Regarding the ‘second mistake’, I don’t see how it is very different from the first one. If there remains high average per-period risk, then the expected benefits of avoiding nearterm risk is indeed greatly lowered — from ‘overwhelming’ to just ‘large’. In effect, it starts to approach the level of risk to currently existing people (which is sometimes argued to be so large already that we don’t need to talk about future generations).
But it doesn’t seem unreasonable to me for Millet and Snyder-Beattie to model things with an expected lifespan for humanity equal to that of a typical species. It is true that if risk stays high, then we won’t get that, but risk staying high would be a more contentious assumption. And uncertainty about the final rate, tends to increase the expectation. e.g. If there was even a 1 in 400 chance that we last as long as the Nautilus, then that alone would make M & SB’s assumption an underestimate. Again, I can’t see any ‘mistake’ here.
I was actually much more intrigued by your comment about a systematic overestimate due to an implicit assumption of independence between the variables they estimate. I’d have loved to see that developed instead.
There is also room for an interesting critique of EV of risk reduction as the best measure. Your arguments generally put pressure on the idea that the estimate of M & SB (or other people’s duration estimates) are typical of the probability distribution. That is, they might be OK as estimates of the expectations (means), but they get much of that EV from the extreme tail of the distribution. And we might have Pascallian concerns about cases like that, where there is a decent case that we shouldn’t compare prospects like this by their expectations.
‘But risk staying high would be a more contentious assumption.’ Why? I take it this is really the heart of the disagreement, so it would be good to hear what makes you think this.
Regarding the ‘second mistake’, I don’t see how it is very different from the first one. If there remains high average per-period risk, then the expected benefits of avoiding nearterm risk is indeed greatly lowered — from ‘overwhelming’ to just ‘large’. In effect, it starts to approach the level of risk to currently existing people (which is sometimes argued to be so large already that we don’t need to talk about future generations).
But it doesn’t seem unreasonable to me for Millet and Snyder-Beattie to model things with an expected lifespan for humanity equal to that of a typical species. It is true that if risk stays high, then we won’t get that, but risk staying high would be a more contentious assumption. And uncertainty about the final rate, tends to increase the expectation. e.g. If there was even a 1 in 400 chance that we last as long as the Nautilus, then that alone would make M & SB’s assumption an underestimate. Again, I can’t see any ‘mistake’ here.
I was actually much more intrigued by your comment about a systematic overestimate due to an implicit assumption of independence between the variables they estimate. I’d have loved to see that developed instead.
There is also room for an interesting critique of EV of risk reduction as the best measure. Your arguments generally put pressure on the idea that the estimate of M & SB (or other people’s duration estimates) are typical of the probability distribution. That is, they might be OK as estimates of the expectations (means), but they get much of that EV from the extreme tail of the distribution. And we might have Pascallian concerns about cases like that, where there is a decent case that we shouldn’t compare prospects like this by their expectations.
‘But risk staying high would be a more contentious assumption.’ Why? I take it this is really the heart of the disagreement, so it would be good to hear what makes you think this.