Re: Mammalian eyes...

Brian D. Harper (harper.10@osu.edu)
Sat, 09 Nov 1996 01:18:25 -0500

At 12:41 AM 11/8/96 -0800, Randy Landrum wrote:

quoting Michael Denton:
>The only way Darwin could have countered these doubts would have been by
>the provision of rigorous quantitative evidence in the form of probability
>estimates to show that the routes to such seemingly remarkable ends could
>have been found by chance in the time available. To have estimated the
>probability that a purely random search would have discovered the route
>(or routes) to the eye, for example, he would have needed to have mapped
>out all possible routes that evolution might conceivably have taken from
>the original light sensitive spot over the past three thousand million
>years adn then to have determined the fraction of routes which lead to
>"camera type" eyes adn the fraction which lead to all other less
>sophisticated organs of sight. Only then would he have been able to
>counter his critics with quantitative evidence that such seemingly
>improbable ends could have been hit on by chance."
>

This is a typical misuse of probability. Computing the ratio suggested
by Denton is totally meaningless unless one supposes that all possible
routes are equally probable. A ridiculous supposition as far as I'm
concerned. Why on earth would one assume such a thing?

BTW, the word random can mean a variety of different things depending
upon the context. As some wise person once said "we have more concepts
than we have words to describe them". In probability theory random may
often mean what is suggested by Denton above, e.g. an arbitrary choice
among a number of equally probable alternatives. In Darwinism
[random mutation + natural selection] random generally means only
that the occurance of a mutation does not anticipate the needs of an
organism. It certainly does not mean that all evolutionary paths are
equally probable.

Brian Harper | "If you don't understand
Associate Professor | something and want to
Applied Mechanics | sound profound, use the
The Ohio State University | word 'entropy'"
| -- Morrowitz
Bastion for the naturalistic |
rulers of science |