Attacks on Intelligent Design often charge that the theory is "unfalsifiable" and thus unscientific. Aside from the fact that this is simply incorrect--ID does put forth a falsifiable hypothesis (see William Dembski's explanatory filter, for example)--it is yet another area in which Darwinian theory actually fails the very test it would impose on everyone else.
If ever a "scientific" theory was unfalsifiable, Darwinian evolution is it. Think about it. Using the most popular current definition of "science," Darwinian macroevolution cannot be proved false.
As you’ll recall, the judge in the Dover ID case ruled (and it has been argued here by some commenters) that science by definition must be naturalistic. Naturalism assumes (note that it doesn't, nor can it, prove; rather, it assumes) that the physical world is all that is real, and thus all phenomena can be explained in terms of natural causes and laws.
Once this is assumed, there is no evidence that can disprove Darwinian macroevolution. Something like Darwinian evolution has to be true, because we are at that point dealing with two "facts":
1). There is a great deal of diversity and complexity among living things
2). That diversity and complexity has to have arisen by blind, purposeless, naturalistic chance
Any evidence which would seem contrary to the notion that all the diversity and complexity of life arose naturally and purposelessly must be reinterpreted, discounted, or completely put aside because we’ve already decided that "science" demands that it arose and diversified naturally and purposelessly.
This is how we end up with statements like the one I previously cited from the atheistic Darwinist Richard Dawkins (who is a passionate opponent of ID, I might add): "Biology is the study of complicated things which give the appearance of having been designed for a purpose."
Dawkins concludes, of course, that this is merely an illusion, because it has been decided at the outset that these complicated things have to have arisen by blind, purposeless, naturalistic chance. Evidence which would seem to falsify this cannot be what it seems to be, because we’ve decided a priori that all life must be explained naturalistically.
This is, of course, perfectly circular. It goes something like this: we know that all life arose and diversified through blind natural processes, so Darwinian evolution is true. And we know that Darwinian evolution is true because life arose and diversified through blind, natural processes. Since it reasons in a circle, it cannot be falsified. Yet the evolutionist attacks ID because it's supposedly unfalsifiable. So why does the evolutionist have the right to violate his own standard while ruling everyone else out of court on the grounds they violate it?