Are you a bull or a bear? A Tortoise or a hare? Your answer is not as important as how you arrived at it. The investment world's biggest divide these days is between two competing interpretations of reality: the efficient market theory and behavioral finance. The University of Chicago, where I am a trustee, is home to two of the most distinguished champions of these beliefs: Eugene Fama for the efficient market approach and Richard Thaler for the behavioral one. (Forbes)