If you popped into the Sanders Theatre at Harvard University on a particular day, you might think you were at the recording of some daytime television chat show. A slightly-built man in a smart suit paces confidently around the stage, hands behind his back, playfully throwing out questions to the packed audience about sex, gay relationships, money and torture.

Each time someone stands up to answer, he carefully repeats their words out loud as if to say: “So what do you all think of that, then?” before releasing a mischievous smile and motioning for the roving mic to be passed along the row to someone with their hand up.

There might be cameras, lights and technical staff in the theatre, but this is as far from a chat show that you could get. The figure on the stage is no Jerry Springer clone, but instead a teacher of political philosophy: Michael Sandel. To give him his full title, he’s the Anne T and Robert M Bass Professor of Government at Harvard.

He is also the man who made philosophy accessible, even cool. His appeal to the 1,000 students at Harvard who sign up for his course in justice each year is his easy conversational style and use of everyday examples from life to try and tease out answers to tricky ethical questions. So popular is he that the justice course has spawned groups all over the world, using videos and podcasts on the justice web site (www.justiceharvard.org) to trigger discussions.

Many in Britain probably heard Sandel for the first time earlier this year when he gave the BBC Reith Lectures in which he explored the morality of politics, the markets and genetics and argued for a renewal of what he called “civic virtue” based on the idea of the common good. Surprisingly in such a high-profile broadcast, he presented a powerful case for religion to be brought back into the centre of the big moral debates.