This is a rare treat—a serious, thought-provoking book on ethics that is also witty, funny, and entertaining. Not to be missed.
In Would You Kill the Fat Man?, philosopher, author, and broadcaster David Edmonds has taken the well-known trolley car problem and breathed new life into it, examining it from different perspectives and using it to shed light on the ethical theories of Immanuel Kant, Jeremy Bentham, John Rawls, Aristotle, and others. If you think philosophy has to be ponderous and difficult, you haven’t read this book.

The trolley problem, first introduced in 1967 by the British philosopher Philippa Foot, begins with the following dilemma: Imagine a trolley running out of control and headed toward a track on which five men have been tied. They all face certain death unless…

You happen to be standing at a switch that can turn the train onto a spur. Alas, that, too, will mean death, but only for a single man who’s tied to the tracks. Do you pull the switch, ending one life to save five? Most people say they would.

Now imagine a similar scenario but this time you’re standing on an overpass looking down as the trolley approaches. There’s no switch, but there is a very fat man standing alongside. You realize that if you push him over, he’ll fall on the track and his weight is enough to block the trolley, saving the five men tied down. Do you push? Most people say no.

Why the difference when in both cases five lives will be saved at the cost of one?

Several reasons, Edmonds suggests. In the first instance, you don’t intend to kill the single man, that’s just the consequence of saving the other five. It’s even possible the single man will somehow manage to free himself in time to escape. In the second, you do intend to kill the fat man. He must die for the plan to work. Plus there’s the actual act of pushing (murdering) the fat man. So in the end, for most of us, emotion trumps reason.

But for Edmonds that’s just the beginning. He offers all sorts of variations and permutations and examines how the problem changes with each. For example, does it matter if the single person on the spur is a child? Or your mortal enemy? Or if the five men on the main track are all over eighty? What if the setting is changed to a hospital and you’re a surgeon who can kill one innocent man and harvest his organs, thereby saving five other people? What if the man is on life support with little hope of recovery and time is short for the other five?

The book becomes even more interesting as Edmonds brings in the major ethical theories. Bentham, who believed in the greatest good for the greatest number, would have no problem killing the fat man, but Kant, who believed if murder is wrong in one instance, it’s wrong in all instances, would come down on the other side.

What’s intoxicating about this book is that every time you think you know what you think, Edmonds tosses out a new element—adding for example, the results of a study in which participants were shown either an hour of television comedy or a serious drama before being given the trolley problem. Those who watched comedy were far more willing to push the fat man. (They’re also far more willing to do so when those tied to the tracks are all animals instead of people.) What are we to make of that?

There’s lots more to enjoy and learn from this book, a real gem and one of my new favorites. You can also get a taste of the book by listening to or reading the transcript of an interview with Edmonds on Philosophy Bytes.

Would You Kill the Fat Man? The Trolley Problem and What Your Answer Tells Us about Right and Wrong. By David Edmonds, Princeton University Press, 2013, 240 pp.