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Re: terminal von Neumann
- From: Howard Pattee <***>
- Date: Fri, 2 Apr 2004 10:58:09 -0500
Tim,
I accept the list?s consensus that the von Neumann discussion should not continue since
it is apparently causing so much grief. However, you said you would welcome seeing the
von Neumann quotes that I promised, so here they are.
I emphasize that there is one and only one issue these quotes are chosen to address. It
is Bob?s statements (I apologize for using ? accusation?) that von Neumann did not
distinguish computation from construction. I repeat here only one of Bob?s statements
from LI. (The others were not parenthetic.):
Rosen: ?I remark parenthetically that the confounding of simulation (computation) with
construction, which lies at the heart of, e.g., von Neumann?s well-known discussion of
?self-reproducing automata,? arises precisely here and rests entirely on the equivocal
and inconsistent hardware/software distinctions to which I have just called attention.?
HP: The only issue I have ever meant to raise, is that von Neumann?s extensive
discussions show that this assertion has no basis in fact, and I am sorry if my careless
language implied otherwise. All your other discussions are interesting, but are not at
issue since none of the other authors assert that the problem is von Neumann?s
?confounding.?
I have never found in Rosen?s papers or anywhere else any specific evidence, such as
direct quotations of von Neumann, or even a reference to a specific page or section of
his voluminous writings, which suggests such confounding. My teachers and colleagues in
physics, some of whom knew von Neumann well, felt that Rosen?s claim was unfair and
unwarranted, and unfortunately this has biased them against his important ideas.
There are also a few clarifications needed.
Tim: According to Burk, [Arthur Burks] there were two models of "self-reproducing
automata" proposed by von Neumann: the kinematic automaton and the cellular automaton. I
believe it is in regard to the latter model, the one which was developed into more detail
(e.g., the 29-state machine) by von Neumann, that Rosen is addressing his remarks.
HP: No. That is incorrect. Bob?s 1959 paper, written while still a graduate student, was
about the kinematic model (according to Bob in video interview, 4/23/98, by Peter
Cariani). The cellular automaton model is the one (of actually five models) that von
Neumann wanted to ?axiomatize? because he could not define precisely enough the kinematic
model. It is the cellular automaton that has the big interpretational problems just
because a computer cannot actually construct anything. It can only simulate construction.
This is why von Neumann warned that axiomatizing, ?throws half the problem out the
window, and it may be the more important half.? But von Neumann always stated clearly the
need to distinguish between formal logic (computation) and construction even in the
axiomatized cellular automata.
Von Neumann (Theory of Self-reproducing Automata, Pt. 2, Chap. 1, General
Considerations, p. 91):
?The methods that will be used in this paper contribute, however, only very partially to
the effort that is needed in that direction [the thermodynamics of construction], and at
any rate, we will limit ourselves at this occasion to the establishing of certain
existences (by suitable as hoc constructions) in the sense outlined above.?
?1.1.2.1 The main questions: (A) ? (E). Within the above limitations, however, we will
deal with problems that are rather central ? at least for the initial phases of the
subject. We will investigate
automata under two important, and connected, aspects: those of logics and of
construction. We can organize our considerations under the headings of five main
questions.
(A) Logical universality. When is a class of automata logically universal, i.e., able to
perform all those logical operations that are at all performable with finite (but
arbitrarily extensive) means?
(B) Constructability. Can an automaton be constructed, i.e., assembled and built from
appropriately defined ?raw materials? by another automaton?
(C) Construction universality. Making the second question, (B), more specific, can any
one, suitably given, automaton be construction universal, i.e., be able to construct in
the sense of question (B) (with suitable, but essentially standard attachments) every
other automaton?
HP: Von Neumann?s last two headings are (D) Self-reproduction and (E) Evolution, which I
will skip. If you read this far and still claim that "von Neumann confounded computation
(simulation) with construction" then I doubt going further will help. But I will try,
since he only gets more explicit about the differences between formal logics
(computation) and construction.
Von Neumann (ibid. pp. 99-101):
?1.2 The Role of Logics ? Question (A)
1.2.1 The logical operations ? neurons. In evaluating question (A), one must obviously
consider automata which possess organs that can express the essential propositions of
logics and which need not possess any other organs. This can be done by using organs each
of which possess two stable states, corresponding to the basic truth-values of true and
false in logics. It is convenient to use a plausible physiological analogy and to
designate these organs (whatever they are or are thought to be in reality) as neurons,
and the two states as excited and quiescent, respectively.?
HP: Von Neumann goes on for two pages on logics that are essentially what is needed for
Turing-equivalent computations, and then he takes up construction that he describes as an
entirely different type of activity:
Von Neumann (ibid. pp. 101-111):
?1.3 The Basic Problems of Construction ? Question (B)
1.3.1.1 The immediate treatment, involving geometry, kinematics, etc.
The most immediate approach is this. The constituent organs are the neurons and lines
necessitated by (A), plus such additional organs (B) will require. These constituent
organs are to be conceived of as physical objects in actual space. Their acquisition and
combination (including the establishment of rigid connections between them) must
accordingly take place in actual space.?
HP: Von Neumann goes on in more detail for about 10 pages that I will skip (I am not
taking anything out of context.) It?s all about implementing construction as
distinguished from logics and computation. I have used only one von Neumann reference.
There are others; but as I said, if the above quotes are unconvincing, more quotes won?t
help.
I want to reemphasize that whether von Neumann?s automata actually work or not is not the
issue. Also as I said, Rosen?s formally correct argument is not at issue. As a matter of
fact, von Neumann was well aware of the same basic argument that Rosen used (a form of
antinomy of the Richard type, i.e., the self-reference paradox of sets that are members
of themselves). He discussed it at length (ibid. pp. 122-126.) and shows how it might be
avoided. I feel sure that if Bob had read it before 1959 he would have agreed and saved
everyone a lot of grief.
I also feel it is ironic, and over the many years, contrary to Bob?s interests, that he
never refers to those ideas of von Neumann?s that were not contrary to his own,
specifically (1) the basic epistemology of Hertz, (2) the inadequacy of physical laws to
explain life, (3) the irreducibility (unentailment) of measurement (coding), and (4) the
difficulties of modeling life by any formal computation.
Howard