Peter Singer on anti-aging research

In the past, Peter Singer has expressed opposition to anti-aging technology (perhaps a pill that slows down aging by half) on utilitarian grounds. He has argued that a universe where half as many people are born over time, but with individual people living for twice as long, would (or could) be less happy overall. This is because very long-lived people might be less happy in the second half of their lives than in the first half of their lives, and than “ordinary” people when their happiness is averaged over the course of an “ordinary” life span. This is partly because life might seem to lose a certain freshness with age – Singer makes that assumption, though it may be wrong.

Note also Singer’s assumption that resource constraints would require that the same number of person-years be lived in a given block of space-time. This is achievable, at least subject to some transitional effects, by people who live twice as long still only having the same number of children. The idea is to space out the birth of children so that they are born only half as often. It works out that at any given time the total population is the same. It took me a lot of work to be sure that this really is how the arithmetic comes out, but it does.

I replied at some length to Singer a few years ago now, in an article published in The Journal of Medical Ethics. If you have access, you might like to check out the whole article. I put arguments as to why a space-time block with half as many people who live twice as long (say, 150 or 160 years) is more desirable than one with “ordinary” people who live to an “ordinary” old age (say, 75 or 80 years). The arguments are tricky, and I’m by no means sure there is a “right” answer; but I think my analysis is at least as plausible as Singer’s, even if we make the assumptions that he does. (Whether those assumptions are plausible is another story.)

Singer has recently published this piece in which he seems much more sympathetic to the idea of a world with longer-lived people, and toward anti-aging research such as advocated by Aubrey de Grey. I don’t know whether he has actually changed his mind, or whether he is merely trying to foster debate, but it’s an interesting development. If he has changed his mind, I’m not claiming any credit – I’m not aware whether he’s even read my JME article.

H/T Jean Kazez.