LizR wrote:
On 11 June 2015 at 12:20, Bruce Kellett <bhkell...@optusnet.com.au
LizR wrote:
I suspect that "physics is not computable" is the /end/ result
of Brnuo's argument (comp2) - which is supposed to be a
/reductio/ on the notion of comp1. So comp1 assumes that physics
is computable, and that assumption leads to the result that it
isn't. Which is taken as an argument against physical
supervenience of consciousness on brains, although it could
equally be an argument against brains performing computations.
If that is the line of reasoning, then it would help if it were made
more explicit. I expect that the reason that it is not more explicit
is that it is actually incoherent. If comp1 leads to the conclusion
that comp1 is false, then comp1 is inconsistent. Not just false,
*inconsistent*. And as Brent is fond of saying, /ex falso
quodlibet/. Or better, /ex contradictione sequitur quodlibet/.
I think it is made explicit. Bruno has often claimed that his argument
is a /reductio/ on the physical supervenience thesis,
It seemed to me that the argument was directed against the notion of
primitive physicalism, rather than just the supervenience thesis. I do
not remember Bruno explicitly denying supervenience. It would be strange
if he did, since brain replacement by a computer at the appropriate
substitution level is the beginning of the argument.
But, as I have argued, the argument against primitive physicalism fails
because nothing is introduced that actually depends on primitive
physicalism. That is why the whole enterprise appears to backfire.
assuming I've got
that right. He is trying to show that the assumptions of comp1 lead to a
contradiction (and one of the assumptions of comp1 is that consciousness
supervenes on brains).
But there are other assumptions. Showing a contradiction only shows that
your starting point is inconsistent (assuming that all the other stages
of the reasoning are correct). It doesn't point to *which* assumption is
at fault. That comes down to metaphysics, so it is all irrelevant for
understanding the real world of experience.
Bruce
"You don't like my metaphsysics? That's all right -- I have a whole draw
full of alternative metaphysics available..."
** With apologies to Groucho Marx.
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