Intelligent design rears its head

Intelligent design derives from an early-19th-century explanation of the natural world given by an English clergyman, William Paley. Paley was the populariser of the famous watchmaker analogy. If you found a watch in a field, he wrote in 1802, you would infer that so fine and intricate a mechanism could not have been produced by unplanned, unguided natural forces; it could have been made only by an intelligent being. This view—that the complexity of an organism is evidence for the existence of God—prevailed until 1859, when Charles Darwin's “Origin of Species” showed how natural selection could indeed “explain so many classes of facts” (as Darwin put it).

Proponents of intelligent design are renewing Paley's argument with a new gloss from molecular biology. Darwin himself acknowledged that “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” Intelligent designers claim that living things are full of such examples at the molecular level. Blood clotting is one: ten proteins have to work together in sequence for the process to occur. So-called eukaryotic cells, which digest nutrients or excrete waste, are another: these cells contain an elaborate “traffic system” which directs proteins to the right compartments.

In both cases, argues Michael Behe, whose book “Darwin's Black Box” is one of the bibles of intelligent design, you have complex systems that will work only if all the components operate at once. He argues that you could not get such a thing from “successive, slight modifications”. Hence the molecular machines inside living beings are evidence of an intelligent designer—God.

Intelligent design asks interesting questions about evolution, but since all its answers are usually “God”, scientists have rejected it. As the National Academy of Sciences has said, intelligent design “and other claims of supernatural intervention in the origin of life” are not science because their claims cannot be tested by experiment and propose no new hypotheses of their own. (Instead, intelligent designers poke holes in evolutionary theory.)

In addition, biologists point out that the intelligent designers' favourite examples of “irreducible complexity” often prove not to be. Some organisms, for example, use only six proteins to clot blood—irreducibility reduced. In other cases, single parts of a complex mechanism turn out to have useful functions of their own, meaning that the complex mechanism could have been produced by step-by-step evolution. When the Discovery Institute, a promoter of intelligent design, came up with a list of 370 people with science degrees who backed their ideas, the National Centre for Science Education responded with almost 600 scientists called Steve or Stephanie who rejected them.

Whichever way the argument over intelligent design is finally resolved, it is likely to damage science teaching. This is not because bad science standards will necessarily be adopted but because—as Diane Ravitch of the Brookings Institution showed in “The Language Police” in 2003—the biggest threat to high standards is the unwillingness of state Boards of Education to offend any sort of pressure group, whether right or left. Instead, they avoid controversial topics altogether. In 2000, a survey by the Fordham Foundation found that only ten states taught evolution fully, six did so skimpily and in 13 the treatment was considered useless or absent. (Kansas received an F minus, and “disgraceful”.) These failings shame American evolution teaching, and the manufactured controversy over intelligent design will do nothing to make them better.