Dumbing down intelligent design
'No practical biologist interested in sexual reproduction would be led to work out the detailed consequences experienced by organisms having three or more sexes; yet what else should he do if he wishes to understand why sexes are, in fact always two?' -- R. A. Fisher (1930).
The scientific definition of "theory" is very different from its popular meaning of "wild speculation." The Theory of Evolution, like the Germ Theory of Disease, or the Atomic Theory that forms the foundation of chemistry, is solidly based in observations and experiments. The "theoretical" part, in each case, is a collection of well-tested principles that make sense of the masses of data and let us make predictions. For example, Germ Theory led to measures to limit the spread of AIDS, where the Divine Punishment Theory failed. The Theory of Evolution has been equally successful, with slowing the spread of insecticide resistance in insect pests among its recent contributions.
But is there a place for speculation in biology? I think there is, so long as we don't confuse it with fact or well-grounded theory. For example, life as we know it uses nucleic acids for heredity and makes much of its cellular machinery from proteins, but can we think of other possibilities? If so, can we design experiments that would detect such alien lifeforms, if they exist, on Mars or perhaps even on Earth?
Similarly, what if some alien life-form -- any sufficiently advanced life-form is indistinguishable from a god -- has intervened in evolution here on earth? Could we develop quantitative methods to measure this effect, as we now do for natural selection and gene flow? Or, suppose we had an old bloodstain purported to be from a demigod; could we extract DNA, look for alleles that don't match anything in the human genome, and (if we found any) clone them into E. coli? A gene for smiting might have military applications. Perhaps others could be reverse-engineered for flood control. (Hey, mixing religion and science was their idea, not mine!)
The topics in the last paragraph may be too speculative to be competitive for tax-supported research grants -- success rates for many NSF programs are around 10% -- but private foundations could certainly fund such research, if they chose. To be taken seriously, however, researchers looking for evidence of intelligent design would need, as in all of science, to design experiments that have the potential to disprove their hypotheses, if those hypotheses turn out to be wrong. And they would need to publish their results in peer-reviewed journals, so that other scientists have a chance to catch any logical fallacies or methodological problems they may have missed.
This is what the advocates of intelligent design have failed to do. Put all the intelligent design papers ever published in a pile and you don't match the productivity of one good graduate student. Whining, as in the much-discussed film, Expelled, is no substitute for science.