No one likes cleaning bathrooms, but most people like their bathrooms to be clean. When several people share a bathroom, a free rider game may manifest in which some attempt to free ride off the efforts of others.
He then goes on to describe how this type of game plays into the situation with Iraq and other foreign policy issues. It's an interesting article, and easy to understand. He concludes by writing:
After victory in Iraq, many will suggest we have a choice between acting morally or vengefully towards reluctant allies like France and Germany. I believe, however, that the vengeful path is also the moral one. If we don't reward our allies and punish our detractors, free rider problems will doom U.S. troops to act alone in future conflicts.
Spotted via Instapundit.