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21 Février
2002
Jean-Paul
Baquiast et Christophe Jacquemin
(French) Traduction : Maureen
Smith
Regarding the
lambda-calculus
In
a dossier aiming to be explosive, (perhaps one of the most important
discoveries of all time), the review Science and Vie no. 1013 of February
2002 presented to the public what, according to the authors, a conceptual
revolution of the first order could be. It's about a hypothesis (or
theory) put forward by the French logician and mathematician Jean-Louis
Krivine, according to which the brain-based logic functional strata,
just above the physical architecture of the neurons, would use a language
close or analogous to lambda-calculus. The latter is a logical language
invented in 1932, thus before the appearance of computers, by the
mathematician Alonzo Church. It allows for three rudimentary grammatical
processes, which programmers later discovered form the basis of all
the operations asked of a computer: specify the address of the instructions,
specify the address of the data and to carry out operation.
The contribution of Jean-Louis Krivine was to show that these same processes
are to be found at the base of all reasoning and mathematical structures.
As the mathematician ascends into abstraction, these superposed strata, which
become more and more complex, can always be reduced to the programming rules
of lambda-calculus. In this context, the mathematician demonstrated that the
non-fulfillment theorem of Godel* could be reduced to a simple computer program
expressed in lambda-calculus. A program, which "would resemble a file
repair program", implemented by a computer operating system in case of
an unexpected breakdown of the system. The program itself, according to a
hypothesis by Krivine, could be similar to what happens in the brain when,
during sleep, all the previous evenings programs are shut down to allow the
restoration of the cognitive contents in order to face the hazards of the
following day, maintenance processes of which dreams could be vague echoes.
The presentation of Jean-Louis Krivine's research shows amply that the work
he accomplished was important, arriving at the apparently simple conclusion-
even if revolutionary- that all human language, diverse languages like cognitive
construction, including mathematics, could have been built by the brain using
lambda-calculus instructions. From this perspective, the most famous mathematicians
and scientists are therefore only, if one can so say without violating their
grandeur, PC computers exploring the world.
In a Darwinian, evolutionary hypothesis which seems indispensable to the
coherence of this grandiose vision, it will be right from the first appearance
of the nervous and nevraxes cells, in species of multi-cellular origin, that
the lambda-calculus logical supports will be constructed. It is a survival
tool, which allows them to adapt as quickly as possible to the constraints
of the environment.
The appropriateness, more or less marked, between mathematics and the world,
which has always surprised philosophers, will no longer be more surprising
than the appropriateness, for example, of retina cells to the source of light
waves. In all organisms characterizing living beings such as they are today,
including the brain, one thus finds a co-evolution between the organism and
the environment, which never ceases to exist.
This co-evolution will effectively continue in the future, thanks to the
development of mathematics in partnership with computer science, producing
more and more autonomous information systems: be it in the field of artificial
life (with a progressive ascent towards the nano-technologies) such as those
of artificial intelligence.
But one can also think that bringing the elementary processes of brain function
to the fore would better allow us to understand, the smallest and most complex
languages and symbolic exchanges of animals. One could well end up accepting
that all animals are capable of algebraic or geometric calculations carried
out in lambda-calculus, even if these calculations cannot be expressed for
us in mathematical formulae. Which goes to show that animals could also well
have a seat of consciousness not yet perceptible by us, such as still incomprehensible
mathematical calculations - much less, that all this will not be compiled
in the common terms of lambda-calculus. For a theoretician of artificial consciousness
such as Alain Cardon, however, such an approach finds its limits in fact even
if it comes from information technology, for which all is calculable to the
nth degree. The lambda-calculus brought us Turing's machine. Thought is something
different. To understand it, one has to call upon other approaches, such as
René Thom's continuum.
One could conclude this brief discussion by taking the conclusion proposed
by Jean Petitot, director of the Centre de Recherche en Epistomélogie
Appliqué de l'Ecole Polytechnique, questioned by Science et Vie: a
vast and urgent interdisciplinary research program is essential in order to
really understand how the brain thinks consciously, as much in the human as
in the animal. All this leaves us to suppose that we are waiting to see "the
emergence" of revolutionary concepts around the concept of this subject
grasping the idea that this is a subject - a problem that our "sameist"
friends return to when they ask themselves what has happened when "a
same" realizes that he is "a same" - which happens to us daily
when we ask ourselves about the sameness of the composition of our thought.
* Demonstrated
in 1931, this theorem affirms that truths always exist that mathematics
cannot demonstrate.