From: simon@dcs.warwick.ac.uk (Simon Clippingdale)
Newsgroups: alt.atheism
Subject: Re: Do Atheists Have Their Own "Faith"?
Date: 15 Apr 92 12:30:19 GMT
Organization: Department of Computer Science, Warwick University, England


I've been asked by email:

> Could you please post the reasons why you
> think z is justifiably close to zero?

so I'll try, although I wasn't reeeeeally intending to get into this.....


I'm assuming that the e-mailer meant the probability of existence of
god/s, rather than All-Creating Higher-Dimensional Huge Blue Banana/s.
Luckily it doesn't really matter, since I don't personally think the
figures or, in essence, the logical constructs, are any different.


There is a symmetry-based argument in probability which is known as the
Princple of Insufficient Reason. It states, roughly speaking, that if we
have a number of possible outcomes of an experiment and we have no idea
about their respective probabilities of occurrence, we *must* assume that
these probabilities are equal. The reason is that if the i'th outcome (NB
no particular order implied) is denoted by Q(i) and its probability by
P(i), and if we assign *different* values to each of the P(i), then an
arbitrary permutation of the indices i changes the probabilities P(i)
without any basis for the change in reality. Or: "expect a coin or a die
to be fair unless and until you have *reason* to suspect otherwise",
loosely speaking.

From Papoulis, "Probability, Random Variables and Stochastic Processes",
2nd.edition, McGraw-Hill, 1984, p.8. (slightly different notation):

       "This conclusion is based on the subjective interpretation of
        probability as a MEASURE OF OUR STATE OF KNOWLEDGE about the
        events Q(i)." [emphasis in original]

Essentially, my position involves taking this permutation-symmetry argument
and turning it to my own wicked ends, viz:

If there is (as far as I'm concerned [see quote]) an equal amount/lack of
evidence for any number of theories of, say, the origin of the universe, then
I am compelled to award each of them the *same* notional probability z of
being true, at least until some evidence comes along to separate them. On
this basis, god/s and All-Creating Higher-Dimensional Huge Blue Banana/s
score exactly the same.

As to the actual *value* of z, well, consider the number of such theories,
`a la Blue Banana, which exist. I can, indeed, invent at will theories
which I consider to be as well-supported by evidence as the god/s theory/ies
or the blue banana theory. There are clearly an arbitrarily large number
of such theories, and since their probabilities must sum to 1 (*) and must
be equal from the above, the inevitable conclusion is that z for each is
asymptotically zero (the "asymptotically" is there because I can't actually
entertain an infinite number of theories, since I don't anticipate being
around that long or wasting any more time on crap than I have to).

(*) under some fairly straightforward conditions of mutual exclusivity.


There you just about have it.


Before I am offered reams of scriptural "evidence" by Christians, Clausians
or Bananaians (pronounced ba-na-*nay*-uns), please note that I *have* seen
lots and lots of evidence supporting the theory that the religious memes
are extremely potent. Don't bother wasting bandwidth giving me any more;
I already believe that theory.

Magic yourself up in my office, say "God sent me" or "The Banana sent me"
or whatever, and hell, we'll talk....:-)


Cheers

Simon
-- 
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"Every morning when you wake up and look in the mirror, check yourself
for signs of collective identity" - Consolidated on "This Is Fascism"
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