Biologists have made a number of discoveries about evolution, including natural selection, common descent, genetics, and random mutation. None of these discoveries are controversial, not even among ID advocates (the sane ones anyway). Both IDists and evo-biologists have incorporated known facts about evolution, but neither makes specific predictions about the outcome of a particular experiment.

We can imagine two predictive, neo-Darwinian theories (call them T1 and T2) that predict different outcomes for the same particular study. For example, T1 might claim that rate of acceptance of mutations is environmental-stress-independent, while T2 claims that it was environmental-stress-dependent. So, while neo-Darwinism encompasses theories that agree on verified facts of biological evolution (T1 and T2 both predict common descent, etc.), those theories can be mutually inconsistent. Thus, neo-Darwinism is a class of mutually inconsistent theories that meet certain criteria (natural selection, common descent, etc.).

I think ID advocates are willing to accept the verified results of evolutionary biology. So, two theories of ID (call them D1 and D2) would both predict common descent (or they’ll be inconsistent with the data). However, D1 and D2 would differ in their claims about the rate of acceptance of mutations as a function of environmental stress (something measurable in a specific experiment). So, like neo-Darwinism, ID is a set which includes mutually exclusive theories that feature intelligent design.

Notice now that it is relatively straightforward for the neo-Darwinist to devise an actual, predictive theory. The biologist simply makes observations, then proposes a corresponding physical mechanism that predicts (using verifiable laws of physics and biochemistry) a specific outcome in an experimental test.

Yet the ID advocate runs into trouble. His designer isn’t just an intelligent agent with limitations. His designer is God. There’s no need nor advantage in God using the same technique twice. So, the ID advocate is reluctant to say that the designer preferred one technique over another (D1 vs. D2). Besides, making such a distinction means talking publicly about the designer, and the ID advocate knows he’ll be laughed out of the room if he starts talking theology. For this reason, no experimental prediction (choice of D1 over D2) ever gets made by the ID advocate.

In principle, ID could be predictive and scientific. It would need to take one known experimental result, then devise an intelligent design rationale that predicts the known result and an unknown one. ID advocates don’t do that.

The claim that naturalistic science will never explain a thing is not itself a scientific claim. Today, that is what ID is doing because it cannot devise any actual scientific theories of ID.

One more thing. The modern evolutionary synthesis isn’t just consistent with common descent, natural selection and so forth. The observed facts are pretty much the only possibility consistent with the synthesis. In contrast, there are an infinite number of possibilities consistent with ID. There was no need for God to have relied on common descent, mutation, natural selection and the like. ID does not explain the observations so far. ID is consistent with them, but does not explain them because ID does not generically predict them. Of the billions of possible ways of designing living things, God chose the one way that can be explained by the class of neo-Darwinian theories?

Neither ID nor neo-Darwinian evolution are scientific theories. They are classes of predictive scientific theories. The difference is that the class of evolutionary theories is not an empty set because there are predictive scientific theories that belong to the class of neo-Darwinian evolutionary theories (many of which have been verified). In contrast, there are no predictive scientific theories that belong to the ID class.

It turns out that science is not committed to the best explanation of the data and observations, but is instead committed to a philosophical worldview called naturalism.

Science is committed to the idea that an explanation has to be more than a restatement of the data one is trying to explain. ID makes no predictions, so it can only restate observations, not explain them.

The question we are answering is this: “What is X such that X predicts the observations?” You’re not answering this question because your X (God) predicts whatever we observe, no matter what we observe. You’re just restating the question.

It may seem like commonsense to you that you have an explanation, but it’s actually not sensible at all.

If you have some data points on a chart, an explanation is a curve that passes through the data points. A curve interpolates and extrapolates. It predicts.

However, what you are doing is drawing dots over the data points on your graph and claiming that you’ve explained the data. If you observe a new data point, it can never contradict any of the dots you’ve drawn so far. When you “explain” your data this way, you can never be wrong. If you subtract the observations from your conclusions, you’re not left with a discontinuous curve, you’re left with nothing at all.

Prediction is vital to science and vital to explanation in general. ID fails to make predictions because it fails to specify enough about the designer to make any. In principle, ID could be specific enough to do so, but when the designer is God, there’s a reluctance to say what the designer was constrained to do.