Kant's Categorical Imperative

A familiar Columbia legend: Sidney Morgenbessser, professor of philosophy, now emeritus, was smoking in the subway. A transit cop came up to Professor Morgenbesser and demanded that he put out his pipe. "What if everyone smoked?" the cop said, reprovingly. "Who are you— Kant?" the irritated professor asked, whereupon the policeman, misunderstanding "Kant" as something else, hauled Sidney Morgenbesser off to the precinct house.

The transit cop, willingly or not, was applying Immanuel Kant's injunction to make up one's mind about the moral appropriateness of any particular act by using the "categorical imperative"—the demand that one act as if one were legislating for all of mankind. By that standard, if everyone smoked, the subway would be a foul, stinking mess.