The American political philosopher Michael Sandel, whom I profiled for the NS in June this year, has been teaching Justice, an undergraduate course in moral and political philosophy, at Harvard for nearly 30 years now. It's wildly popular, having attracted more than 14,000 students over the years. Watching the video footage of his classes recently made available online by Harvard, as part of a collaboration with a local TV station in Boston, it is easy to see why Justice is always oversubscribed.

In a previous life, I taught philosophy at several English universities, and I know how hard it is to animate or enliven the same hoary old problems in ethics and political theory year in, year out. But Sandel manages to make the liberalism-communitarianism debate, for instance, seem like the most urgent thing in the world -- which, in a way, it is, of course. He is a thoroughly compelling and beguiling presence in the lecture theatre. Here, for example, is episode 11 on "The Claims of Community", in which Sandel deals with "Kant's reply to Aristotle":