Would You Kill The Fat Man? is your latest book. Explain the meaning of the catchy title.
Scenario 1. A train is out of control. Its brakes have failed. Five men are tied to a track in front of the train. All five are facing imminent death. You are standing on the side of the track. You can turn a switch, diverting the train down a spur. Unfortunately, one man is tied to this spur track and if you divert the train this man will be killed. What should you do?
Scenario 2. A train is out of control. Once again five men, tied to the track ahead, are in mortal danger. You are standing on a footbridge next to a fat man. The only way you can save the five is by pushing the fat man over the bridge. He is so large that his bulk would stop the train, though he would die. What should you do?
Most people react very differently to the two scenarios. But why? This is the puzzle at the heart of the book. After all, in both cases it's a choice between one life or five
So, we really need to know, would you ever kill the fat man to save five others?
No. I think it would be quite wrong to kill the fat man (for reasons spelled out in the book!).
Are there any real-life examples of this ethical dilemma?
Well, not exactly like the Fat Man case, but the point of these scenarios is indeed to capture relevant moral distinctions in the real world. There's one interesting example I discuss from World War II. Churchill had to make a decision about whether to trick the Nazis about where their V1 missiles were landing. If the deception operation succeeded, the Nazis would fire their missiles into less populous parts of town - killing fewer (and different) people. One senior cabinet member argued strongly against the deception - insisting that it wasn't up to British politicians to play God.
Has philosophy helped or hindered your career as a programme maker?
Well, I've used the BBC on many occasions to indulge my hobby. One of my first documentaries was on the Problem of Evil - whether the existence of an all-powerful, all-good God was compatible with the existence of evil in the world. (It was a terrible programme.) I produce The Philosopher's Arms on Radio 4 (presented by Matthew Sweet). And this book had an earlier life as a series on the BBC World Service.
How did you end up falling in love with philosophy?
I initially studied it at university as part of my undergraduate degree, Politics, Philosophy and Economics (PPE). I found the other P too mundane, and the E too mathematical and hence too divorced from its purported subject matter. Philosophy struck me as satisfyingly difficult and fundamentally important.
Which philosopher has influenced you the most and why?
Wittgenstein is my great intellectual hero, the second most brilliant man of the 20th century after that other 'stein, Einstein. I can't claim, however, that reading him has changed my life in either large or small ways. He hasn't affected the type of bread I buy, or the political party I support. If you read Marx or Mill your values might shift. Wittgenstein doesn't have that kind of impact . . .
Wittgenstein's Poker is the best-selling book you co-authored with a fellow BBC colleague, John Eidinow. Sell us the book in 100 words or fewer.
It's a story about 10 minutes in 1946. Three brilliant men are in the same room together for the first and only time: Wittgenstein, Popper, Russell. They're attending a philosophy society. Wittgenstein gets very cross during Popper's talk, and waves a fireside poker at Popper whilst demanding an example of a moral principle. Popper says, 'Thou should not threaten visiting lecturers with pokers'. Wittgenstein storms out in a huff. This is Popper's account. But did Popper, as alleged by some, lie? We track down the witnesses! Those 10 minutes capture a dispute at the heart of 20th-century philosophy.