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.

This suggests that, as longtermists, when trying to improve society’s values, we should focus on promoting more abstract or general moral principles or, when promoting particular moral actions, tie them into a more general worldview. This helps ensure that these moral changes stay relevant and robustly positive into the future.

When we look at history, we see that the predominant culture in a society tends to entrench itself, eliminate the competition, and take steps to replicate itself over time. Indeed, many moral views regard their own lock-in as desirable.

This last point—that we need to structure global society so that cultural evolution guides the world towards better values and better societal structures—highlights an issue facing the design of a morally exploratory world that I’ll call the lock-in paradox. We need to lock in some institutions and ideas in order to prevent a more thoroughgoing lock-in of values. One challenge is that these institutions and ideas will be morally controversial; for example, from many fundamentalist religious perspectives, the idea that we would encourage or even allow a diversity of worldviews might be regarded as abominable. Similarly, the idea that the path to the correct moral view is via reflection and good-faith debate, rather than studying the scripture of a holy book, is not one that everyone would accept.

The lock-in paradox thus resembles the familiar paradox of tolerance— the necessity for liberal societies to defend themselves against intolerant views that would undermine their freedom, even if doing so requires curtailing the very tolerance they want to preserve.

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.