Monday, June 22, 2009

Stating the obvious

van Inwagen writes in Material Beings that his metaphysical thesis that there are no chairs is compatible with what the folk, speaking colloquially, say when they say there are chairs.

``This is because the ordinary man does not, in the normal course of events, say things like `There are tables'; rather, he says things like `Some of my tables are antiques.'" (from Tye's review)

Likewise, Vann McGee, an all-purpose defender of classical logic, notes (in conversation) that people never assert tautologies. In fact, he seems to hold something even stronger: ordinary language is compatible with classical logic even though it's the case that speakers are sometimes hesitant to assent to tautologies and even explicitly deny them. A case in point is speakers' hesitancy with LEM and Bivalence when confronted with vague borderline cases.

This is tough. By such lights speakers cannot even set up a prima facie presumption that

1. There are chairs.

or

2. I am neither thin nor not thin. (``She is and she isn't.")

At least with regards to van Inwagen, it certainly does seem fairer to be Lewis-like (PW) in conceding that one's theory ``disagrees extravagantly with commonsense notions of what there is." The dynamic is surely that people rarely say things that they find obvious. But this is not really a license to deny the obvious!

Then again: Tye makes the interesting, surely true, point in his review of van Inwagen that our everyday concepts like chair have no necessary and sufficient conditions of application. Does this mean that every reductive analysis is doomed to fail? This doesn't seem fair to reductive projects.

...``The result is that (2c) is not equivalent to (1). This result is not, I think, suprising: reductive paraphrases, like badly worn tires, tend to develop leaks in new places shortly after their old leaks are patched.
I am not, then, persuaded...where van Inwagen first goes wrong is in supposing, as many have before him, that it is possible to construct a reductive analysis of material object parthood. Our concepts generally do not have necessary and sufficient conditions. I see no reason to believe that this case is any different."



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