On 4/25/2017 1:59 AM, Bruno Marchal wrote:
On 25 Apr 2017, at 01:13, Bruce Kellett wrote:
On 24/04/2017 6:07 pm, Telmo Menezes wrote:
On Mon, Apr 24, 2017 at 6:08 AM, Russell Standish
<li...@hpcoders.com.au> wrote:
On Sun, Apr 23, 2017 at 11:49:51AM +0200, Telmo Menezes wrote:
Ok, so you are rejecting computationalism. Computationalism is the
hypothesis that our mind supervenes on computations (sorry Bruno,
it's
easier to write for the purpose of this discussion :). You are
declaring that mind supervene on the physical brain.
That is not it at all. We've clarified with Bruno many times that
computational supervenience is compatible with physical
supervenience. Which is just as well, as otherwise it would be so much
the worse for computationalism.
I have no doubt that the brain is a physical computer, and that
computations performed by the brain are no different from any other
computations.
We are discussing physicalism and computationalism, and if they are
compatible or not, correct?
Bruce repeatedly makes variation of the claim: "look, the brain is
physical and the brain generates consciousness, these are the facts".
This is what I am replying to. It's an argument from authority that
leaves no space for debate or reasoning.
First, it is not an argument from authority, it is an argument made
on the basis of all the available evidence -- consciousness
supervenes on the physical brain.
Second. An argument from authority is not necessarily a reason to
reject that argument. Because life is short and we cannot be experts
in absolutely everything, we frequently have to rely on authorities
-- people who are recognized experts in the relevant field. I am
confident that when I drive across this bridge it will not collapse
under the weight of my car because I trust the expertise of the
engineers who designed and constructed the bridge. In other words, I
rely on the relevant authorities for my conclusion that this bridge
is safe. An argument from authority is unsound only if the quoted
authorities are themselves not reliable -- they are not experts in
the relevant field, and/or their supposed qualifications are bogus.
There are many examples of this -- like relying on President Trump's
assessment of anthropogenic global warming, etc, etc.
Third, since it is now clear that the term "physicalism" refers to
the belief in primary matter, I have never ascribed to "physicalism".
Usually I use "Weak materialism" for the "assumption/belief" in
primary matter. primary means "in need to be assumed"; Something is
"primary" if to get its existence we need to assume it, or something
equivalent. For example, we know since the failure of logicism that
numbers are primary. We cannot derive them from logic.
But we can - and did - derive them from observation and manipulation of
objects. Numbers came from measuring the size of sheepherds, the steps
from one place to another,... You learned them that way at your
mother's knee.
Of course, we can derive them from the combinators theory, but
combinators are Turing equivalent to the numbers.
Weak materialism is just the belief in some matter, and that matter
cannot be explained by something non material.
I must used "weak" before materialist, because the term "materialist"
has a special meaning in philosophy of mind: it means that only matter
"really" exist, ad is opposed to dualism (matter and mind exists) and
immaterialism monism (only immaterial objects exist)
Physicalism is the assumption, in metaphysics/theology, that physics
is the fundamental science to which all other sciences can be, in
principle, reduced.
We can conceive some forms of physicalism which are immaterialist, for
example Tegmark is close to this. But usually, most physicalist are
weak materialist, and often I use weak materialism and physicalism as
being quasi the same thing.
I am an empirist, indeed, I extracted "computationalism" from biology,
well before I knew about Church and Turing. And I take physics very
seriously, and as the ultimate judge. Indeed, my point is that if
mechanism is correct, the physical reality is "in the machine's head",
and that is what makes mechanism testable: by comparing the physics in
the head of the machine with the physics inferred from the observation.
Testable requires not comparison, but falsifiability. So if
computationalism predicts things that are not observed, as it must if it
is to explain thoughts, then it seems it if falsified. It is saved only
by the too cheap trick of saying everything exists.
I do not know what "primary matter" is supposed to mean, and it
certainly has never been a subject of study that I have encountered
in my lifetime of work in physics.
The expression "primary matter" comes from Aristotle, which is the
first to clearly assume it as a metaphysical assumption/theory.
He used it because he was criticizing Democritus who had explicated the
idea of "atoms and the void". We only know of the atomist philosophy
indirectly. Criticism was congenial to the Roman Church, but the
original was not. If the atomist had prevailed instead of Aristotle and
Christianity, science would be 900yrs more advanced.
Brent
It has no role in physics at all, except helping the physicists to
sleep and not to be too much perturbate by the mind-body problem,
which since day one is the trouble maker for those who want to be
physicalist or weak-materialist.
What I have argued for is the existence of an external, objective,
physical world about which there is intersubjective agreement.
No problem with this, even if the "cosmos" (not the universal wave,
but the branch we are in) will appear eventually to be much plausibly
a first person plural construct (of numbers, not machine).
Whether the matter in this world is primary or emergent from
something more fundamental is an open question, and still the subject
of active debate in the physics community: I have no commitment to
either side of this argument. Likewise, there is an ongoing debate
among physicists about realist or anti-realist interpretations of
quantum mechanics, alongside more general debates about realism in
the philosophy of physics in general.
So I do not take kindly to attempts to silence me, or put me down, by
categorizing my views in simplistic terms, or in ways that I have
never entertained.
My problems with computationalism arise from the fact that I do not
believe in mathematical platonism,
I prefer to use "platonism" for Plato's theology, and use "realism"
here. I also do not believe in mathematical realism. But arithmetical
realism is needed by any one willing to give sense to the
Church-Turing thesis, or number theory. Arithmetical realism is
neutral on finitism/not-finitism. It is just the agreement with
Robinson arithmetic. It is even consistent with ultrafinitism. You can
believe in a biggest natural number. To be sure, the proof of the
consistency of RA + "there is a biggest natural number" cannot be done
by ultrafinitist means, but since Gödel we know that the proof of
consistency of a theory usually use more than the theory.
and the fact that computationalism has not produced any concrete
results about the physical world -- it is all speculative --
There is noting speculative in showing that physicalism is
incompatible with mechanism, and mechanism has been the motor of
basically all progress in science since Diderot (who defined
rationalism by Mechanism).
Usually, non-mechanism is judged speculative, as it speculates on
actual infinities (from personal god(s) to substantial soul) for which
we have no evidence at all.
Then mechanism reminds us that primary matter is also speculative.
So, most would agree that mechanism is the less speculative theory of
mind that we have. Indeed, it even shows that physicalism and weak
materialism are incoherent, and reminds us that indeed, there are
never been any evidences for it. It is just an extrapolation of our
local feeling, similar to extrapolate that the earth is flat from very
local measurement.
there is not even a proof of the existence of an acceptable physical
solution. When you have derived Newton's laws from computationalism,
then we might have something to talk about.
The goal is to progress on the mind-body problem, and expose the
metaphysical prejudice. Then, criticizing a metaphysics because it
does not give result in physics, is like criticizing physics because
it does not give a recipe for the pizza. Today, mechanism seem to be
the only theory which propose an explanation why the average universal
numbers develop some physical beliefs, and is the only one capable of
explaining the difference between quanta and qualia.
Bruno
Bruce
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