UCMA is making a claim about all minds, P1 is making a claim about some undefined subset of all minds.
They both talk about "all minds," but only one of them makes a claim -about- all minds.
A parallel pair of arguments might be:
All squares are rectangles
The claim that all squares are rectangles is unlikely to be true of all squares.
The first claim is stronger than the second, and requires more proof. The fact that we can in fact prove it is irrelevant, and part of why I chose this example; consider the inverse propositions that all rectangles are squares, and that that claim is unlikely to be true, to see why this is important.
The claim that all squares are rectangles is unlikely to be true of all squares.
This is analogous to the conclusion of the above argument, not P1. An analogue to P1 would have to be something like 'Any argument of the form 'for all squares s:(X)s is unlikely to be true.' The question would then be this: does this analogue of P1 count as an argument of the form 's:(X)s'? That is, does it quantify over all squares?
You might think it doesn't, since it just talks about arguments. But my point isn't quite that it must count as such an argument, but rather th... (read more)
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