On 17 Jan 2014, at 01:28, Stathis Papaioannou wrote:
On 16 January 2014 23:08, Bruno Marchal <[email protected]> wrote:
On 16 Jan 2014, at 09:11, Stathis Papaioannou wrote:
On 16 January 2014 16:26, Jason Resch <[email protected]> wrote:
The computational metaphor in the sense of the brain works like
the Intel
CPU inside the box on your desk is clearly misleading, but the
sense that
a
computer can in theory do everything your brain can do is almost
certainly
correct. It is not that the brain is like a computer, but rather,
that a
computer can be like almost anything, including your brain or
body, or
entire planet and all the people on it.
Jason
I think neuroscientists have, over decades, used the computational
metaphor in too literal a way. It is obviously not true that the
brain
is a digital computer, just as it is not true that the weather is a
digital computer. But a digital computer can simulate the
behaviour of
any physical process in the universe (if physics is computable),
including the behaviour of weather or the human brain. That means
that, at least, it would be possible to make a philosophical zombie
using a computer. The only way to avoid this conclusion would be if
physics, and specifically the physics in the brain, is not
computable.
Pointing out where the non-computable physics is in the brain rarely
figures on the agenda of the anti-computationalists. And even if
there
is non-computational physics in the brain, that invalidates
computationalism, but not its superset, functionalism.
OK. But in a non standard sense of functionalism, as in the
philosophy of
mind, functionalism is used for a subset of computationalism.
Functionalism
is computationalism with some (unclear) susbtitution level in mind
(usually
the neurons).
Now, I would like to see a precise definition of "your"
functionalism. If
you take *all* functions, it becomes trivially true, I think. But any
restriction on the accepted functions, can perhaps lead to some
interesting
thesis. For example, the functions computable with this or that
oracles, the
continuous functions, etc.
Briefly, computationalism is the idea that you could replace the brain
with a Turing machine and you would preserve the mind.
OK.
This would not
be possible if there is non-computable physics in the brain, as for
example Penrose proposes.
You mean, relevant for the brain processes which make my consciousness
relatively manifestable to you. OK.
(comp will imply that the material stuff the brain is *apparently*
made of is not entirely computable, but comp is neutral on the
question if the brain exploits such "non computability" (that would
lead to a comp-quantum computations)).
But in that case, you could replace the
brain with whatever other type of device is needed, such as a
hypercomputer, and still preserve the mind. I would say that is
consistent with functionalism but not computationalism.
OK. That's what I call indeed weakening of computationalism.
mathematically, that changes nothing, it only levels up the problem
from the arithmetical to what is the called the hyperarithmetical.
(coincidence, as it is not the same hyper than hypercomputation (which
is more general)).
The idea that
replicating the function of the brain by whatever means would not
preserve the mind, i.e. would result in a philosophical zombie, is
inconsistent with functionalism.
It is a bit fuzzy, because the expression "function of the brain" is
not well defined. "function" is a very general notion. If the function
of my brain is to incarnate me, then functionalism is trivial. If the
function of my brain is "teaching logic" then I survive if you
substitute my brain with the brain of any logicians (who likes to
teach).
I see what you mean, and weak-comp gives examples of such
functionalism,. Yet, it seems to me that taking all functions tends to
triviality or fuzziness. I think.
Bruno
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Stathis Papaioannou
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