RE: computationalism and supervenience

From: Stathis Papaioannou <>
Date: Wed, 30 Aug 2006 21:04:30 +1000

Peter Jones writes:

> > I'm not necessarily talking about every possible computation being implemented by
> > every physical system, just (at least) the subset of finite computations implemented by
> > a physical computer or brain. I think this is another way of saying that a recording, or
> > a single trace of a computation branching in the multiverse, can be conscious. To prevent
> > a recording being consious yoiu can insist on counterfactual behaviour, but that seems an
> > ad hoc requirement introduced simply to prevent the "trivial" case of a recording or any
> > physical system implementing a computation.
> The requirement that computations require counterfactuals isn't
> ad hoc, it comes from the observation that computer programmes
> include if-then statements.
> The idea that everyting is conscious unless there is a good
> reason it isn't -- *that* is ad hoc!

No, it follows from the idea that anything can be a computation. I think this is trivially obvious,
like saying any string of apparently random characters is a translation of any English sentence
of similar or shorter length, and if you have the correct dictionary, you can find out what that
English sentence is. This is analogous to finding an alien computer which, when power is applied,
is set into motion like an inscrutable Rube Goldberg machine. If you get your hands on the
computer manual, you might be able to decipher the machine's activity as calculating pi. Moreover,
you might be able to reach inside and shift a few gears or discharge a few capacitors and make it
calculate e instead, utilising the fact that the laws of physics determine that if the inputs change,
the outputs will change (which, I trust you will agree, is the actual physical basis of the if-then

Now, in human languages as in machine design, there are certain regularities to make things
easier for user. It might be possible, albeit difficult, to decipher a foreign language or figure out
what an alien computer is computing by looking for these regularities. However, it is not necessary
that there be any pattern at all: the characters in the unknown language may change in meaning
every time they appear in the string in accordance with a random number generator, a cryptographic
method called a "one-time pad". Similarly, the meaning of the physical states of the alien computer
could change with each clock cycle according to some random number sequence, so that if you had
the key you could figure out that the computer was calculating pi, but if you did not its activity would
seem random. I don't think it would be reasonable to say that the computer is only calculating pi when
you have the manual at hand ready to refer to, even though without the manual the computer is
completely useless to you if you want to calculate the area of a circle, for example.

Remember, even the apparently random computer handles counterfactuals, in that if a gear or a
semiconductor junction were changed, the whole subsequent activity of the machine would change,
and the manual would tell you how the computation had changed.

You could dismiss the computations of random physical systems as trivial or useless, but what if you
believe that some computations can be conscious? It would be no easier for us to observe or interact
with these computations than it would be for us to observe or use the pi calculation, but by
definition the conscious computations *themselves* would be self-aware.

We might say in the above cases that the burden of the computation shifts from the physical activity
of the computer to the information in the manual. The significance of this is that the manual is static,
and need not even be instantiated if we don't care about interacting with the computer: it is a
mathematical object residing in Platonia.

Stathis Papaioannou
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Received on Wed Aug 30 2006 - 07:06:21 PDT

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