What We Owe the Future

CHAPTER 1

The Case for Longtermism

The Silent Billions

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.

Future people count, but we rarely count them. They cannot vote or lobby or run for public office, so politicians have scant incentive to think about them. They can’t bargain or trade with us, so they have little representation in the market. And they can’t make their views heard directly: they can’t tweet, or write articles in newspapers, or march in the streets. They are utterly disenfranchised.

Previous social movements, such as those for civil rights and women’s suffrage, have often sought to give greater recognition and influence to disempowered members of society. I see longtermism as an extension of these ideals. Though we cannot give genuine political power to future people, we can at least give consideration to them. By abandoning the tyranny of the present over the future, we can act as trustees—helping to create a flourishing world for generations to come. This is of the utmost importance. Let me explain why.

Future People Count

The idea that future people count is common sense. Future people, after all, are people. They will exist. They will have hopes and joys and pains and regrets, just like the rest of us. They just don’t exist yet.

To see how intuitive this is, suppose that, while hiking, I drop a glass bottle on the trail and it shatters. And suppose that if I don’t clean it up, later a child will cut herself badly on the shards.1 In deciding whether to clean it up, does it matter when the child will cut herself? Should I care whether it’s a week, or a decade, or a century from now? No. Harm is harm, whenever it occurs.

Or suppose that a plague is going to infect a town and kill thousands. You can stop it. Before acting, do you need to know when the outbreak will occur? Does that matter, just on its own? No. The pain and death at stake are worthy of concern regardless.

The same holds for good things. Think of something you love in your own life; maybe it’s music or sports. And now imagine someone else who loves something in their life just as much. Does the value of their joy disappear if they live in the future? Suppose you can give them tickets to see their favourite band or the football team they support. To decide whether to give them, do you need to know the delivery date?

Imagine what future people would think, looking back at us debating such questions. They would see some of us arguing that future people don’t matter. But they look down at their hands; they look around at their lives. What is different? What is less real? Which side of the debate will seem more clear-headed and obvious? Which more myopic and parochial?

Distance in time is like distance in space. People matter even if they live thousands of miles away. Likewise, they matter even if they live thousands of years hence. In both cases, it’s easy to mistake distance for unreality, to treat the limits of what we can see as the limits of the world. But just as the world does not stop at our doorstep or our country’s borders, neither does it stop with our generation, or the next.

These ideas are common sense. A popular proverb says, “A society grows great when old men plant trees under whose shade they will never sit.”2 When we dispose of radioactive waste, we don’t say, “Who cares if this poisons people centuries from now?” Similarly, few of us who care about climate change or pollution do so solely for the sake of people alive today. We build museums and parks and bridges that we hope will last for generations; we invest in schools and longterm scientific projects; we preserve paintings, traditions, languages; we protect beautiful places. In many cases, we don’t draw clear lines between our concerns for the present and the future—both are in play.

Concern for future generations is common sense across diverse intellectual traditions. The Gayanashagowa, the centuries-old oral constitution of the Iroquois Confederacy, has a particularly clear statement. It exhorts the Lords of the Confederacy to “have always in view not only the present but also the coming generations.”3 Oren Lyons, a faithkeeper for the Onondaga and Seneca nations of the Iroquois Confederacy, phrases this in terms of a “seventh-generation” principle, saying, “We… make every decision that we make relate to the welfare and well-being of the seventh generation to come.… We consider: will this be to the benefit of the seventh generation?”4

However, even if you grant that future people count, there’s still a question of how much weight to give their interests. Are there reasons to care more about people alive today?

Two reasons stand out to me. The first is partiality. We often have stronger special relationships with people in the present, like family, friends, and fellow citizens, than with people in the future. It’s common sense that you can and should give extra weight to your near and dear.

The second reason is reciprocity. Unless you live as a recluse in the wilderness, the actions of an enormous number of people—teachers, shopkeepers, engineers, and indeed all taxpayers—directly benefit you and have done so throughout your life. We typically think that if someone has benefited you, that gives you a reason to repay them. But future people don’t benefit you the way others in your generation do.5

Special relationships and reciprocity are important. But they do not change the upshot of my argument. I’m not claiming that the interests of present and future people should always and everywhere be given equal weight. I’m just claiming that future people matter significantly. Just as caring more about our children doesn’t mean ignoring the interests of strangers, caring more about our contemporaries doesn’t mean ignoring the interests of our descendants.

To illustrate, suppose that one day we discover Atlantis, a vast civilisation at the bottom of the sea. We realise that many of our activities affect Atlantis. When we dump waste into the oceans, we poison its citizens; when a ship sinks, they recycle it for scrap metal and other parts. We would have no special relationships with the Atlanteans, nor would we owe them repayment for benefits they had bestowed on us. But we should still give serious consideration to how our actions affect them.

The future is like Atlantis. It, too, is a vast, undiscovered country;6 and whether that country thrives or falters depends, in significant part, on what we do today.

