Last night, C-SPAN broadcast a lively debate on whether intelligent design should be taught in schools, sponsored by the American Enterprise Institute for Public Policy Research. Click here for a description of the event. C-SPAN archived the video in three parts.

A telling exchange occurred between Kenneth Miller and Paul Nelson over the flagellum, a tail bacteria use to propel themselves through fluid. Proponents of intelligent design have argued that since the parts of the flagellum have no function that could possibly confer evolutionary advantage, the whole flagellum could not possibly have evolved from parts.

Miller showed that even with 80% of its parts removed, the remaining parts have quite a useful function. Hence, it is eminently possible that the parts evolved for a variety of purposes and were then combined for an entirely new purpose.

Nelson’s response was that the flagellum’s function is to propel the bacterium through its medium, and the parts have no ability to propel. He implied that, therefore, the flagellum could not have evolved from parts.

Nelson’s argument against evolution reminded me of Searle’s argument against artificial intelligence. Both are deeply flawed and reminiscent of the idea of the homunculus. This is the childish notion that our intelligence comes from a smaller, whole person inside each of us–the homunculus–who controls the larger body. The notion leads to the question: where does the intelligence of the homunculus come from? Of course, examination of the interiors of bodies reveals that they possess complex organs, but no homunculus. So, the notion is dismissed and we are led to more useful threads of inquiry regarding how bodily behaviors might be controlled by the organs inside them.

Similarly, Nelson suggests that we look for propellant ability in the deconstruction of the flagellum. Not finding this ability in the flagellum’s parts, he concludes that the flagellum must be the product of design.

Nelson displays ignorance, in this exchange, of the well-understood idea of emergent properties. Propellant ability arises out of a specific combination of more fundamental parts, which individually have no propellant ability but are useful and functional nonetheless.