quote: That is not my understanding of Behe's position. IMO, Behe suggests that it is implausible for an IC system to evolve because it would have to involve a circuitous, indirect Darwinian pathway which is much more improbable than a "direct" Darwinian pathway consisting of gradual improvements on a basic function.
That was his argument, in the days of Darwin's Black Box but I don't think it's his argument now. I think his argument now is that some evolutionary changes require simultaneous mutations (at least two specific mutations) and are too improbable to occur without assistance. The problem with this is showing that the mutations must be simultaneous and I don't think that there are any proven examples yet.
The argument you give above has some serious problems. While the direct pathway might be the simplest means of obtaining a specific result that's really thinking of evolution as working like an intelligent designer - seeking the best way to get to a pre-specified goal. It seems to me more likely that evolution will often follow "indirect" routes because it is NOT goal directed. Looking with hindsight on the probability of the path actually followed is likely no more useful than looking with hindsight on the result of the lottery. And if evolution follows indirect paths we should expect it to reach solutions which can only be found by following indirect paths.
quote: Behe acknowledges that if a function requires two specific mutations - each of which are, in themselves, non-adaptive - such a function can evolve. Chloroquine resistance is an example of this, according to him.
But isn't it true that he considers it extremely unlikely, and that this is the heart of his case ?
quote: Umm, I'm not making any argument regarding irreducible complexity. I was merely stating what Behe's position on irreducible complexity is. I wasn't saying that I agree with him.
But does Behe still believe it ? Is it still his position ? At one point he had the idea of changing the definition of irreducible complexity completely, and his more recent argument seems a development of that. Certainly that gives me the impression that his thinking on the matter has changed - and he never had a solid argument against indirect routes in the first place.
quote: Behe considers the evolution of a function that requires two individually non-adaptive mutations to be implausible for primates
So, in fact, you were doing a rather poor job of clarifying his position by making a blanket claim that he believed that such functions could evolve. Wouldn't it have been better to clarify the population issue at the start ?
quote: I really am not quite sure what Behe's current stand on the issue of irreducible complexity is. However, on the surface at least, it seems that it's less probable for an IC system to evolve than for a non-IC system to evolve.
If you aren't sure of his position then you can't really clarify what it is, can you?
As for your other assertion, the relative probability of evolving a specific function by a specific direct route versus a specific indirect route would seem to be completely irrelevant - even if we do not consider the fact that evolution has no preference for direct over indirect routes.
quote: Behe would argue that four simultaneous mutations is too implausible - even for viruses and bacteria. This study does not report that all four mutations must arise simultaneously in order to confer a selective advantage. Indeed, it could be that each mutation conferred some selective advantage.
So why not concentrate on that rather than arguing about the number of simultaneous mutations that Behe allows (and managing to miss the point that it is numbers - population size - that are the most important issue)
quote: If I understand Trixie's main point correctly, then it is that ID proponents hold that the evolution of OmpF is extremely implausible because several mutations would be required before any selective advantage appears. Possibly, we're not communicating very well, though.
That's the problem when you ignore the context. You fail to understand the points being made. The point here is that your "clarification" of Behe's views on IC systems, assumed that Behe still held to the views in Darwin's Black Box . But it is far from clear that that is true, given that Edge of Evolution seems to derive from a radical redefinition of IC that Behe suggested (which in itself indicates that Behe realised that his original argument was in trouble).
quote: I have absolutely no problem with concentrating on the implications of the study reported by Trixie, except that it'd be a touch superfluous since I don't think I could do better than Wounded King in explaining why multiple simultaneous mutations are not needed for the OmpF function to evolve in these phages.
So the only bit of your posts that might be useful has already been done better. Why post at all in that case ?
quote: I suspect that you have not read EofE. In that book, Behe only mentioned irreducible complexity en passant
Unless Behe indicated that he still held to the views expressed in Darwin's Black Box that is irrelevant - since that is the point we are discussing, as I keep pointing out. And you have already admitted that you do not know if Behe still holds to that position or not, so I fail to see why you can't simply agree that you were wrong to try to "clarify" his position on IC and leave it at that.
I begin to think that the "communications problem" you referred to is the failure of your continual attempts to change the subject.
That is not my understanding of Behe's position. IMO, Behe suggests that it is implausible for an IC system to evolve because it would have to involve a circuitous, indirect Darwinian pathway which is much more improbable than a "direct" Darwinian pathway consisting of gradual improvements on a basic function.