Future people count. There could be a lot of them. We can make their lives go better.

This is the case for longtermism in a nutshell. The premises are simple, and I don’t think they’re particularly controversial. Yet taking them seriously amounts to a moral revolution—one with far-reaching implications for how activists, researchers, policy makers, and indeed all of us should think and act.

Values changes are significant because they have major impacts on the lives of people and other beings. But from a longtermist perspective, they are particularly significant compared to other sorts of changes we might make because their effects are unusually predictable.

If you promote a particular means of achieving your goals, like a particular policy, you run the risk that the policy might not be very good at achieving your goal in the future, especially if the world in the future is very different from today, with a very different political, cultural, and technological environment. You might also lose out on the knowledge that we will gain in the future, which might change whether we even think that this policy is a good idea. In contrast, if you can ensure that people in the future adopt a particular goal, then you can trust them to pursue whatever strategies make the most sense, in whatever environment they are in and with whatever additional information they have. You can therefore be fairly confident that you have made the achievement of that goal more likely, even if you have no idea at all what the world will be like when those future people act.

For these reasons changing values has particularly great significance from a longterm perspective. Looking to the past, we see that such changes have had an enormous impact on the lives of billions of people. Looking to the future, if we can improve the values that guide the behaviour of generations to come, we can be pretty confident that they will take better actions, even if they’re living in a world very different from our own, the nature of which we cannot predict.

But if we are guilty of gross moral errors ourselves, then locking in our present values would also be a disaster.

Instead, we should try to ensure that we have made as much moral progress as possible before any point of lock-in. Political philosophers often argue over what an ideal state would look like. I think we should accept that we don’t know what the ideal state would be; the primary question is how we can build a society such that, over time, our moral views improve, people act more often in accordance with them, and the world evolves to become a better, more just place.

Positive moral change is not inevitable. It’s the result of long, hard work by generations of thinkers and activists. And if there’s any change that’s not inevitable, it’s concern for future people—people who, by virtue of their location in time, are utterly disenfranchised in the world today.

If we are careful and far-sighted, we have the power to help build a better future for our great-grandchildren, and their great-grandchildren— down through hundreds of generations. But we cannot take such a future for granted. There’s no inevitable arc of progress. No deus ex machina will prevent civilisation from stumbling into dystopia or oblivion. It’s on us. And we are not destined to succeed.