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OK, lets work with that analogy. It will help you get straight on some basic concepts, like the relation between observation and theory. Question: What must be true in order for an observation to count as evidence in favor of a theory? Answer: The conditional probability of the observation given the theory must be greater than the conditional probability of the observation given the denial of the theory. (Bayesians: I'm on your side, but Paley's argument seems to presuppose Edwards Likelihood Principle so let's play along for the sake of agrument.) Apply that to the watch example: The conditional probability of finding a watch given that there was a designer is greater than the conditional probability of finding a watch given that there was no designer. So far so good? OK, now apply that principle to the present case. Paley didn't have the wealth of observation to work with that we have now. So he might be making a reasonable inference from the information available to him and _still_ be as wrong as people in the 3rd century BC who inferred the world was flat because gosh darn it looked flat. Observation: There are structural similarities between creatures that have no functional explanation. Ie two legged and four legged mammals have the same skeletal structure. Apply the likelihood principle. Is the conditional probability of this observation greater assuming the truth of intelligent design or is it greater assuming that two legged and four legged animals have a common ancestor?

Ie two legged and four legged mammals have the same skeletal structure. Apply the likelihood principle. Is the conditional probability of this observation greater assuming the truth of intelligent design or is it greater assuming that two legged and four legged animals have a common ancestor?

You are applying that likelihood principle in a very selective manner. If a two-legged mammal and a four-legged mammal have some similarities but a vastly larger number of differences, I'd say the likelihood principle would not favor a common origin. I can be six feet tall and weigh 200 pounds, but the fact that a log in the woods is six feet tall and weighs 200 pounds does not mean we have a common ancestor.

In addition, you are making my case when you state that reality is largely a matter of human perception. If the people of the 3rd century B.C. were incorrect when they assumed that the world was flat simply because every piece of evidence seemed to indicate that this was the case, then what credence should I give to anything that is passed off as science today? Human perception cannot be the defining influence in what is known as "truth," especially when you can cite so many cases where we clearly understand it to have been wrong!

I should also point out that any testing of competing theories based on "probability" is pretty pointless when you have already negated the possibility that one of the theories is correct. The man walking on the beach who picked up the carved figurine had two basic theories to test: 1) the carving was man-made, or 2) the carving was the result of the random forces of wind and rain. If he had his mind set on the notion that a man could not possibly have made such a carving (i.e., he has determined that the probability of a man-made origin is zero), then he will naturally conclude that the piece of wood was formed by the forces of nature no matter how miniscule the probability that it could have been formed that way.

What is particularly interesting in this example is that the man who finds such a thing could re-affirm his belief in a "random" origin by conducting an experiment that follows the scientific method perfectly. He can try to make a carving on his own, then have every person in the village where he lives try to do the same thing. If nobody can make an identical carving, then he would logically conclude that these things could not have been man-made!