Re: computationalism and supervenience

From: Hal Finney <>
Date: Wed, 6 Sep 2006 13:44:35 -0700 (PDT)

Russell Standish writes:
> Why do you say this? Surely physical supervenience is simply
> supervenience on some physical object. Physical objects are spread
> across the multiverse, and are capable of reacting to all
> counterfactuals presented to it.
> Inside views are local - but the whole shebang must be spread across
> the Multiverse.

I suppose it depends on your definitions. As I suggested, supervenience
in a single world model means that consciousness depends on local physical
activity, and not on causally unconnected events. In a multiverse,
actions in parallel worlds are causally unconnected to actions here.
It seems rather odd to say that the supervenience thesis says that
whether my computer is conscious depends on what is happening in some
remote parallel universe.

I also think there are problems with this notion that objects are spread
across the multiverse, and in particular that all counterfactuals
are tested. It's not clear to me that we can unambiguously define
the counterpart to this particular object in an arbitrary multiverse.
For very "near" or "similar" multiverses it may seem unproblematic,
while for extremely "far" or "different" multiverses there will obviously
be no counterparts. There would probably be a gray area in the middle
in which an object was related to one in our universe but perhaps not
exactly the same.

This exposes a difficulty with the notion that all counterfactuals are
tested. In the first place, many thought experiments aim to refrain from
testing counterfactuals - Maudlin's is of this nature. Something has
to go seriously wrong with Maudlin's scenario for counterfactuals to
be tested. In the second place, many counterfactuals may be bizarre
and unlikely, so that the circumstances under which they are tested may
require extremely strange events. These situations would suggest that
such counterfactuals will only be tested in relatively remote parts of
the multiverse, parts quite different from our own. And then we have
to ask, is it really the "same" machine that is being tested?

And by "same" here, I think we mean more than just "designed the same"
or "isomorphic" - we mean that it has some kind of shared identity,
that in some sense this *is* the machine we see in our universe, just
exposed to different inputs. Given the problems I mentioned with this
notion of identity across the multiverse, it's not clear that this
concept makes sense.

Hal Finney

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Received on Wed Sep 06 2006 - 16:48:26 PDT

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