Replies

" Even assuming "defect" "

It's not an assumption, it's a fact.

"it still assumes that the inactivation is the result of a mutation..."

Not an assumption.

"that the mutation is random (not caused by some mechanistic viral or enzymatic activity)"

Irrelevant. The damaged gene was passed on from generation to generation. It doesn't matter how it was damaged; only that it was damaged. In the same spot on the gene, in multiple lineages.

"and says absolutely nothing about how the ancestor that possessed the purportedly functioning gene came to exist, whether it descended from a universal common ancestor, descended from one of many independently created organisms, etc."

The gene exists in other mammals. It is defective in apes, at the same spot.

"Just because there may not be a plausible alternative explantion readily apparent at present doesn't mean that one's preferred hypothesis of universal common descent should be considered, for all intents and purposes, proven."

It does when the evidence is as strong as it is.

" That's a logical fallacy."

Only the way you presented it. That isn't the way scientists present it.

"It is simply impossible at present to calculate the probabilities of independent occurrences of inactivating mutations because of lack of complete knowledge of all past and present mechanisms of mutation."

That invalidates all the probability calculations that ID'ers promote.

"(There is evidence of insertion bias in some ERV's for example.) "

The bias is very slight; and we are not talking about ERV's here.

" So the conclusion of common ancestry based on this line of evidence should be considered, at best, one tentative alternative."

It's not *proven* in the mathematical sense, but it is overwhelming to anybody not overcome by prior ideological positions. That some many independent lines of evidence would point in the same direction by chance... is not something that a reasonable person will accept.