And obviously we have reasons to care about the welfare and interests of the people alive today.

But the long-term is claims that we also have reasons to care about people

who aren't yet born.

And that might be a much, much bigger number than 8 billion.

Yeah, that's exactly right. Because I think that humanity's life expectancy could be very large indeed. If you consider the lifespan of a typical mammal species that's about a million years, Homo sapiens has been around for about 300,000 years. That would mean there's 700,000 years still to go.

And we're actually not a typical mammal species, so we could go extinct much sooner than that, perhaps within the next few centuries even. Or we could live much longer,

the potentially hundreds of millions of years that Earth

remains habitable,

or the potentially hundreds of billions of years that we could survive if we one day

escaped Earth and took to the stars.

Now, somebody might say, well, of course we should be worried about the future, but future lives are not nearly as important as current lives. We should discount the moral value of future lives. We discount all the time interest rates for a mechanism for discounting. If somebody offers to pay me 100 pounds a year from now, well,

that's not worth as much to me as receiving 100 pounds today.

Somebody would have to offer to pay me more than 100 pounds in a year

if it's to be worth 100 pounds today.

So we discount all the time. Why not discount future lives?

Well, there's two reasons for discounting. One is discounting financial benefits. And you might do that if you think that money in the future is less valuable than money now. And that might be for the few reasons. One is because you can invest money now and so have more money later. And others, if you think future people are going to be richer, an additional kind of financial windfall will be worth less to them. And I think there's a good reasons to discount, at least in those situations where they apply. But there's another reason that you might have for discounting,

which is just

you might think intrinsically well-being is worth less the further it is in the future.

And I think that view is not correct. So if you imagine a choice between one of two outcomes,

you could alter. So you could prevent the death of a single person in 10,000 years time, or you could prevent the deaths of a million people in 11,000 years time. I think it's pretty clear. It's pretty intuitive that you should prevent the million deaths. And the fact that those people will live a thousand years later is

neither here nor there.

However, if you were to keep discounting well-being at the standard kind of economist's rate of 2% per year,

that would mean that actually you should save the one life in 10,000 years. And I just think that's absurd. At least past some point into the future, just harm is harm, benefits and harms, they count the same, no matter when in time they occur.