What is What We Owe the Future about?

What We Owe the Future is philosopher William MacAskill's case for "longtermism" — the view that positively influencing the long-run trajectory of human civilization should be a primary moral priority. MacAskill's argument rests on scale: the number of future people who could exist if civilization continues for millions of years vastly outnumbers the present population, and if future people's lives matter morally, then even small changes to the probability of long-run flourishing represent enormous value. The book is both a philosophical argument and a practical guide to thinking about what that means.

MacAskill opens by establishing the scope of the future. If humanity survives even a modest fraction of the time the sun will continue to shine, the number of future lives dwarfs all current and past human lives combined. This is not science fiction speculation — it is simple arithmetic. The implication MacAskill draws is that premature human extinction is, by this calculus, among the worst things that could happen. Not because of what living people would lose, but because of all the people who would never exist. This is where the argument becomes controversial: it depends on a "totalist" view of population ethics that many philosophers reject, and MacAskill acknowledges the objections at length.

The book's second major concern is "value lock-in": the possibility that a future civilization might be permanently shaped by values dominant in the period that first gains decisive technological power. MacAskill is worried about both totalitarian lock-in (a global authoritarian regime that never relaxes its grip) and corporate lock-in (a small group of firms that entrench their values worldwide). He argues that maintaining diversity and balance of power is valuable not just instrumentally but as insurance against having the wrong values locked in.

The most concrete chapters address what individuals and institutions can do. MacAskill argues for taking existential risk from pandemics and AI seriously, for the importance of maintaining functioning institutions and democratic norms, and for the personal choice to work on neglected high-leverage problems. He applies the effective altruism framework throughout: focus where the cause is large, tractable, and neglected. The argument is that the long-run future is large, tractable enough to influence, and deeply neglected.

What We Owe the Future is a genuinely ambitious argument that takes its conclusions seriously. MacAskill does not hedge the implications: if longtermism is correct, it should reshape which careers people choose, where charitable dollars go, and how governments set priorities. Readers unconvinced by population ethics will resist the foundations, but the subsidiary arguments — about preserving institutional diversity, taking AI risk seriously, and the limits of moral overconfidence — stand somewhat independently.