Oh, pity these thinkers! For they were writing before armies of social scientists learned to coax subjects into rooms with half-silvered mirrors and into high-tech brain-scanning machines, generating reams of data on what people are "really" like.

But would any of this have changed our dead philosophers' minds about human nature? After all, the evidence remains decidedly mixed -- at best, we are a wondrously complicated mess of contradictions and stunningly silly tendencies. And one of those silly tendencies is the "confirmation bias" -- that is, people tend to believe only the evidence that confirms what they already think.

Such is the pleasure and frustration of the new book "The Mind of the Market: Compassionate Apes, Competitive Humans, and Other Tales From Evolutionary Economics." On one hand, we have author Michael Shermer, founder and director of the Skeptics Society, captivating raconteur of all the greatest hits of behavioral, evolutionary and neuropsychology, provider of wonderful cocktail party material, like the one about 50% of an audience challenged to count the number of completed basketball passes failing to notice the gorilla walking across the crowded court. But we also have Shermer, the tendentious libertarian, doing logical back-flips unbecoming a self-proclaimed skeptic to marshal human nature's unruly contradictions into a political program of minimal government and extreme market capitalism.