The Fifth Way of arguing for the existence of God, according to Thomas Aquinas, is taken from the fact that non-cognizant things act for a purpose. He believes that this shows that an intelligent being is directing things now to a goal. This argument is not an intelligent design argument inasmuch as it does not argue from the present existence of purposive activity in a thing to a previous event in which the thing so acting was engineered to act in that manner. Rather, Aquinas argues that the fact that a thing acts now to attain a goal implies that it is now being directed by an intelligent being toward that goal. To a contemporary reductionist, this argument must seem quaintly mistaken, for what passes as purposive activity is really a mechanical process. The sunflower's turning toward the sun is the result of the flower's components acting essentially like levers in a machine. The same is true for all other things, both living and non-living. One...