What would it take to disprove Intelligent Design?

Scientific theories differ from other belief systems in that they are testable; in other words, they can be disproved. Imagine reading, for instance, any of the following headlines:

  • “Modern Chicken Fossil Found Side By Side with Dinosaur Bones”
  • “Chimpanzee DNA Radically Different From Human”
  • “New Data Shows Earth Only 10,000 [or 100,000 or 10,000,000] Years Old”

What do you think would happen to the theory of Evolution if any of those things occurred (assuming, of course, that the observations were replicated and confirmed)? It would certainly have to be radically modified, and might have to be rejected entirely, because according to the theory it just can’t happen that chickens and dinosaurs ever co-existed. And if human and ape DNA were found to differ by more than a few percent it would be very difficult, if not impossible, to reconcile that with present-day views of how these creatures evolved (relatively recently, from a common ancestor). And if the earth were really “only” ten million years old (much less ten thousand!) there wouldn’t have been nearly enough time for living cells, much less human beings, to have evolved.

In contrast, can you think of any way to disprove the theory of Intelligent Design? I used to think I could. Why not, I thought, look for imperfections in the design, instances where certain creatures seem less than ideally designed for their purpose. (As it happens, there are many examples of such suboptimal design.) But that approach doesn’t work. All the inefficiencies can ever prove is that the designer “works in mysterious ways,” or has a different aesthetic from ours about such things. So what appear to be botched designs may tell us something about the designer but they do not discredit the theory of Intelligent Design itself.

Intelligent Design doesn’t make predictions–other than the trivial one that living creatures should look as though they were designed. But that’s not a prediction; it’s just an explanation for a set of observations. It’s kind of like saying “Lightning looks as though Thor is throwing thunderbolts at us, therefore that’s what it must be.”

The Thor model of lightning is unscientific not because it’s wrong but because it’s untestable. There is no way, short of looking around for Thor and not finding him (and he could, after all, be hiding somewhere), of checking out the theory. Like Intelligent Design, it makes no predictions and, therefore, cannot be disproved. In contrast, the theory that lightning is caused by electric currents, while considerably harder to understand and at first blush a lot less plausible than the Thor model, predicts, among other things, that if Benjamin Franklin flies that kite in a thunderstorm one more time he’s liable to get fried.

Science is all too often taught as though it were merely a collection of facts. What we should be teaching is the process by which we have come to trust those facts, what evidence backs them up, and, most important, what new information could get us to change our minds. We need to teach kids that the hallmark of every scientific theory is that in addition to explaining known data it makes predictions about data that hasn’t been seen yet. Which means that every scientific theory is in constant danger of being disproved if those predictions fail to come true.

Until the Intelligent Design proponents can point to some finding–anything!– that might in future cause them to revise or abandon their theory, that theory is no more scientific than the once widespread belief that the plague was God’s punishment for our sins. If we allow such theories to be treated as science we might as well go back to curing disease by whipping each other to atone for those sins.

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