# Population ethics and the value of variety

Problems in population ethics (are 2 lives at 2 utility better than 1 life at 3 utility?) are similar to problems about lifespan of a single person (is it better to live 2 years with 2 utility per year than 1 year with 3 utility per year?)

On the surface, this analogy seems to favor total utilitarianism. 2 years at 1 happiness seems obviously better than 1 year at 1.01 happiness, to the point that average utilitarianism becomes just silly. And 4 years at 0.9 seems better still. In the normal range, without getting into astronomical numbers, it does seem multiplying utility/year by years is a good first approximation of what our intuition does.

But does this mean total utilitarianism is our best approximation to population ethics as well? Not so fast. Let's imagine taking an amnesia pill after each year, or after each month. To me at least, it feels like the intuition in favor of summing gets weaker, and the intuition in favor of averaging gets slightly stronger.

Why would amnesia make life less valuable? Well, one scary thing about amnesia is that if we don't remember past experience, we're just going to repeat it. And repeating a past experience feels less valuable than experiencing something new. Let's test that intuition! Imagine 10 equally happy people, all exactly alike. Now imagine 10 equally happy people, all different. The latter feels more valuable to me, and I think to many others as well.

So if we value variety, and that affects our intuition on whether utilities should be summed or averaged, does that carry over to other population ethics problems? I think so, yeah. When someone mentions "100 identical copies of our universe running in parallel", we find it hard to care about it much more than about just 1 copy. But if they'd said all these universes were as good as ours but interestingly different, ooh! That would sound much more appealing. Same if someone mentions "adding many lives barely worth living": if they also said that all these above-zero lives were also interestingly different, it'd no longer sound like such a bad bargain. And so on.

An even more interesting angle is: if we value variety, variety of what? It's tempting to answer "variety of experience", because we're used to thinking of happiness as something you experience. But that's not quite the full answer. Eating the same flavor of ice cream twice, with amnesia in-between, is plausibly twice as valuable as eating it once - it doesn't matter if you forgot what you ate yesterday, you still want to eat today. Whereas watching a great movie twice with amnesia in-between feels like a more iffy proposition - the amnesia starts to feel like a loss of value. But the real flip happens when we stop thinking about consumption (of things, experiences, etc) and think about creation. How would you like to be a musician who wrote a song, then got amnesia and wrote the same song again? This is less like summing of utilities and more like a horrorshow. So with creative activities we value variety very much indeed.

And this I think gets pretty close to the center of disagreement between total and average utilitarianism. Maybe they don't actually disagree; they just apply to different things we value. There are repeatable pleasures like eating ice cream, which it makes sense to add up, but they're only a part of what we value. And then there are non-repeatable good things, like seeing a movie for the first time, or creating something new. We value these things a lot, but for their utility to add up, they must be varied, not merely repeated.