My letter responding to George Will’s “A Debate That Does Not End” appears in the July 18 print edition of Newsweek.

George Will says the theory of intelligent design isn’t falsifiable—isn’t “a testable hypothesis.” Actually, particular design arguments are falsifiable. Design theorist Michael Behe, for instance, argues that we can detect design in the bacterial flagellum because the tiny motor needs all of its parts to function at all. That’s a problem for Darwinian evolution, which builds novel form one tiny functional mutation at a time. How to falsify Behe’s argument? Provide a detailed evolutionary pathway from simple ancestor to present motor. The flagellum might still be designed, but Behe’s argument that such design is detectable would have been falsified.

For a more in-depth discussion, see philosopher of science Stephen Meyer’s analysis of observability and testability here.