"We're going to engage in an experiment ....an experiment in public philosophy. We sometimes think that philosophy is remote, abstract and distant from the world we actually inhabit. I think otherwise". So says the eminent Harvard political philosopher Michael Sandel as he challenges an audience to examine the big ideas, the big philosophical questions that lie behind our views.

In a series of public events, recorded at the London School of Economics, he brings his trademark style to a discussion on a current issue. This week, he delves into the thorny issue of access to universities. "Should students from poor backgrounds be given priority in admissions?" he asks. He demands a show of hands. The brave ones volunteer to explain the thinking behind their views.

The audience is swept along. "Who decides if you're from a poor background...what does that mean to come from a poor background? The way our system works right now is fair because we're just numbers" says Georgia, arguing that academic results are all that matter.

Fazal's view, reflecting his experience of American universities, is very different. "On one piece of paper you're writing down your experiences, your grades. On the other you're writing down your financial background...how much money you can potentially pay".

Throughout, Michael Sandel acts as referee, thinker and devil's advocate.

His lectures to Harvard undergraduates have been described as "spellbinding...an exhilarating journey". They are popular, provocative and interactive. Now he brings that approach to Radio 4.

Producer: Adele Armstrong.