[FOM] The Lucas-Penrose Thesis
Muller F.A.
F.A.Muller at phys.uu.nl
Wed Sep 27 02:01:22 EDT 2006
Dear all,
I have two brief questions, which I shall
pose shortly, after the following introductory
sentences.
In 1961 the Oxford philosopher J.R. Lucas
argued, roughly put (I know), that minds
cannot be (modelled as) machines due to Godel's
Incompleteness Theorem. He repeated it,
with some replies to criticisms, in his
book *The Freedom of the Will* (1970).
[Lucas has a personal website with more
criticisms and responses, some of which
are incontestably witty.]
Among others, Hofstaedter discusses the
'Lucas Thesis' in his celebrated *Godel,
Esher, Bach* (1980).
The thesis became famous when Roger Penrose
propounded it in his best-seller *The
Emperor's New Mind*. Hence the often used
terminology `The Lucas-Penrose Thesis'.
In a follow-up, *The Shadows of the Mind*,
Penrose responds to critics. Rumour has it
that he only responds to friendly criticisms,
which leave the core of the cherished thesis
in tact, while he ignores devastating
criticisms, or only mentions them in order
to ignore them.
I don't know. In Uppsala, Sweden, 1992
(International Congress for Logic, Methodology
and Philosoph of Science)
I witnessed a discussion between Penrose
and D.C. Dennett on the Thesis; Dennett
was critical but not really convincing. Penrose
did not give an inch and seemed entirely
undisturbed by anything critical that was
brought up, by Dennett and others. I have heard
(or read), on another occasion, Penrose making
fun of the situation that everybody disagrees
with him but the critics also disagree
among themselves about what is wrong with
the argument.
It doesn't seem that some simply
fallacy is committed that once pointed
out, ends the story.
This reminds me of Einstein. The majority
of the responses to his most cited paper,
co-authored with Podolsky and Rosen on the
(alleged) incompleteness of quantum mechanics
(1935), was critical, but Einstein wrote in a
letter that all his critics disagree what exactly
was wrong with his argument. There has been
published a number of formalisations of the
EPR-argument, all transcending the bounds of
1st-order classical logical, either by adding
all sorts of ad hoc deduction-rules or by moving
to some modal logic. Some conclude that the EPR-
argument is invalid, others that it is (or
can be made) valid. Valid or not, it
certainly is an interesting and influential
argument.
Mutatis mutandis for the Lucas-Penrose
Thesis? I am not saying that the situation with
the Lucas-Penrose Thesis is wholly comparable.
I only report this association to awake
your interest. Here are my two brief questions.
1. Is there any subscriber on the FOM-list
who thinks the Lucas-Penrose Thesis is
true or plausible or can be made true or
plausible?
I have the impression that most informed
people think the thesis is false or
implausible or at least that its argument
is no good. Yet there a quite a few papers
published on the subject and they provide
different analyses.
2. Can someone recommend a paper where it
is established convincingly, once and
for all that the argument for the
Lucas-Penrose Thesis is no good, and
sibling arguments also using Godel's
Incompleteness Theorem to establish
something similar are doomed?
Much obliged,
--> F.A. Muller
*****************************************
Dr F.A. Muller
Fac. Physics & Astronomy
Utrecht University
f.a.muller at phys.uu.nl
&
Fac. of Philosophy
Erasmus University Rotterdam
f.a.muller at fwb.eur.nl
The Netherlands
*****************************************
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