Re: Am I a token or a type?

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Tue, 6 Aug 2002 12:29:46 +0200

Lennart Wilson:

> >The way I see it is that we DO have to run the UD on a VERY specialized
> >machinery.......


Bruno Marchal:
> Which one? and Why? What will be special about that machinery and
> how that "special" things does play a role in our experience.
> (Perhaps you are right but that seems to me incompatible with
> the comp hypothesis, imo).
> And where would that very specialized machinery comes from?


LW:
I think that is for the science of physics to find out and not a question of
logic.


BM:
It is your right to presuppose physicalism at the start, although I
agree with John Archibald Wheeler that we cannot explain the origin of
physical laws with a physical law.
Also I have shown that physicalism must be rejected if the comp hyp is made.
In a nutshell, if comp is true, the physical laws emerges from a coherent
structure of sharable machine computations, basically just (sigma_1)
arithmetical sentences.
I don't doubt that physics can inspire and help in the TOE
search process, but concerning even just the formulation of the mind body
problem and the problem of the origin, pure math, logic and computer
science are in better position.


LW:
  I tend to like this statement from a member of the avoid-l.domain.name.hidden
list /Lennart


BM:
OK. Don't hesitate to give him a chance to answer my comment.


MEMBER of the avoid-l.domain.name.hidden /Lennart:
" Questions about the validity of rules of inference generally arise
because of the opaqueness of one or more of the primitive terms adopted for
a given system. As long as you stick with 'and', 'not', and the other
well-understood terms, you usually encounter no difficulties, because the
presystematic usage, and the explanation of this usage (outside the sysyem
proper) is crystal clear.The details of the use of these terms is then
subsequently elaborated by their use in the definitions and theorems of the
system. Even here, however, there was, initially, some reluctance to accept
'if...then...' as material implication. The opponents were, in essence,
shouted down, because of the prior habits in the use of Modus Ponens. In
quantification theory 'for all...' and 'for some...' don't generate much
contraversy until you begin to introduce identity '=' . Thank You Leibnitz!!


BM:
OK. (but see nuances below).


MEMBER of the avoid-l.domain.name.hidden /Lennart:
    The problems that occur with 'possible' stem from the facts that 1) there
is no prior agreed-upon clear meaning of the term presystematically and 2)
none of the formalized systems, from Lewis on, shed much further light on
the (what I would call 'inherent') obscurity.

BM:
Which Lewis? C I Lewis I suppose. Gosh, he paves the way of modern
modal logic, but it is the work of Scott, Montague, and Kripke which
has transform modal logic into a respectable branch of pure and applied
mathematics, with many application in engineering. Look at the
thesis of Jennifer Davoren for a good example. Not to mention the result
by Solovay which axiomatizes the consequence of incompleteness (and
play a fundamental role in my derivation of physics from "machine's
machine psychology".


MEMBER of the avoid-l.domain.name.hidden /Lennart:
    An instructive quote '...if we decide that a given term (say
'ectoplasmic'), because of its presystematic usage,is not amenable to
clarification, we do not take it as primitive - but then neither do we
define it in the system.' - Nelson Goodman, 'The Structure of Appearance',
III,2.
    'Possible', 'necessary', 'cause', 'conscious', 'essence', etc., etc. do
not and should not occur in formalized scientific systems precisely because
their presystematic usage is so confused and ambiguous."


BM:
I would say that, when terms are confused and ambiguous, it is a motivation
for axiomatizing them into formalized scientific theories. If not, *new*
sciences just cannot appear!
Word like 'Possible', 'necessary', 'cause', 'conscious', 'essence' occurs
in a lot of interesting papers, from Aristotle to Deutsch :-) (Unlike
'ectoplasmic" which appears only in 19th science fantasy books and in
admittedly unsuccessful work in parapsychology).

Concerning "possible" and necessary, I believe the exact contrary of the
text you quote. Modal logic is the greatest achievement of Aristotle, but
he makes the idea in a too much clear way that people thought that modalities
could be unique and have search universal application of only one modal
logic, the so-called S5 system:

    AXIOMS: [](p->q)->([]p->[]q) (Read []p p is necessary, and
            []p->p <>p p is possible).
            []p->[][]p
            <>p->[]<>p
    RULES: Modus Ponens, Necessitation (from p, infer []p)

This is so true that in a visionary paper,The Ghost of Modality, Hermann
Weyl almost discovered at once, the provability modal logic, the probability
modal logic, the epistemic modal logic, the quantum modal logic, and
rejects them all because none is formalised by the S5 system!
This would be like formalising Group theory by Commutative Group theory,
and rejecting all groups after discovering a non abelian group!

Bruno


WEYL H., 1940, The Ghost of Modality, in Philosophical Essays in
Memory of Edmund Husserl, Marvin Farber ed., Harvard University
Press. Traduit et commenté en français par Jean Largeault, Le fantôme
de la modalité, dans
Weyl,Le continu et autres écrits, Vrin, Paris, 1994.
Received on Tue Aug 06 2002 - 03:37:17 PDT