The Problem with Christians

[Esquilax]

I think that you are rephrasing the points to make your case.  If I rephrase your arguments, to "I can't see how this evidence could happen without evolution..." would that mean that the case for evolution is nothing but negative arguments?

I'm not rephrasing anything, and you couldn't do that with my arguments either. Do I really have to show you the difference between a positive and negative evidence?

The key claim at the core of irreducible complexity is that certain biological forms are irreducibly complex, I don't think I'm being controversial in thinking that, yes? But that claim is fundamentally negative in nature, it's solely a suggestion that the claimant cannot think of a way that a given form could have evolved, and has therefore concluded that it could not happen: they cannot find a way to reduce the components without robbing the organism of its function, so there must not be a way for that to happen. That's the lynchpin of irreducible complexity as an argument, there is no argument without it, and the sole purpose of that lynchpin is to take evolution off the table as an answer to the question. In this way, it is a negative argument.

Meanwhile, take my piece on Samotherium, for example. I was asked how I could determine that the fossil Samotherium was related to modern day giraffes, and what I sought to do was not just eliminate all the other options, which would have constituted a negative argument. Starting with a simple basis, that genetic similarity tends to correlate with morphological similarity, and that genetic similarity is also an indicator of two organisms being related, I constructed a case for the idea that the two were related: we have a modern short-necked giraffid species with which to make a comparison of neck bones, and if we compare all three, what we find is perfect similarity (down to the angle the vertebrae sit at) with both short and long-necked giraffids in the lower vertebrae, and at the higher vertebrae we find a similarity only between Samotherium and modern giraffes, which is what we'd expect because obviously the short-necked animal wouldn't have the longer neck bones. Establishing a remarkably identical morphological profile allows us to conclude a genetic similarity due to the previously established gene/morphology connection, and that is how we reasonably conclude that Samotherium is a relative of the giraffe. This is what a positive argument looks like: it's a case building toward one conclusion, and not away from the alternative.

Now, yes, by definition a positive case will also lead one away from the alternatives, but what matters is how you get there, not where you get to. It's like if you're on a road leading to destination A and destination B, and what I'm talking about here is the difference between traveling to destination A because that's where you're going, and ending up in destination B simply because you're reversing away from A. If you end up in B because of the latter motivation, did you really end up in B because of a reasonable, conscious conclusion on your part?

 It seems to me, that when you make a positive case for one thing, then you are necessarily excluding other alternatives.  The criticism of a purely negative argument is that you are assuming your position, by negating the opposing position.  You are not given positive reasons to connect the evidence to your position.

So where is the positive evidence in irreducible complexity?

 If there are only two options, then this is legitimate, if there are other options, then it is not.

And how did you determine there were only two options?

We can get into the claims of complex specified information, and irreducible complexity.  I think that your statement that in every instance an answer has been found is overstated.  But; again, I don't want to go into too many directions at once (nothing really get's discussed then).

I think the larger issue is that, even if we have an example of supposed irreducible complexity that doesn't currently have an evolutionary response, all you're left with is an argument from ignorance that there isn't an evolutionary response, so irreducible complexity wins by default. That's sort of the problem with all of this: in a world without responses to your ID arguments, you're still left with no positive evidence indicating ID, just problems with evolution.