations can shed some light on what this may mean, and what may motivate it. This in itself is, I think, a good advertisement for the power of granularity considerations, as relativism about truth is a big deal, especially in the borderlands of philosophy.
OK, good. But now a further question comes up: is it true? Are there, in some areas or with some kinds of propositions, admissible granularities on which two instances of propositions get counted as meaning the same but differing in truth-value?
I think that here we need to consider allowing the possibility of a kind of pluralism - slightly different sets of concepts such that, on one set, the issue gets decided one way, and on another set, the issue gets decided the other way. For instance, it could be that the maintainer of moderate relativism has a slightly broader or more flexible notion of meaning/proposition than the denier. And perhaps realizing that may enable them to resolve their dispute.
Still, it may give way to different disputes about how best to use certain words, and about which concepts to deploy where - but these may be more tractable.
(Here we get into the difficult and important topic of verbal disputes. Chalmers has recently had things to say on this topic, which was arguably being neglected before he did so. See his paper 'Verbal Disputes'.)
So, granularity considerations can be fruitfully applied to relativism about truth. They may help to (i) clarify its meaning, (ii) shed light on what motivates its adoption and (iii) help show the way to a resolution of debates over it.
Kripke's Puzzle and Semantic Granularity
Facts and Granularity
Granularity and Quine
Metaphysical Realism and Conceptual Relativity: An Application of Granularity