As has been noted by many, Darwin's world-changing *The Origin of Species* was a cluster of intertwined arguments in favor of some such proposition as that mere animals are the product of evolution by mutation and natural selection. Human persons aren't mere animals, as Aristotle observed:

they are *rational* animals (at least). Are *they* too the product of evolution? Darwin produced a second cluster of arguments in support of an affirmative answer to this question; it was articulated in his second thick book: *Descent of Man*. *Descent* was intended to address arguments from the co-discoverer of the theory of evolution by mutation and natural selection (Alfred Wallace, arguably the man who made the discovery *before* Darwin) to the effect that the cognitive powers of the human mind are too great to have been produced by the lowly dual-mechanism of mutation and natural selection.

An argument is a chain of reasoning from premises to a conclusion; the links in the chain are inferences. If the argument is sound, the premises are true, and the inferences are sanctioned by logic, which is the science of reasoning. The purpose of this talk is to partially report the result of my subjecting Darwin's arguments in *Descent* to scrutiny from the perspective of logic. Unfortunately, this scrutiny reveals that Darwin (like many of those who have sought to extend and modernize the arguments of *Descent*; e.g., Steven Pinker and Gary Marcus) was quite illogical.

Background reading:

Bringsjord, S. (2001) "Are We Evolved Computers? A Critical Review of Steven Pinker's *How the Mind Works*" *Philosophical Psychology* 14.2:

227-243. Offprint at http://kryten.mm.rpi.edu/selmer.wallaceparadox.pdf.