By Michael Behe
de-sign' (n) -- The purposeful or inventive arrangement of parts or details
Imagine that, while walking across a field one day, you struck your foot against a watch. Examining the watch, you notice that its many parts fit together precisely, and that they are so ordered as to point out the time of day. There is little doubt, as the Reverend William Paley argued in his 1802 classic Natural Theology, that you would be certain that the watch had been purposely designed. In fact, that is exactly how we recognize design -- when we see a number of intricate parts that appear arranged to accomplish a purpose.
Now imagine that, while walking across a biology laboratory one day, you spied an outboard motor. Examining the motor, you notice that its many parts fit together precisely, and that they are so ordered as to propel a vessel through liquid. There are some salient differences, however, between your experiences in the field and in the lab. One difference is that, unlike the watch, the motor is quite tiny (you need a microscope to see it) and is part of a living bacterial cell. Another difference is that the motor is actually more intricate than the watch. While the watch must be constructed by someone, the motor actually assembles itself -- all in all, a much more impressive system than the watch.
Is the cellular outboard motor the only example of intricate machinery in life? Not at all. In the past 50 years, science has shown that the cell, the foundation of life, is chockful of molecular machines -- literally, machines made out of molecules. For example, a special issue of the journal Cell spoke of "the protein machines that control replication, splicing ... the machines that underlie the workings of all living things." Hasn't the complex foundation of life been explained by random mutation and natural selection? No. As University of Chicago microbiologist James Shapiro remarked, "There are no detailed Darwinian accounts for the evolution of any fundamental biochemical or cellular system, only a variety of wishful speculations."
So, then, what do you conclude about that motor, that fragment of life? Was it, too, designed like the nonliving watch? In my 1996 book Darwin's Black Box: The Biochemical Challenge to Evolution
, I answered yes. Whenever we see a complex arrangement of parts that fulfills some identifiable function -- for example, the faces on Mount Rushmore, the meaningful dots and dashes of a message in Morse code, or the pieces of a sundial -- in our experience that indicates design. Now that we have found such intricate machinery in the cell, I argue we are rationally justified to conclude that it, too, was designed.
The argument for the intelligent design of parts of life is an example of inductive logic. Inductive logic is common in science, and involves the extrapolation from things we have experience of to something outside of our experience -- sometimes very far outside. A good example is the Big Bang theory. In the early part of the 20th century, most scientists thought that the universe was stable and eternal. However, new data showed that the galaxies were rushing away from the earth and from each other. From our experience with simple things such as firecrackers and cannonballs, we know that particles rush away from each other in the aftermath of an explosion. By inductive reasoning, some scientists proposed that perhaps the universe itself began in something akin to a giant explosion.
Besides inductive logic, Big Bang theory and intelligent design theory have something else in common -- they both strike some people as having unwelcome philosophical or even religious overtones. For example, in 1989 the editor of Nature, John Maddox, wrote an editorial entitled "Down with the Big Bang," in which he called the theory "philosophically unacceptable." The eminent German chemist Walther Nernst in the 1930s said that, by definition, science required an eternal universe, so according to Nernst, the Big Bang theory was not science. But despite its philosophical overtones, even when it was first proposed, the Big Bang was a strictly scientific theory because it relied entirely on physical evidence and logic. I view the intelligent design hypothesis for molecular machinery in the same light. Although the idea may have philosophical overtones, it is based entirely on physical evidence and logic, and so is a scientific idea. Science should not shy away from an idea because of philosophical jitters.
Michael Behe is a professor of biochemistry. He is the author of
Darwin's Black Box and has been one of the leading proponents for intelligent design. In October 2005, he testified as an expert witness for the defense in the landmark trial in Harrisburg, Pa., stemming from the Dover Area School District's decision to introduce intelligent design in the high school science curriculum.
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