Tom Schneider, “Mr. Information Theory” for the pro-Darwin side, criticized Lee Spetner (author of *Not a Chance*) for a probability calculation characterizing evolutionary processes. Here is a reply by Spetner that I’m posting with his permission:

Someone just brought to my attention the website http://www.lecb.ncifcrf.gov/~toms/paper/ev/AND-multiplication-error.html

which criticizes a probability calculation I made. . . .Schneider is mistaken. He evidently did not take the trouble to understand what I was calculating. My calculation is correct. The probability 1/300,000 is the probability that a particular mutation will occur in a population and will survive to take over that population. If that mutation occurred it would have to have had a positive selective value to take over the population. If that occurred, then all members of the new population will have that mutation. Then the probability of another particular adaptive mutation occurring in the new population is again 1/300,000 and is independent of what went before Ã¢â‚¬â€œ I have already taken account of the occurrence and take-over of the first mutation.

Therefore, the correct probability of both these mutations occurring and taking over their populations is the product of these two probabilities. And, as I wrote, the probability of 500 of them occurring is the probability 1/300,000 multiplied by itself 500 times. My calculation is correct and Schneider is mistaken. He is similarly mistaken about what he wrote about the article in Chance – Probability Alone Should End the Debate, http://www.windowview.org/science/06f.html, since that article relied on my calculation.