Here’s the scenario. Walking across a bridge over a railroad one day, you notice that five people are tied to the tracks below. Worse, you also spot a speeding train approaching, with no sign of slowing down—it’s sure to plow through the five people, killing them. Suddenly you see the only possible way to save them: an exceptionally large man—large enough to derail an oncoming train, it just so happens—is leaning on the bridge’s railing above the tracks, resting. Now’s your chance: do you push the man over the railing, killing him, but saving the five people tied to the tracks? Or do you refrain from pushing him, thereby sparing his life but effectively allowing the five below to die?

Confident in your answer? Now consider this: What if the five people on the tracks are children, and the large man is a known terrorist? Would that change your decision? Why or why not? Our reasoning in these matters, says David Edmonds, has preoccupied moral philosophers for centuries, and the scenarios above are not as farfetched as they seem. 

In Would You Kill the Fat Man?, Edmonds invites us on a delightfully torturous journey through similar scenarios offered by various thinkers, who (oh, those philosophers!) tweak the details into ever more convoluted and complex moral dilemmas . What if your decision involves not bridges and railroads, but hospitals and patients, or bombs and cities?  What if it’s not you who carries out your decision at all, but someone else following your orders? Edmonds claims that each subtle shift in circumstances causes us, in turn, to shift our moral reasoning—but that, although our moral compasses recalibrate inexplicably easily, they’re surprisingly consistent across cultures and social classes.

If reading moral philosophy sounds as inviting as a root canal, don’t worry. Would You Kill the Fat Man? manages to dissect the ideas it discusses—and their implications for personal, social, and political values—with a playful and engaging tone. Like a one-player game of Would You Rather…?, this book allows us to enjoy, without having to share our answers, what we normally bristle at: making difficult, even agonizing choices with no comfortable results.