In presenting the possibilities in this way, I may seem to be forcing words into the mouths of the intelligent designers. Their core position, after all, is that at crucial moments in the history of life, descendants of some ancestors who lacked some trait (or organ or structure) came to possess the pertinent trait (organ, structure) by some causal process that is, unlike natural selec- tion, intelligent. Why, then, do they have to talk about genes, mutations, and the need for protection against natural selection? The answer is that the traits in question are heritable—they are not introduced in each generation by some continued activity on the part of Intelligence, but emerge through the interactions of genes and environments. As in the case of the bacterial flagellum, there are underlying genes, and hence there have to be genetic changes in the passages from the ancestors to the descendants. If these changes occur over several generations, then, on the intelligent design-ers’ own principles, there has to be protection against the tendency of natural se- lection to weed out the hapless intermediates. If they happen in one step, then, again by the favored principles, there must be coordinated mutations. Hence, even if the position would prefer to talk more vaguely of “novelties,” it is committed to one of the options I have presented.
What intelligent design urgently needs if it’s going to make any progress in understanding these transitions, in tackling the problems it claims to raise, is a set of coherent principles that identify the ways in which Intelli- gence is directed and what its powers and limitations are. If we lapse from the official story for a moment, we have to have some idea about what In- telligence “wants to achieve” and what kinds of things “it can do to work toward what it wants.” What basis do we have to think that Intelligence aims to remedy the plight of the flagellumless bacteria, who can’t evolve into bacteria-with-a-flagellum under natural selection? What basis is there to believe that Intelligence—or anything else, for that matter—can coordi- nate genetic changes or modify environments?
In fact, we need two distinct kinds of principles. First, there have to be principles that specify when Intelligence swings into action. Perhaps they will tell us that Intelligence operates when there are potentially advanta- geous complex traits that can’t evolve by natural selection. Second, there must be principles that explain what Intelligence does when it acts. Perhaps these will identify the sorts of genetic changes Intelligence can arrange, or the ways in which it can inhibit the normal operation of selection.
It is already clear that these principles will be hard to state precisely. For, if Intelligence has been waiting in the wings throughout the history of life, seizing opportunities as they arise, we know that there are all sorts of things it hasn’t done. Apparently Intelligence isn’t directed toward elimi- nating the junk from genomes or removing vestigial structures like the whale’s pelvis or generating radically new arrangements for mammalian forelimbs. It’s possible, of course, that although directed toward these ends, Intelligence is simply unable to bring them about. So any satisfactory prin- ciples must differentiate between the bacterial flagellum, blood-clotting cascade, and similar places where Intelligence shows its prowess, and the accumulated junk, vestigial structures, and genetic blunders, where it re- mains in abeyance. . . .