Marchal Thesis

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Date: Mon, 10 May 1999 22:39:56 -0700

Bruno Marchal's paper,
Computation, Physis and Cognition

English translation 1st draft


The computationalist hypothesis, or more simply,
*mechanism*, which I consider here, is the
hypothesis according to which *I* am a machine or
*you* are a machine. The precise way in which I
am interested in the hypothesis that we can
survive, not just with an artificial heart or kidney,
etc., but also with an artificial digital brain (finitely
describable) assuming it is suitably configured at
an adequate level.
The aim is not to defend this hypothesis but to
examine the consequences, notably concerning
the mind-body problem.
In particular I shall show, contrary to a very
widespread belief, among philosophers and
doctors as much as the layman, that mechanism is
incompatible with materialism.
I will demonstrate that mechanism is incompatible
with materialist monism, which claims that is only
one universe, which can in principle be described
entirely in terms of physics. On the way I will
demonstrate that mchanism is also incompatible
with dualism, which holds that there is
simultaneously a tangible world (described by
physics) and a mental world.
Hence I will show that mechanism necessitates a
monist idealism incompatible with any form of
materialism. This proof will not resolve the mind-
body problem, but will lead towards a new
formulation of the question. Essentially, with the
computationalist hypothesis, the mind-body
problem is transformed in the research deriving:
1. a phenomenology of mind - capable of
explaining the origin and nature of knowledge and
belief; and
2. a phenomenology of matter, capable of
explaining the origin and nature of our
observations and our theories of physics.
The first point can hardly be considered original.
With computationalism, psychology is, *in
principle*, trivially reduced to information theory.
The originality is in the demonstration that to
resolve the body-mind problem, one is obliged to
derive the phenomenology of matter from the
phenomenology of mind. That is, physics is *in
principle* a branch of psychology.
This is precisely the reverse of our usual attempts
to reduce or try to understand psychological
phenomena from the substrate of the brain -
physical, or even cosmic or universal.
On the contrary, mechanism demands a
psychology which eliminates all materialist
ontology rather than a materialism which
eliminates mental ontology.
Mechanism therefore requires us to consider
physics as a branch of psychology, itself a branch
of information theory, which is in turn a branch of
number theory. The word, "branch" is used here in
a slightly more general sense than normal; this will
be clarified during the course of the proof.
An attentive logician will note that matter is not
*logically* eliminated. But he would fail at any
attempt to explain physical sensations through
physical science alone.
There is a certain irony in this situation.
Mechanism is generally invoked by reductionist
materialists to debunk the spirit and to counter
dualism and other spiritualism. And it works in
practice, but on closer examination (as proposed
here), the dematerialisation does not stop with the
spirit but extends to the body, matter and the
This work is not speculative. It stands up well to
demonstration or hypothetico-deductive argument:
IF mechanism is true THEN physics *must* be
derived from psychology. I clarify this point in
Chapter 2.

Note on methodology
To help the reader keep track of the proof, I
decided to be as brief as possible. The poof, which
starts in Chapter 3, finishes by the end of Chapter
4. It does not assume any specific knowledge,
except a familiarity with Church's Thesis and, of
course, a smattering of high-school classical
philosopy (good treatments are given in Huisman
and Vergez, 1996 or Nagel, 1987). Appendix D
provides an introduction to the mind-body problem
as well as some supplementry definitions on the
concept of sufficient conditions for mechanism.
Chapter 1, which defines the hypotheses of the
*entire* work, raises some technical points which
are not ued in the proof. This additional material
will be used before Chapter 5.
Chapter 5 examines the search for a solution to
the mind-body problem in the light of the proof
given here. Unlike the proof, this research has a
few prerequisite techniques. You may consult the
technical report (Marchal, 1995) or the appendices
of this paper, or certain works such as Boolos,
1995, Webb, 1980, as well as Albert, 1992 and
Maudlin, 1994 on physics.
Received on Mon May 10 1999 - 22:39:57 PDT

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