Do we all have a categorical duty to tell the truth, even to a murderer? The fourth of Michael Sandel's famous lectures on the philosophy of justice looks at the German philosopher Immanuel Kant, whose stringent theory of morality allowed for no exceptions. Kant believed that telling a lie, even a white lie, was a violation of one's own dignity.

Sandel tests Kant's theory with his famous hypothetical scenario, The Killer at Your Door. If a friend were hiding inside your home and a person intent on killing them came to your door and asked you where they were, would it be wrong to tell a lie? If so, would it be moral to try to mislead the murderer without actually lying to them? This leads to a discussion of the morality of misleading truths.

Sandel wraps up the lecture with a video clip of one of the most famous recent examples of dodging the truth, President Clinton talking about his relationship with Monica Lewinsky. Show less