A few days ago I read a thought-provoking post by Chicago Law’s Albert Alschuler, who takes Intelligent Design more seriously than I’d expected from, well, anyone worth taking seriously. A few reactions:
1. Like Alschuler, I’m troubled by the simplistic Popperian tone adopted by many ID opponents. The glib anti-ID position seems to be, “Science means falsifiability, and ID is not falsifiable, therefore it ain’t science.” Quick – how would you falsify the theory of evolution? Evolution, in its broadest sense, has long struck me as not terribly susceptible to falsification. In Kuhnian terms, evolution is best understood not as a theory, but as a paradigm – an organizing set of principles that makes sense of much existing data and generates more specific (lower-level) theories. These more specific theories may be subject to some form of falsification; for instance, the theory that birds evolved from dinosaurs could potentially be falsified by discoveries in the fossil record of organisms midway between mammals and birds. But that discovery wouldn’t threaten the notion of evolution itself, merely on one dispensable piece of the story. The overarching evolutionary concept would simply adjust to incorporate this new bit of data. Biologists implicitly admit that evolution is a paradigm, rather than a falsifiable theory, when they say that evolution is the fundamental explanatory principle of their discipline.
2. To continue the Kuhnian account, ID proponents presumably wish to foment a scientific revolution – that is, to overthrow the existing paradigm. Here is where I think ID’s weakness really shows. A scientific revolution has two major components: (a) an accumulation of internal contradictions within the accepted paradigm or evidence that cannot be explained within it; and (b) a viable successor paradigm. The ID theorists claim to have met criterion (a), but they really haven’t. Many of the alleged defects of evolutionary theory are hackneyed objections originally raised by creationists (now reborn as ID theorists) and already demolished, such as the tired claim that complex eyeballs had to emerge all at once because a partial eyeball is worthless. ID also purports to point out phenomena that evolution hasn't yet explained; but this doesn't satisfy criterion (a) if the unexplained phenomena can in principle be explained within the existing paradigm with the appropriate data (e.g., new fossil evidence). Indeed, the fact that a paradigm continues to generate interesting research questions is a sign of its vitality. In any case, there are assuredly biological mysteries that remain, but evolution both generates and dispatches such mysteries. For there to be an accumulation of anomalies, the new mysteries would have to mount faster than the old ones are solved. That’s manifestly not the case here.
But even if you think criterion (a) is met, criterion (b) clearly is not. ID does not constitute a viable paradigm of its own, because ID advocates have failed to do anything except try to build up the case for (a). ID is essentially the absence of a paradigm; it is defined almost entirely by doubts about the existing paradigm rather than a new framework of its own. As at least one commenter on Alschuler’s post noted, the case for ID rests on a false dichotomy in which either evolution is correct or there must be a designing intelligence. If only two options are considered, then eliminating one means accepting the other. But other options exist – for instance, that Earth was seeded by life from another planet. I don’t know of any good evidence for that proposition, but then again, I don’t know of any good evidence for the existence of an intelligent designer, either. In order for ID to become a proper candidate for a replacement paradigm, it needs something more: the ability to generate positive propositions that create the basis for ongoing scientific research.
3. But maybe ID does produce propositions that could provide the basis for ongoing research. At least, maybe some version of ID does. For instance, if the Intelligent Designer really cared about efficient design, then he (it?) wouldn’t include “junk” DNA in organisms’ genomes; nor would he maintain the DNA for vestigial organs. The problem with this version of ID, as Robert McNamara observes, is that it’s demonstrably false: junk DNA and vestigial organs are quite real. If ID in this form held the throne of accepted paradigm, it would be ousted rather quickly in favor of some more satisfactory paradigm – like, say, evolution. To inure themselves from this devastating criticism, ID proponents must retreat into a much vaguer version in which the Intelligent Designer has inscrutable preferences that might or might not include a concern for efficiency. But at that point, ID ceases to be interesting as a source of research propositions. (Just to be clear, the evolutionary paradigm also uses vagueness to insulate itself from falsification, as indicated in point (1) above. The difference is that it nonetheless generates interesting and research-worthy lower-level theories, which ID has not yet done.)
4. ID survives by trading on its ambiguity. ID has different meanings for different speakers and listeners. For some, ID is just code for creationism – clever code, because it might just allow ID to slip into some public school curricula. That ID is thoroughly inconsistent with another ID, as described by some of its leading advocates, which allegedly accepts the role of genetics, heritability, and natural selection, but posits a “guiding hand” that pushed mutations in the right direction, gave a boost to certain biological forms, etc. Notice that this latter form of ID is essentially indistinguishable (by evidence) from your regular hands-free evolution. Why? Evolution relies on random events. The fossil record cannot reveal the probability distribution that governed those events; it can only show the actual outcomes. As a result, we cannot know whether any particular event, like an improbable but highly beneficial mutation, really just happened randomly or because Someone gave it a nudge. So this evolution-with-a-little-help kind of ID can slide by as an alternate version of the standard evolutionary story. The problem is that this ID is like the slightly odd coworker you generously invited to your Christmas party, not realizing that he would bring along all his creepy friends. If you let this ID theory in your schools, you’ll get all the less savory ID theories, too.