Ah nice, thanks for explaining! I’m not following all the calculations still, but that’s on me, and I think they’re probably right.
But I don’t think your argument is actually that relevant to what we should do, even if it’s right. That’s because we don’t care about how good our actions are as a fraction/multiple of what our other options are. Instead, we just want to do whatever leads to the best expected outcomes.
Suppose there was a hypothetical world where there was a one in ten chance the total figure population was a billion, and 90% chance the population was two. And suppose we have two options: save one person, or save half the people.
In that case, the expected value of saving half the people would be 0.9*1 + 0.1*500,000,000 = about 50,000,001. That’s compared to the expected value of 1 of saving one person. Imo, this is a strong reason for picking the “save half the people option”.
But the expected fraction of people saved by the options is quite different. The “save half” option always results in half being saved. And the expected value of the “save one” option is also very close to half: 0.9*0.5 + 0.1*1/1,000,000,000. Even though the two interventions look very similar from this perspective, I think it’s basically irrelevant—expected value is the relevant thing.
What do you think? I might well have made a mistake, or misunderstood still.
Thanks, this back and forth is very helpful. I think I’ve got a clearer idea about what you’re saying.
I think I disagree that it’s reasonable to assume that there will be a fixed N = 10^35 future lives, regardless of whether it ends up Malthusian. If it ends up not Malthusian, I think I’d expect the number of people in the future to be far less than whatever the max imposed by resource constraints is, ie much less than 10^35.
So I think that changes the calculation of E[saving one life], without much changing E[preventing extinction], because you need to split out the cases where Malthusianism is true vs false.
E[saving one life] is 1 if Malthusianism is true, or something fraction of the future if Malthusianism is false, but if it’s false, then we should expect the future to be much smaller than 10^35. So the EV will be much less than 10^35.
E[preventing extinction] is 10^35 if Malthusianism is true, and much less if it’s false. But you don’t need that high a credence to get an EV around 10^35.
So I guess all that to say that I think your argument is right and also action relevant, except I think the future is much smaller in non-Malthusian worlds, so there’s a somewhat bigger gap than “just” 10^10. I’m not sure how much bigger.
What do you think about that?