Wolfgang Schwarz

Hi Wo,

Yes, this is why one should really run the conceivability argument with the conceivability of P&~Q (for the specific P that specifies the actual physical truths) as a premise, rather than the conceivability of "there are zombies". That's the way I always do it when formalizing the argument.

Hi! Right, that seems to block the loophole.

(The situation is a little confusing. I think a type-A materialist should concede that the consciousness role could turn out to be unrealized. If it does, P&~Q is true, and conceivable and possible. Yet if the consciousness role is realized, P&~Q is not even conceivable. So could a type-A materialist say that while it's conceivable that P&~Q is conceivable, in fact P&~Q probably isn't conceivable? That seems at least somewhat misleading, since there isn't really any single sentence or proposition 'P&~Q' whose conceivability is merely conceivable: if the consciousness role is unrealized and P&~Q conceivable, then P is a different sentence than if the consciousness role is realized and P&~Q inconceivable.)

Don't want to bug you, Dave, but I'm really curious how you'd answer the scrutability question I asked a while ago (while you were in Italy): is "there are planets" *verified* at zombie world?

Right, this is why one needs the truth of Q as an (explicit or tacit) premise, too. An eliminativist type-A materialist will say that P&~Q is actually true, so they can happily concede its conceivability and possibility.

On verification in zombie worlds:

From the claim that PQTI implies (apriori entails) all macrosopic truths, it doesn't follow that PTI implies no macroscopic truths. It could be e.g. that it implies spatial truths but not color truths, for example. But personally I'm inclined to think that Q plays a significant role in implying most macroscopic truths, even spatial truths, because of a response-dependent element in many or most macroscopic concepts. Taking the Rubber Ball World case, if told that there are entities with a certain microstructural composition at the actual world, but told nothing at all about how entities with this sort of composition (or any composition) typically look or feel, then I think we're not in a position to make any judgment about whether or not they're made of rubber. This means that the 1-intension of "There are rubber balls" isn't true at Rubber Ball world, but it doesn't mean that it's false there -- better to say that it's neither true nor false there. Something similar may well apply to the 1-intension of "there are planets" at zombie world, at least if we grant that appearances play an important reference-fixing role for "planets" (which I think is plausible though not 100% obvious).

Somehow that got posted twice -- sorry. One other point re your original post on scrutability: of course the terms with the partially response-dependent element that I mentioned will have distinct 1-intension and 2-intension. On my view this goes even for spatiotemporal terms. But if one denies this, then spatial terms won't be response-dependent and their 1-intensions will apply normally at zombie worlds. On my view the most basic terms with identical 1-intension and 2-intension are mental terms, causal/nomic terms, and logical/mathematical/categorical terms, plus terms grounded in some fashion in these: so e.g. "friend", "philosopher", "action" plausibly have identical 1- and 2-intensions. Of course most of those won't apply at a zombie world if that world lacks mentality (setting aside issues about whether consciousness is required for mentality). So the main terms whose 1-intensions will apply to the zombie world just as they do to our world are causal/nomic/logical/mathematical/categorical terms (plus spatiotemporal terms if you think those go in too), and those grounded in these.

Thanks!

Does the conceivability of zombies threaten type-A materialism, the claim that all mental truths are a priori entailed by the physical truths? Can we imagine beings exactly like us in all physical respects, but lacking consciousness? If so,...