X-Message-Number: 8257
From: 
Date: Fri, 30 May 1997 12:09:07 -0400 (EDT)
Subject: probability, psychiatry

Perry Metzger (# 8251) shows his limited understanding of the foundations of
probability theory.

My own view, developed independently about 45 years ago, turns out to be
similar in some ways to those of important historical figures including
Frechet and Reichenbach. It was presented as an essay for the M.A. in math,
and pronounced kosher by professionals in the field. A partial version of it
is available from the Immortalist Society in the form of a booklet: CRYONICS:
THE PROBABILITY OF RESCUE.

I won't say much here, but note that Metzger says of certain assertions that
they are "true or false" and there exists no statistical background on which
to base probability assessments. He is wrong. Very briefly:

First, every assertion of alleged fact is true or false; this obviously does
not make probability inapplicable. 

As one obvious example, consider coin tossing. The probability of getting
heads on the next toss is (usually, approximately) 1/2; no one disagrees. But
now consider a coin already tossed but not yet examined. According to
Metzger's reasoning, this is beyond the purview of probability; we either
have heads or we don't. But for purposes of betting, the situation is exactly
the same as in the case of a future toss, and we use probability in the same
way. Probability is objective in the sense of resting on experience, but
subjective in the sense that it depends on the experience of the OBSERVER. 

Second, Metzger's notion of a necessary statistical basis is simplistic. We
do need such a basis, but if necessary we can look at broadened categories. 

As an extremely simple example, some considerations in probability
calculations (or making bets) apply not only to football games but also to
basketball games. If I invent a new kind of ball game, with no background of
experience, is use of probability out of the question? Of course not; I just
look at the broader category of ball games in general (which may or may not
require rougher calculations).

If someone says an invisible bunny is following him around, is there any way
to judge the probability that the assertion is true? Again, certainly. We
know from experience that people frequently make such statements either as
jokes or as an illustration of some theoretical argument. Since we have
minimal reason to believe the assertion and plenty of reason to reject it,
there is an overwhelming probability that the assertion is false. This is
just a short-hand application of the general principle noted above....And
anyone who claims not to subscribe to this principle will have to explain
why, in practice, he uses it every day in countless ways.

P.S. Metzger also does me the kindness of psychiatric evaluation without
charge, saying my skepticism about feeling in robots is based on "religion"
or on a need to feel superior. How this conclusion can be reached from
reading anything I have said is itself a psychiatric problem.

Robert Ettinger

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