August 10, 1955

Dr. John von Neumann
Atomic Energy Commission
Washington 25, D.C.

Dear Dr. von Neumann:
Thank you for your comment of the 8th on self=reproduction.

First, I sea that I should clarify what I meant by "begging the question",
both to you ani, by amending the text, to the readers of the article. Although
ths phrase has logical connotations. I was referring to material content. That
4s, I suspsct that any working model that could be built, actually would have
wonsiderable information inherent in the available parts, regardless of the
logical possibility of a machina that would be indifferent to its environment.
But this is no different from any organism, whose self-sufficiency 41s also
qualified, Ordo I mimanderstand the sense of information content? If so,
what (in a biological context) would be an experimental criterion of self~
suffictency of Informattlon?

My suspicion that I do not understand what "information" means is strengthened
by reading your argument. It hinges on the word "Andependent". Am I wrong to
think in terms of seta? Then, M and A would overlap; A' could include A. However,
your second premise (in the final syllogism) is that "since A’ can produce A, the
information content of A must be contained in A'. Is this consistent with the
condition that At produce A if [and only 1f7] A’ is immersed in M?

If "information" ie construed here as the rule of behavior that A or A! is
to follow J@ a miitable environment, M, is encountered, I see that my objections
could be countered. The experimental#blological problem would bs deepened, as
we can only detect whether a given situation works, and I do not know how we
tell whether it is instructions or materiel that is lacking. In this event, then
"biological specificity" would have an even broader content than information,
and I would merely substitute the terms in my account. I would also be more
discouraged about the possibility of learning something that could be put to
good use dn the laboratory.

I do not want to impose on your tims; whatever you can spare for this might
be put down to instruction, which I would be grateful to have.

Yours sineerely,

Joshua Lederberg
Professor of Genetics