Iain,
I think your missing my point. What we have is an end point with a
probability of 1. We don't know the starting point. We don't know the
process, but every little while we get a new insight that provides an
additional mechanism. If we were computing probabilities on the basis of
what was known about a century and a half ago, we'd have given the
probability of evolution at ~0 or 10^(infinity), for it was held to be a
logical impossibility. We now get someone who calculates ~10^1000. Want
to extrapolate the rate of change to the next century or even decade?
Dave (ASA)
On Mon, 12 Nov 2007 14:44:25 +0000 "Iain Strachan"
<igd.strachan@gmail.com> writes:
On Nov 12, 2007 1:43 PM, Alexanian, Moorad <alexanian@uncw.edu> wrote:
I do not think anyone knows how to calculate possible outcomes from given
initial conditions. Unless one can know what the possible outcomes can
be, how is one to calculate probabilities for individual outcomes? One
does not know dynamics that well to make any sort of predications.
I think this is rather missing the point of Koonin's argument.
His argument is to take the current front-runner theory of the origin of
life (RNA - world), and the assumption that in order to kick start the
process of evolution, we need to have translation and replication in
process. This is a chance event that has to happen once only. Then,
given generous estimates of RNA replication rates, and of the number of
planets in the observable universe, ... under all these assumptions, then
he finds that the probability of this chance event, for which he has done
a conservative estimate, is vanishingly small for a single universe. And
what you have is a conservative estimate, with RNA jiggling about on
every square millimetre of every planet in the universe whether
hospitable for life or not. The real probability (which we can't
estimate) is likely much smaller, but we've at least had a shot at an
upper bound.
The reason I don't find this valid is probably the same as yours, David's
and Michaels - ie that we don't know how it might have happened, and that
therefore, if the current model gives a vanishingly small probability of
it happening then the current model is wrong and we haven't solved the
problem. A better theory will no doubt emerge in time as we get to know
more, which gives a much higher probability of life starting up. The low
probability argument proves neither the multiverse hypothesis, nor the
Intelligent design hypothesis. All it proves is that we don't know yet
how life got started up.
What I was objecting to is the notion that you can airily dismiss it by
saying "oh... well extremely unlikely events happen all the time".
That's what I think is a silly argument. Supposed you were facing a
firing squad, or marksmen whose guns were loaded with live or blank
ammunition based on a coin-toss. 100 bangs go off and you walk away
unscathed. Are you really going to walk away with a shrug of the
shoulders and say "well, 100 heads is just as likely as any other
combination, so I'm not surprised I escaped at all"? Of course not,
because with any of the other 2^100-1 (equally likely) possibilities you
are going to end up dead.
Iain
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Received on Mon Nov 12 13:43:41 2007
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