Ever since President Bush advocated that the intelligent design critique of Darwinism be allowed in public schools, a riot of public pronouncements has condemned the design perspective as retrograde, unscientific and downright ominous.

A number of logical fallacies are routinely employed in efforts to debunk intelligent design. In such cases, intelligent design is criticized and dismissed on the basis of an argument that is illogical and therefore false. One need not be an expert in Darwinian biology to sniff out these basic blunders. In this brief space I will note just one: the straw man argument.

In the straw man argument a position is made to look ridiculous and then the caricature is knocked down. Intelligent design is repeatedly presented as a plan to institute religious and unscientific dogma in the public schools. The facts, however, speak otherwise. Intelligent design's think tank, The Discovery Institute, says this: "The theory of intelligent design holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." The controlling premise is the effort to discern the best explanation for a natural phenomenon, given the available empirical evidence: a fundamental precept of scientific investigation. Unlike creationism, intelligent design makes no appeal to religious texts, but invokes empirical evidence, as well as the principles of design detection, which are already used in sciences such as cryptography, archaeology, forensics, and in the search for extraterrestrial intelligence.

Mathematician and philosopher William Dembski argues that certain features of the natural world exhibit patterns that are best explained on the basis of design (or intelligent causes), rather than on the basis of mindless nature (or unintelligent causes).

For example, even if we didn't know from history that an eccentric artist was responsible, we would identify the presidential faces carved into Mount Rushmore as designed because natural patterns of erosion cannot explain them. The complexity of the phenomenon fits a specifiable pattern: the faces of the presidents, which we recognize from other sources. Similarly, archaeologists distinguish ancient artifacts from naturally occurring objects on the basis of design detection. The complexity discovered in certain objects fits a specifiable pattern indicating that intelligent causation was at work.

Intelligent design proponents argue that some organisms indicate specified complexity, and that these organisms are better explained by intelligent causes than by natural law and chance alone. The DNA code is an example of specified complexity. It contains a language that is not reducible to the laws of chemistry and physics, which do not specify its content. The odds against all the factors required for DNA to come together through the operations of mere matter and chance are vanishingly small.

Similarly, biochemist Michael Behe argues in Darwin's Black Box that certain molecular machines are irreducibly complex, which means that all of its basic parts are required for its function, as with a mousetrap. The bacterial flagellum, for example, is a highly complex outboard motor attached to a bacterium. A gradual process of mere chance and natural law is insufficient to explain this irreducible complexity, Behe argues, since the motor function could not exist in evolutionary predecessors that lacked any of the many necessary parts.

However, Darwinists insist that intelligent design invokes God to cover ignorance of natural processes. This is exactly wrong. The design inference is not based on ignorance, but on increased knowledge of the microscopic realm and on the well-established principles of design detection. When Darwinists refuse to admit intelligent cause as a possible explanation for specified complexity, this only reveals that they define science such that intelligent causes are disallowed in principle. But this approach is not a discovery of science itself. It is rather a philosophical commitment to materialism (the belief that reality is reducible to impersonal physical laws).

May these few considerations spur readers to assess rationally intelligent design's actual arguments and to avoid the logical fallacies so often employed in place of intelligent thought about life's origins.

Douglas Groothuis is professor of philosophy at Denver Seminary.