The Altruism Puzzle: The Obligation to Sacrifice One’s Life Harry Brighouse The obligation to sacrifice oneself in the scenario described by the puzzle is stringent. Because this seems so obvious to me, it is hard to discern what arguments will move the unconvinced. I offer an argument I find persuasive, and consider some objections. Let’s start with a variant of the altruism puzzle in which many people will have the intuition that killing someone else is required. Imagine I am in a different city from the one under threat. John, an innocent man beside me, has unknowingly undergone a procedure that makes him the trigger of the bomb. The bomb in the city under threat is set to detonate when John takes his 1,000th breath after 11 a.m. He is currently taking his 980th breath. I have a gun, and can kill him instanta- neously with it. John is not at all implicated in the plot. He is a good person, gives joy to others, and has a flourishing enjoyable life. The bombers subjected John to the procedure while he was asleep. It left no traces. He is innocent of the plot and has no reason to suspect anything. But I have an obligation to sacrifice John’s life. Killing him, by stipulation, is the only way of saving thousands of equally valuable lives. To deny the obligation just seems to me not take seriously the scale of the destruction the bomb will cause. Killing him will certainly be very bad. It is bad that he loses his life, and bad that I act in a way that contradicts my sense of who I really am (a pacific person who does not take the lives of others)—undermines my integrity. Maybe I will suffer severe emotional costs in the future as a result of my sense of responsibility for having taken John’s life, despite understanding it was my duty. But these quite real bads, and all others generated by the act, are massively outweighed by the good of saving the thousands of other people. So I am obliged to kill John. But what is the difference between killing him and sacrificing myself? Just that, in general, we are obliged to be more cautious about imposing costs on innocent others, especially serious costs like killing, than on our innocent selves. We must be more parsimonious with the lives of others than with our own. If I must kill John when that is the only way of preventing detonation, then I must sacrifice myself when that is the only effective way. Consider three objections. First, is it overdemanding for morality to require such self-sacrifice? It is, certainly, demanding—sacrificing oneself is a consider- able demand. But it is not something we cannot do: people do sacrifice themselves JOURNAL of SOCIAL PHILOSOPHY, Vol. 44 No. 2, Summer 2013, 115–117. © 2013 Wiley Periodicals, Inc.