Swan also asserts, "SETI does not claim ETI on the basis of calculating, or asserting, a low probability the nonexistence of ETI." Well, first of all, SETI does not yet claim ETI at all. But if and when it does make such a claim, it will be based on a low probability that the signal came from anything other than an intelligent source.

I claimed, "If and when SETI gets positive results, those results will likely be the only evidence we have for ETI." Swan calls this laughable, replying "Actually, SETI has gotten positive results, which were then discarded when it was shown that they were likely produced by a purely-natural and nonintelligent phenomenon." What he should have said is that SETI has obtained what at first appeared to be positive results but which, on closer analysis, turned out not to be positive.

He points out that positive results could be verified by other procedures. I agree that this is possible, but my point was simply that it is not necessary for a valid design inference.

Swan writes, "It is ID that makes the claim for the low probability of the unguided, nonintelligent natural evolution of phenomena. The ball is in its court to demonstrate the validity of its assertion, not for science to prove the assertion to be wrong."

Not really. Let's take the set of all irreducibly complex systems that we know of and divide them into two classes. First, there are the IC systems whose origin is thoroughly known to us, such as microprocessors, mousetraps, etc. Second, we have the IC systems whose origin is unclear and disputed: flagella, etc. The things in the first class are all created by intelligent designers. The things in the second class are the very things under discussion here. So, the IC things whose origin is clearly understood by us are things that only intelligent designers make. Neodarwinists, however, claim that IC structures in living things can be gotten without intelligent designers.

This creates (a) a presumption in favor of a design origin for IC structures, by simple induction, and (b) a burden for the neodarwinists to show, not just imagine, that you can get the IC structures without designers. The often-repeated accusations of ID critics that ID wants to "win by default" always strategically ignore the inductive knowledge base that we have about IC systems. But that knowledge base is precisely what serves as the basis for the claim that there is a prima facie low probability of getting IC without designers. That is, in the realm of IC systems whose origins are well understood, we don't see that happening.

I said that SETI is a search for signals that only an ETI could produce. Swan replies that I "fail[s] to acknowledge that SETI's protocols depend on knowledge of how we send signals and extension to how we know that we might send signals. If an ETI has so fundamentally a different point of view that it sends a signal that we do not recognize as 'signal,' then SETI will likely fail to detect that signal." I don't fail to acknowledge that at all. It's irrelevant to my argument. I don't claim that it's impossible that there could be signals from ETI that SETI might fail to register. The assumptions made by SETI serve to narrow the search space somewhat, which is a reasonable thing to do. I don't claim that ID and SETI are exactly the same enterprise. Clearly they are not. My point is simply that the claim that in order to detect ID we have to have independent information about the designer is false, and SETI shows that to be the case.

Swan, in fact, concedes, "True, [SETI] is the search for a signal from being that we do not know exist and to whose existence we cannot even assign a probability, but who are being about which we do assume something." That's fine. Assume away. Assumptions are not knowledge.

Swan writes, "As I noted before, ETIs COULD send a signal that exactly mimicked the radiations from their own star -- in such a case, we might receive their signal but be unable to detect it." Yes, this shows that the claim that ETIs exist is not strongly falsifiable. Imagine that.

"Many of ID's claims look more like a hypothetical claim for SETI that it had detected a signal from an ETI civilization that acted like my hypothetical star-mimicking ETIs." Those ID claims that turn out to be in that category would have to be regarded as (weakly) falsified, just as analogous ETI claims would be.

-- Todd Moody, assoc. prof. of philosophy, St. Joseph's University (posted 2/11, 10:00 a.m., U.S. Eastern time)

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