IMAGINE a child, running barefoot through a forest, and a broken glass bottle buried just beneath the soil. What鈥檚 worse: that a present-day child steps on the shards, or that a child in 100 years from now does?
This question, posed by philosopher Derek Parfit in the 1980s, was intended to clarify our moral obligations towards unborn generations. Knowingly risking harm to a future person, he argued, is just as bad whether it is today or in a century.
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Parfit鈥檚 ideas inspired a branch of moral philosophy called longtermism. It rests on three premises: future people matter, there could be a lot of them and we have the power to make their lives better or worse. Ensuring the future goes well should therefore be a key moral priority of our time.
All of which seems reasonable, at first glance: it apparently promotes the universal values of stewardship, the duty to posterity and being a 鈥済ood ancestor鈥�. But longtermism has proven controversial, with some critics arguing that it is a 鈥渄angerous ideology鈥� that permits or even encourages the suffering of people alive today.
Is that fair? To make up your own mind, the first thing you need to know is that longtermism comes in different flavours. Many of the most strident criticisms focus on the implications of , a variant introduced in a 2021 paper by the University of Oxford鈥檚 Hilary Greaves and William MacAskill, which says that it should be the top moral priority of our time.
This would have striking consequences for how money is spent in the real world. Indeed, it is already having an influence. The leading advocates of longtermism work in the world of billion-dollar philanthropy and 鈥渆ffective altruism鈥�, where huge sums are allocated to causes based on reasoning about the world鈥檚 most pressing problems and the most efficient ways to tackle them. Longtermism has tangibly shaped how foundations and billionaire donors spend their money on research, activism and political races.
The problems with longtermism
Right now, many longtermists are more worried about the existential dangers posed by artificial intelligence than, say, social justice or homelessness. And it is this willingness to rank distant, hypothetical risks above the needs of people alive today that makes them unpopular.
Even those who study existential risk, such as Carla Zoe Cremer at the University of Oxford and Luke Kemp at the University of Cambridge, worry that longtermist efforts are and serving the interests of elite, unelected technocrats.
But there鈥檚 more. For many, longtermism is inherently unpalatable and dangerous because the number of future people could be enormous, and a moral framework that accounts for all their needs inevitably dwarfs those of people alive today.
The fear is that longtermism could evolve into a form of mathematical blackmail, where reducing existential risk by a small percentage in 1000 years, say, seems a better use of resources and leads to the neglect of immediate problems like climate change. It might even justify harmful acts in the name of the greater, future good.
With all that said, it is important to note that longtermism is still evolving and its strongest form isn鈥檛 the only version of it. Among others, there is weak longtermism, which simply says we should seek ways to ensure the future goes well: this would be one moral priority, but not necessarily top of the list. Which version, if any, will find greater influence remains to be seen.
Parfit was aware that the questions he posed lacked simple answers. It took another generation to fashion his ideas into longtermism. Now, amid the controversy, perhaps it will require a new generation to figure out where longtermism goes next.
