Re: terminal von Neumann

[Tim Gwinn <***>]

JohnK,

As to the "best reference", I have access to neither the 1951 paper or Burks
1966 book. All I can say is that Rosen (1959) references the 1951 paper. I
wish von Neumann's work's was more widely available, but like so many
seminal thinkers, his works seem to be inordinately expensive or hard to
find. :(

As to the confounding simulation and construction remark in Life Itself, the
remark occurs in the discussion of the use of a Rosennean 'machine' employed
to run a 'simulation' (in Rosen's terminology). What follows is a quick (?)
review of that discussion. (Other detailed discussion takes place in chapter
7, "On Simulation".)

Consider the following model of a Rosennean 'machine', listed as [9E.4]:
  f => A -> B
(where "=>" is efficient cause and "->" is material cause)

In this case, f is the efficient cause generated by the machine hardware,
"A->B" represent the flow between sets of the machine's software states as
induced by the hardware. The idea is that natural system's which are
'machines' have such a relational model. And the definite distinction
between hardware and software in the natural system is maintained in the
model. So, we can go back and forth from the model to the natural system and
know that the efficient causes and material causes and the distinctions and
relations between them are maintained congruently.

Now (omitting the details on how it arises) consider the following, listed
as Fig 9E.1:
  Phi => X -> f => A -> B
Rosen notes that we can write Fig. 9E.1 as:
   Phi => X -> B
provided that we interpret
   X -> f => A -> B
(which is [9E.5]), as a single software flow.

What this does is make
   Phi => X -> B
superficially appear to be of the same general form as
   f => A -> B
which was the process [9E.4] we wanted to have as a model. However, now the
process [9E.4] occurs entirely INSIDE of a software flow, namely  "X -> B".
So, process [9E.4] is no longer a software flow induced by hardware.
Instead, [9E.4] ("f=>A->B") is now entirely composed of software flow. It
has now become a SIMULATION of a hardware/software process. We have lost the
congruence of the distinct causal categories between the natural system and
our 'model' since "f=>A->B" is now entirely just a section of material cause
in the software flow "X->B".

There are a couple of issues that arise. The first is that the simulator
"Phi => X -> B" has nothing to decode back to in the natural system: there
is no congruence of entailment structures between the simulator and a
natural system. Thus, the simulation occurring *inside* the software flow
"X->B" cannot necessarily be decoded back to a natural system. Also, now
that "f=>A->B" is composed entirely of software states it becomes completely
malleable in interpretation: we can now manipulate the software states f, A,
B all we want if we consider them as data, and then we can change
interpretations and reconsider them as the mapping "f=>A->B". We can flip
back and forth between these kinds of interpretations of the software
states, and in doing so, we can perform all kinds of manipulations that have
no correspondence with those in a natural system. These kinds of
manipulations of states can give the appearance of, among other things,
constructing a self-modifying or self-reproducing system inside the
simulator, which can lead to the notion that such simulations make for an
accessible and practical way to study these kinds of system. But these sets
of manipulations do not generally have any corresponding decoding to a
natural system; much less the simulator (in which this all must occur) have
any such decoding either. Thus, as Rosen says "Nothing could more starkly
illustrate the anomolous character of simulation and the mischief that can
arise through the confusion of causal categories."

Regards,
Tim



> -----Original Message-----
> From: ROSEN Forum [mailto:*** Behalf Of John
> Kineman
> Sent: Monday, April 05, 2004 8:52 PM
> To: ***
> Subject: Re: terminal von Neumann
>
>
> Tim, I greatly appreciate your digging into these references, which I
> wanted to do but couldn't find the time. I would like to cite something
> about the logical paradox. What is the best reference for that, the 1951
> paper or 1966?
> Also, thinking this weekend and reading more of AS and searching on the
> web for articles on Von Neumann, it became clear that VN is associated
> with the Church-Turing concepts of computablility and responsible for
> essentially inventing modern computing and cellular automata techniques.
> Chris Langton of SFI developed agent-based modeling automata in a
> sofware package called SWARM. It has been used to model many complex
> biotic interactions on a landscape, like species competition and
> evolution, predation, etc. I am using such a technique myself to model
> shrub encroachment (or at least have proposed to do so).
>
> As I have now reasoned it from this cursory exposure to Von Neumann, via
> all the comments here and various articles on the Web, I sense that the
> issue of "confounding" simulation and construction is a very simple one
> to distinguish. VN proposed the idea of a "universal constructor" as a
> logical entity based on self-replicating logical structures, i.e.,
> computer programs. I'm guessing that idea of self-replicating structures
> is what is meant by cellular automata. However, it is not a case where
> the agents write their own software, the software written by a human
> programmer allows for certain characters of the agent to be modified in
> each iterative step, the steps themselves being under control of the
> programmer. I don't know if anyone has succeeded in generalizing this
> concept to the point where the agents write their own software in its
> entirely - I suspect not because that would run into difficulties with
> Goedellian incompleteness. In that case, it only works within a given
> context - a context given by the programmer, a biological entity. In
> realizing any such self-reproduction in the natural world, one would
> also have to realize a context and the semantic relationship with that
> context. On logical grounds, RR says that would not be possible,
> precisely because the model must remain calculable in VN's approach, and
> thus semantically incomplete. To be realized, natural systems must be
> semantically complete. This to me seems to explain the comment that VN
> confounded simulation with construction - it was not that VN didn't
> realize or discuss the same problem, it was that his proposed solution
> involved making a direct analogy between what could be done in the
> computer via calculations and what is happening in nature, and then
> speculating that the one could cause the other, or be realized by it. RR
> said that cannot happen unless the "model" is a) itself part of a
> natural system, and b) non computable. Self-realization of a program
> that could write its own software and construct its own hardware would
> satisfy criterion (a), but he argued that on logical grounds it could
> not do that and remain computable. That to me seems to be the debate. Is
> this at all close according to your sources????
>
> John Kineman