An excellent physical (not philosophical) rebuttal of Behe’s mousetrap analogy.
A reducibly complex mousetrap
Creationist Michael Behe has been attracting a lot of attention recently with his advocacy of the “intelligent design” argument. He makes the claim that certain biochemical processes are “irreducibly complex”: they involve multiple proteins, and removing any one of them would destroy the function of the overall pathway. From this he concludes that these pathways could not have evolved through the action of natural selection, but instead must have been created by an “intelligent designer.”
To illustrate the concept of irreducibly complexity, Behe uses the common snap mousetrap. “If any one of the components of the mousetrap (the base, hammer, spring, catch, or holding bar) is removed, then the trap does not function. In other words, the simple little mousetrap has no ability to trap a mouse until several separate parts are all assembled. Because the mousetrap is necessarily composed of several parts, it is irreducibly complex.” (Behe, 1996).
It is not my purpose here to point out all of the philosophical flaws in Behe’s argument; this has been done thoroughly in many of the resources collected on John Catalano’s excellent web page. Instead, I wish to point out that the mousetrap that Behe uses as an analogy CAN be reduced in complexity and still function as a mousetrap. The mousetrap illustrates one of the fundamental flaws in the intelligent design argument: the fact that one person can’t imagine something doesn’t mean it is impossible, it may just mean that the person has a limited imagination. Behe’s evidence that biochemical pathways are intelligently designed is that Behe can’t imagine how they could function without all of their parts, but given how easy it is to reduce the complexity of a mousetrap, I’m not convinced. (Of course, the reduced-complexity mousetraps shown below are intended to point out one of the logical flaws in the intelligent design argument; they’re not intended as an analogy of how evolution works.)