Does economics make you selfish?

Ray Fisman reports:

All students [at Yale Law School] are required to take courses in contracts and in torts, and they're randomly assigned to an instructor for each class. Some of these teachers have Ph.D.s in economics, some in philosophy and other humanities, and some have no strong disciplinary allegiances at all. Professors are encouraged to design their courses as they see fit. Instructors from economics may emphasize the role of contracts in making possible the efficiency gains of the marketplace, while philosophers may emphasize equal outcomes for contracting parties. So economists teach about efficiency and philosophers teach about equality.

To figure out whether this affected their young charges, we put 70 Yale Law students in a computer lab, and had them play a game that would reveal to us their views on fairness....It turns out that exposure to economics makes a big difference in how students split the pie, in terms of both efficiency and outright selfishness. Students assigned to classes taught by economists were more likely to give a lot when it was cheap to do so. But they were also much more likely to take the whole pie for themselves.