I’m moving this up from the comments on an earlier post as I think it will take more that a comment to respond to.

A commenter, Josh Caleb, says that he has “a few honest questions“. I am going to answer him as if that were true even though I am now somewhat suspect that it isn’t due to his having cited trueorigins.org, an antievolution knockoff of talkorigins.org, and because of several of his comments left in response to others.

Caleb: What predictions does Darwinism make that ID can’t make?

Setting your use of the outdated term “Darwinism” aside, I’d say none. That is one of the problems with “God did it” explanations. An all powerful supernatural intelligent designer like the one posited (their disingenuous protestations regarding the possibility of extraterrestrials not withstanding) by ID creationists can do anything, in any way it chooses including make things look like they evolved through completely natural processes. And an explanation that can fit any possible set of observations doesn’t really explain anything, it just relabels our ignorance.

Caleb: If we start with the real observations of: 1) Descent with modification, 2) Random Mutation, 3) Natural Selection, 4) Homology of Morphological Features and Genetic material (DNA) between species… What does “common descent” (i.e. Darwinism) predict that ID does not?

The mere positing of a all powerful supernatural designer doesn’t really predict anything about any of these things. God doesn’t have to use descent with modification, but he could. God doesn’t have to use mutation or selection, but he could. God doesn’t have to make organisms with homologies, but he could. Do you see the problem?

What usually happens here, and the pre-Darwin creationist scientists did the same sort of thing, is that creationists import their own personal beliefs or beliefs culled from some preexisting theology, about what God would or would not do. But these are not obvious or natural predictions of what a supernatural creator/designer must or will do, they are theological rationalizations of what is already known.

Gazelles can run fast, why? Because the Lord in his wisdom and mercy knew that they would need to be able to escape their predators and made them fast runners.

We know that Gazelles are fast runners from direct and repeatable observation, likewise we know that they have predators, and the recognition that the ability to run fast might be helpful in escaping them seems to be an obvious thing. But all that stuff about the Lords supposed mercy, wisdom, and knowledge is pure assertion. A matter of faith not testable by reference to any experiment or observation of the natural world, and it therefore fails utterly as a scientific explanation.

Let’s take homologies as an example since you mentioned them. Creationists often dismiss homologies as being evidence of common descent and argue instead that they are the product of common design. Example:

An evolutionist looks at homology and can only see descent from a common ancestor with modification. …Homology bears the strong signature of an intelligent designer. It is creation from a common design that has produced homologous structures. (Source: Homology: A Problem, not a Proof, for Evolution, Jon A. Covey)

But the difference is common descent with modification (evolution) demands that we will find modifications of pre-existing structures in living things. With design it can go either way. A designer can modify something they, or another designer, has already made, or they can start from scratch with a radically different approach.

So in this case the hypothesis of evolution makes an absolute prediction that we should observe in living things structures that appear to be modifications of similar structures in other living things (homologies). That is a testable prediction because if he do not find homologies that will tend to falsify the hypothesis rather than be consistent with it (note I didn’t say “prove it”).

Design on the other hand makes no testable prediction either way, which means whatever we observe in this case it won’t make any difference.

Multiply this example by pretty much everything about life on Earth and it adds up very quickly.

Of course modern ID creationists don’t merely make untestable assertions about things being designed, they marry these to a negative argument. That being, that this or that feature found in living things is not, or cannot be, explained by evolutionary theory, therefore it must have been “designed” (created Ex nihilo, or manipulated in some way, they never say how, because they can’t) by a supernatural designer. But unfortunately “evolutionary explanations are no good” does not count as a positive prediction for ID. This is why I often say the ID creationism can be succinctly stated thusly:

Evolution sucks, therefore God did it.

Caleb: If ID is not falsifiable, why did Ken Miller spend all that time attempting to show how the flagellum is not irreducibly complex? Doesn’t Miller’s attempt at falsification prove that it IS falsifiable (even if Miller didn’t quite get it right and failed in the attempt as Behe has gone on to demonstrate…) ?

Demonstrating that the flagellum is not truly irreducibly complex; that it could in fact have arisen in a step wise manner that evolution requires, would not falsify ID. It would only falsify the argument that the flagellum is irreducibly complex in that manner. In other words Miller is attacking the “evolution sucks” part of ID, the “therefore God did it” part remains untestable.