Re: Quantum spookiness in the brain?

On 9 Apr, 19:51, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On Wed, 9 Apr 2008 16:30:42 +0000 (UTC), Paul J Gans <g...@xxxxxxxxx>
wrote:

<snip>



I believe that Penrose was dealing with what I will call
the "mechanistic view" of the mind. In that view two absolutely
identical brains will think absolutely the same thoughts and make
absolutely the same decisions.

Folks who think this are basically saying that there can be no
free will since thoughts are then totally dependent on the physical
details of the brain that thinks them.

For many, the only way out of this is to posit a supernatural
something that would allow absolutely identical brains to think
different thoughts.

Penrose, I believe, was pointing out that it is impossible to
have absolutely identical brains because of quantum uncertainty.

The rest of his thinking then took off from this point of departure.
And I agree that the rest of his thinking may be just so much
poop, but the problem of identical brains is a real one and I believe
it is solved by quantum uncertanty.

The notion that identical brains must think alike and act alike is,
indeed, logically equivalent to the notion that, given the details of
one brain, one can then compute presumably the future of what it will
do.

This assumes that the physical laws are computable, or at least can be
approximated by computable functions to any arbitrary level of
precision.
This is exactly the assumption that Penrose and Hameroff challenge.

All known fundamental physical phenomena seem to be described by
(approximately) computable laws, with the only exception of quantum
wavefunction collapse, which seems to be probabilistic.
Many interpretations of quantum mechanics have been formulated to try
to address this oddness. Some just accept it as it is while others
suggest that it might be actually a deterministic chaotic phenomenon.

Penrose and Hameroff instead suggest an interpretation where quantum
wavefunction collapse is governed by a (still unknown) uncomputable
physical law.

Their rationale for doing so is that they have convinced themselves
that certain aspects of human behavior (like mathematical intuition)
aren't compatible with a computable (and possibly probabilistic)
physics, thus they have cringed on the only not completely explained
fundamental phenomenon.

However, their argument for the non-computability of human behavior is
flawed (IMHO and in the opinion of most experts), making their
proposed interpretation unparsimonious.

<snip>

.

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