Would You Kill the Fat Man?

Consider the following scenario. Terrorists have hijacked three passenger aeroplanes, two of which have just been flown into skyscrapers in the middle of a busy city. On its first run, the third plane missed its target, but it is now lining up for another attempt. In the meantime, you – the head of the Air Force – have been able to scramble a fighter jet, which can shoot down the plane before it reaches the skyscraper. (There is not enough time to evacuate the building.) Several hundred innocent people will die as a result of this action, and thousands will be saved by it. It’s your call. What do you do?

If you’ve ever engaged in such speculations, then you are a student, whether you know it or not, of the philosophical sub-discipline of ‘trolleyology’ – a series of ethical thought experiments that draws on philosophers from Thomas Aquinas to Immanuel Kant to Jeremy Bentham and that, despite its rather jokey label, has implications for how we fight wars, distribute justice and respond to emergencies. Indeed, according to David Edmonds in his new book Would You Kill the Fat Man?, this controversial branch of ethics throws a crucial sidelight on our moral intuitions; for him, the so-called Trolley Problem goes to the heart of what it means to be human.

Formulated by the philosopher Philippa Foot, the original version of the Trolley Problem appeared in 1967. Edmonds calls this version ‘Spur’, for reasons that his paraphrase make obvious:

A man is standing by the side of the track when he sees a runaway train hurtling towards him: clearly the brakes have failed. Ahead are five people, tied to the track. If the man does nothing, the five will be run over and killed. Luckily he is next to a signal switch: turning this switch will send the out-of-control train down a side track, a spur, just ahead of him. Alas, there is a snag: on the spur he spots one person tied to the track: changing direction will inevitably result in this person being killed. What should he do?

This is the problem in its straightforward form and it tends to elicit a straightforward response: most say the man should turn the switch. (In fact, when pressed, the majority responds that it is morally incumbent on him to do so.) But in 1976 Judith Jarvis Thomson, a philosopher at the Massachusetts Institute of Technology, put forward another version of the problem. In this version, the man is standing on a footbridge when he sees the train running out of control. Standing next to him, leaning over the bridge, is a man of such bulk that, were he to fall (or be pushed) on to the tracks, he would stop the train. The fat man would die, but the five would be saved. Hence the question, ‘Would you kill the fat man?’

The fact that most people answer ‘no’ to this question presents an intriguing philosophical problem, which Edmonds sets out with clarity and verve. For him, and for many philosophers besides, the difference between the two responses hinges on the question of intention. In Spur, the intention is not to kill the (single) person tied to the track; that person’s death is merely a consequence of diverting an already existing threat. By contrast, Fat Man entails a decision to actively kill a human being. To put it another way: most seem to take the Kantian view that human beings are ends in themselves (and should not be treated as means to an end) and reject the hardline utilitarian view that the happiness of the majority should always prevail.

Two of Edmonds’ previous books – Wittgenstein’s Poker and Rousseau’s Dog – have had titles of the ‘bathetic possessive’ variety, where the intention is to signal a serious subject treated in a light-hearted way. This approach has many merits, but it also brings with it certain problems, some of which are on display in Would You Kill the Fat Man? The humour is rather forced at times, and it’s not always clear why biographical material on the key philosophers is being included. My suspicion is that Edmonds is trying (too hard) to lighten the intellectual load. (There are countless versions of the Trolley Problem, and Edmonds acquaints us with many of them.) Worried about the bitterness of his intellectual pill, he’s resolved to coat it with saccharin.

In fact the pill isn’t bitter at all. Trolleyology may, as one philosopher put it, make the Talmud look like Cliffs Notes, but it’s a fascinating and important field. The light it throws on the moral intuitions of human beings is its own reward, and this book will makes its readers think, even if it doesn’t always make them laugh.

David Edmonds, Would You Kill the Fat Man? The Trolley Problem and What Your Answer Tells Us about Right and Wrong
PUP; $34.95; 212pp


First published in The Australian.