Prisoner's Dilemma
Prisoner's Dilemma = famous thought experiment in Game Theory, about selfishness vs. altruism in the context of human cooperation.
More Information
See for a good review of the Prisoner’s Dilemma, this entry of the Wikipedia, at http://en.wikipedia.org/wiki/Prisoner's_dilemma
The following text is a good defense of the use of game theory in scientific research, at http://www.geocities.com/hmelberg/elster/AR82MFGT.HTM