When Adam Smith wrote that butchers, brewers and bakers worked efficiently out of ``regard for their own interest,'' he was doing more than asserting that self-interest could be good. He was also asserting that self-interest -- a long-lasting, fact-based, explicit sense of ``what's good for me'' -- is possible. His Enlightenment-era model of the mind helped spawn Rational Economic Man, that being who is supposed to consciously and consistently perceive his own needs and wants, relate those to possible actions, reason his way through the options, and then act according to those calculations.

Rational Economic Man has taken quite an intellectual beating since certain financial events that I don't need to rehearse here. But it (it's not really a he, is it?) remains the basis for all the important institutions of society, from courts (where we assume that judges and juries can think ``objectively'' about a case) to medicine (where people are supposed to choose clearly among scientifically-tested options for treatment to elections (where voters are presumed to be weighing ``the issues'' and picking the candidate who best fits their interests. It is because we are supposed to be rational that governments guarantee our human rights: To be enlightened, Immanuel Kant explained, one must ``use one's understanding without guidance,'' and this is impossible without freedom of speech and of thought. The presumption that we're rational -- at least when we're at our best and most human -- is the glue that holds global society together.

That's probably why we 21st-century people have such respect for science (so important in our culture that even people who hate science's version of the world feel obligated to use its language, referring not to ``creation'' but ``creation science'' when they want to deny evolution). Science is, after all, the ultimate collection of methods for creating knowledge by rational means.

It's ironic, then -- historically, colossally ironic -- that science is killing off Rational Economic Man. But it is: The data comes from ``hard'' sciences, from social science, and often from novel combinations of the two, like neuromarketing and neuroeconomics. Some of these fields are more rigorous and prestigious than others, but in they're all using the same fundamental method -- data-based, systematic, value-neutral -- to investigate the mind. And in evolutionary biology, cognitive science, social psychology, neurobiology, marketing studies, economics and many other disciplines, the scientific method is revealing that Rational Economic Man is indefensible, misguided and wrong.