The Future Is Big

It’s common sense that future people count. So, too, is the idea that, morally, the numbers matter. If you can save one person or ten from dying in a fire, then, all else being equal, you should save ten; if you can cure a hundred people or a thousand of a disease, you should cure a thousand. This matters, because the number of future people could be huge.

To see this, consider the long-run history of humanity. There have been members of the genus Homo on Earth for over 2.5 million years.7 Our species, Homo sapiens, evolved around three hundred thousand years ago. Agriculture started just twelve thousand years ago, the first cities formed only six thousand years ago, the industrial era began around 250 years ago, and all the changes that have happened since then—transitioning from horse-drawn carts to space travel, leeches to heart transplants, mechanical calculators to supercomputers—occurred over the course of just three human lifetimes.8

How long will our species last? Of course, we don’t know. But we can make informative estimates that take our uncertainty into account, including our uncertainty about whether we’ll cause our own demise.

To illustrate the potential scale of the future, suppose that we only last as long as the typical mammalian species—that is, around one million years.9 Also assume that our population continues at its current size. In that case, there would be eighty trillion people yet to come; future people would outnumber us ten thousand to one.

Of course, we must consider the whole range of ways the future could go. Our life span as a species could be much shorter than that of other mammals if we cause our own extinction. But it could also be much longer. Unlike other mammals, we have sophisticated tools that help us adapt to varied environments; abstract reasoning, which allows us to make complex, long-term plans in response to novel circumstances; and a shared culture that allows us to function in groups of millions. These help us avoid threats of extinction that other mammals can’t.10

This has an asymmetric impact on humanity’s life expectancy. The future of civilisation could be very short, ending within a few centuries. But it could also be extremely long. The earth will remain habitable for hundreds of millions of years. If we survive that long, with the same population per century as now, there will be a million future people for every person alive today. And if humanity ultimately takes to the stars, the timescales become literally astronomical. The sun will keep burning for five billion years; the last conventional star formations will occur in over a trillion years; and, due to a small but steady stream of collisions between brown dwarfs, a few stars will still shine a million trillion years from now.11

The real possibility that civilisation will last such a long time gives humanity an enormous life expectancy. A 10 percent chance of surviving five hundred million years until the earth is no longer habitable gives us a life expectancy of over fifty million years; a 1 percent chance of surviving until the last conventional star formations give us a life expectancy of over ten billion years.12

Ultimately, we shouldn’t care just about humanity’s life expectancy but also about how many people there will be. So we must ask: How many people in the future will be alive at any one time?

Future populations might be much smaller or much larger than they are today. But if the future population is smaller, it can be smaller by eight billion at most—the size of today’s population. In contrast, if the future population is bigger, it could be much bigger. The current global population is already over a thousand times larger than it was in the hunter-gatherer era. If global population density increased to that of the Netherlands—an agricultural net exporter—there would be seventy billion people alive at any one time.13 This might seem fantastical, but a global population of eight billion would have seemed fantastical to a prehistoric hunter-gatherer or an early agriculturalist.

Population size could get dramatically larger again if we one day take to the stars. Our sun produces billions of times as much sunlight as lands on Earth, there are tens of billions of other stars across our galaxy, and billions of galaxies are accessible to us.14 There might therefore be vastly more people in the distant future than there are today.

Just how many? Precise estimates are neither possible nor necessary. On any reasonable accounting, the number is immense.

To see this, look at the following diagram. Each figure represents ten billion people. So far, roughly one hundred billion people have ever lived. These past people are represented as ten figures. The present generation consists of almost eight billion people, which I’ll round up to ten billion and represent with a single figure:

Next, we’ll represent the future. Let’s just consider the scenario where we stay at current population levels and live on Earth for five hundred million years. These are all the future people:

Represented visually, we begin to see how many lives are at stake. But I cut the diagram short. The full version would fill twenty thousand pages—saturating this book a hundred times over. Each figure would represent ten billion lives, and each of those lives could be flourishing or wretched.

Earlier, I suggested that humanity today is like an imprudent teenager: most of our life is ahead of us, and decisions that impact the rest of that life are of colossal importance. But, really, this analogy understates my case. A teenager knows approximately how long she can expect to live. But we do not know humanity’s life expectancy. We are more like a teenager who, for all she knows, might accidentally cause her own death in the next few months but also might live for a thousand years. If you were in such a situation, would you think seriously about the long life that might be ahead of you, or would you ignore it?

The sheer size of the future can be dizzying. Typically, “longterm” thinking involves attention to years or decades at most. But even with a low estimate of humanity’s life expectancy, this is like a teenager believing that longterm thinking means considering tomorrow but not the day after.

Despite how overwhelming thoughts of our future can be, if we truly care about the interests of future generations—if we recognize that they are real people, capable of happiness and suffering just like us—then we have a duty to consider how we might impact the world they inhabit.

The Value of the Future

The future could be very big. It could also be very good—or very bad.