Given that it’s been over a year since we’ve had any posts, I’ve decided to try to jumpstart the blog again. Here goes…
While reading Sider’s Writing the Book of the World, I noticed a strange dialectic circularity. One of Sider’s main theses is that structure is objective: it’s ‘out there in the world’ in some metaphysically heavy sense. But, Sider then goes on to give an account of objectivity in terms of structure. Given this circularity, it’s possible to find a reductio.
Sider claims that structure is not subjective (i.e. structure is objective). I take this to mean that sentences about structure are not subjective. Without loss of generality, let’s take the following sentence about structure:
(S): ‘being negatively charged’ is structural
Sider wants to claim:
(O): (S) is not subjective
He goes on to give the following account of subjectivity: “A sentence is subjective…if and only if it’s truth-value depends on which of a range of equally joint carving candidates is meant by some term in the sentence, where the candidate that we in fact mean was selected in a way that is not arbitrary, but reflects something important about us, such as our values” (59). Combining this account of subjectivity with (O) gives us:
(O’): It’s not the case that the truth value of (S) depends on which of a range of equally joint carving candidates is meant by some term in (S), where the candidate that we in fact mean was selected in a way that is not arbitrary, but reflects something important about us, such as our values.
This roughly amounts to saying that in order for facts about structure to be objective, they must ‘carve at the joints’ — in other words, facts about structure must themselves be structural. But that’s a condition that far too easy to meet. For instance, take a simple expressivist view of structure. Roughly, to say ”being negatively charged’ is structural’ is simply to express some mental attitude A towards ‘being negatively charged’. I think we can all agree that, pretheoretically, this is a subjective account of structure. But, if Sider’s account of subjectivity is correct, an expressivist account of structure is consistent with the claim that (S) is objective. Accepting (O’) amounts to expressing attitude A towards ‘is structural'; this is all we need to accept (O’), because the terms in (S) do not have ‘a range of equally joint carving candidates’ — by our own lights, ‘structural’ is joint-carving. So, either Sider must reject his account of objectivity or accept that expressivism about structure is consistent with structure being objective. I take it that he will choose the former.