Re: Maudlin's Machine and the UDist

From: Hal Finney <hal.domain.name.hidden>
Date: Mon, 8 Aug 2005 09:42:06 -0700 (PDT)

I speculated:
> > I guess that you would say that if the unused
> > counterfactual machinery would actually work if tested, then she is
> > conscious; but if the counterfactual machines were broken or blocked
> > such that they wouldn't work (even though they are not used) then she
> > is unconscious. And perhaps you can say that the machines are in fact
> > tested in other branches of the multiverse, so the criterion is more
> > than merely a hypothetical difference between unused working machines
> > and unused broken machines. I see some difficulties with this position
> > but I better first hear whether this is what you have in mind before
> > trying to extrapolate further.

Russell replied:
> That is indeed my meaning. What difficulties do you see?

I see a few problems. The first is the concept that the multiverse
will contain copies of the machine that execute the counterfactuals.
While this could happen, it would normally be to a very, very tiny degree,
and it seems highly implausible that this could cause any actual effects.

In the case of Maudlin's thought experiment, the intention of the operator
is to run the machine on the specific inputs that it is pre-programmed
to handle. In effect, it is doing a replay of a previously computed
calculation. The counterfactual machinery is not intended to be
activated. All of the effort and skill of the operator will be devoted
to pre-setting the machine into the precise state necessary for an
exact replay, as Maudlin describes in detail.

Your interpretation depends on there being worlds in the multiverse
where these circumstances do not hold. But the only way such a world
could exist is if the operator somehow fails to achieve his goal.
The measure of such worlds, if the operator is skillful and effective,
will be extremely tiny. Only in worlds where the machine breaks or the
operator makes a mistake (or perhaps the operator's brain malfunctions
so he changes his mind about what to do) will the counterfactuals be
explored.

My problem is that such worlds are so few and so remote from the
great majority of worlds where the machine is operating as designed,
i.e. without triggering the counterfactual mechanisms, that it is hard
to see how the presence of consciousness could depend on activity
in those worlds. We might also note that those worlds are causally
disconnected from the one in question due to decoherence, and again
it seems questionable how a real phenomenon like consciousness can be
affected by what is happening in another universe.

Now, we would do an experiment which was designed to more effectively test
and exercise the machine in a mode where it would seem more plausible
to say that the multiverse was testing the counterfactuals. We could
in effect treat Olympia as a quantum computer, somehow initializing it
in a superposition of states, both the replay state and the many states
which would trigger counterfactuals, and then let it run like that.
In that case it would make more sense to say that the multiverse was
testing the counterfactuals and perhaps to say that the presence or
absence of consciousness was dependent on what happens across the
many worlds in this superposition. But that is not the usual case of
exercising Olympia. Instead, it is put, as certainly as we are able,
into a single initial state. If there do appear variations in the
multiverse it is unintentional, and such variations will be remote and
of small measure.

A related problem is that if we do consider the entirety of the
multiverse, undoubtedly there will be corners where virtually anything
happens. In a normal run of the Olympia machine augmented with the
counterfactuals, indeed if we look hard enough we can find corners of the
multiverse where the counterfactuals are explored, as just discussed.
Perhaps on this basis you want to say that the machine is conscious.
But what if we have blocked the counterfactual mechanism as Maudlin
described? You probably want to say that the machine is unconscious now.
Yet there are corners of the multiverse where the blockage fails and
the counterfactual mechanism continues to operate. Doesn't that mean
that in fact the machine should be conscious, after all?

In general, there will be all kinds of variations happening throughout
the multiverse. There will be worlds where the counterfactuals are
tested and they work, but also worlds where the counterfactuals are
tested and they fail (due to blockage or just plain broken machinery).
In yet other worlds the machine may fail or misbehave in any number of
bizarre ways. It could even implement a different calculation, perhaps
even a different consciousness, elsewhere in the multiverse.

My basic problem is that the multiverse is so big, and so much variation
is possible, that it will not work to say that consciousness depends on
activity that is spread across the multiverse. If you try to pin it down
so that it depends on what happens merely on a particular world and its
near neighbors, then that will not in general test the counterfactuals.
If you expand it to include a wide range of possibilities, then there
is too much going on, too many variations and bizarre outcomes, so
that the criteria you are trying to use for consiciousness are met in
some worlds and contradicted in others. All in all I don't think this
approach will work as a general method for making consciousness supervene
on physicality.

Hal Finney
Received on Mon Aug 08 2005 - 13:36:02 PDT