The intelligent-design movement began at a conference of proponents and antagonists of Darwinian evolution at Baylor University in 1992, but the phrase didn’t enjoy wide circulation until it was taken up by the Discovery Institute in 1998 as a central tool in a five-year plan to challenge Darwin in the press, in the courts, and in the schools.

Simply and sympathetically defined, intelligent design asserts that the biochemical systems that make life possible are simply too complex to have evolved from nonliving matter in the mere 4 billion years or so since the Earth formed. Furthermore, the structure and operation of these systems exhibit all the hallmarks of design—of being consciously configured to carry out their tasks.

Moreover, many of these systems appear to be irreducibly complex, composed of subsystems that are themselves complex but which perform no useful function on their own. Gradual, step-by-step Darwinian evolution proceeds by natural selection, the constant culling from generation to generation of minor genetic variations that allows more adaptive variations to multiply through populations at the expense of less-effective ones. But if a particular biochemical system has no function of its own, how can natural selection favor it over alternative structures? And even if several systems do have independent functions, how can natural selection facilitate them coming together to perform a function quite different from that performed by any one singly? Natural selection can’t favorably select for a molecule or system that doesn’t yet exist.

The idea that a dispassionate human observer can see signs of deliberate design in the lineaments of nature is not new. The Christian apologist William Paley (1743–1805) argued eloquently that the hand of God is manifest in all of creation. The novelty of intelligent design is that its creators decline to give a name to the designer whose work they see and assert that the positive evidence of design is as diagnostic of the failure of Darwinism as the self-confessed inability of evolutionary biologists, after decades of intensive research, to account for any of the major systems supporting life on evolutionary grounds.