Last year, Bryan Caplan, Professor of Economics at George Mason University, blogger for EconLog delivered this talk, based on his book The Myth of the Rational Voter (named "the best political book of the year" by the New York Times.
I would strongly encourage everyone to take the hour needed to watch this through to its completion. It is a terribly depressing talk, but one I strongly encourage everyone to take the time to watch the whole thing:
