Thank you very much - I'm part way through Christian Tarsney's paper and definitely am finding it interesting. I'll also have a go at Hilary Greaves piece. Listening to her on 80,000 hours' podcast was one thing that contributed to asking this question. She seems (at least there) to accept EV as the obviously right decision criterion, but a podcast probably necessitates simplifying her views!
Thanks very much. I am going to spend some time thinking about the von-Neumann-Mortgenstern theorem. Despite my huge in-built bias towards believing things labelled "von-Neumann", at an initial scan I found only one of the axioms (transitivity) felt obviously "true" to me about things like "how good is the whole world?". They all seem true if actually playing games of chance for money of course, which seems to often be the model. But I intend to think about that harder.
On GiveWell, I think they're doing an excellent job of trying to answer these questions. I guess I tend to get a bit stuck at the value-judgement level (e.g. how to decide what fraction of a human life a chicken life is worth). But it doesn't matter much in practice because I can then fall back on a gut-level view and yet still choose a charity from their menu and be confident it'll be pretty damn good.
Hi Harrison. I think I agree strongly with (2) and (3) here. I'd argue Infinite expected values that depend on (very) large numbers of trials / bankrolls etc. can and should be ignored. With the Petersburg Paradox as state in the link you included, making any vaguely reasonable assumption about the wealth of the casino, or lifetime of the player, the expected value falls to something much less appealing! This is kind of related to my "saving lives" example in my question - if you only get to play once, the expected value becomes basically irrelevant because the good outcome just actually doesn't happen. It only starts to be worthwhile when you get to play many times. And hey, maybe you do. If there are 10,000 EAs all doing totally (probabilistically) independent things that each have a 1 in a million chance of some huge payoff, we start to get into realms worth thinking about.
Hi Larks. Thanks for raising this way of re-framing the point. I think I still disagree, but it's helpful to see this way of looking at it which I really hadn't thought of. I still disagree because I am assuming I only get one chance at doing the action and personally I don't value a 1 in a million chance of being saved higher than zero. I think if I know I'm not going to be faced with the same choice many times, it is better to save 10 people, than to let everyone die and then go around telling people I chose the higher expected value!
Thank you - this is all very interesting. I won't try to reply to all of it, but just thought I would respond to agree on your last point. I think x-risk is worth caring about precisely because the probability seems to be in the "actually might happen" range. (I don't believe at all that anyone knows it's 1/6 vs. 1/10 or 1/2, but Toby Ord doesn't claim to either does he?) It's when you get to the "1 in a million but with a billion payoff" range I start to get skeptical, because then the thing in question actually just won't happen, barring many plays of the game.
Dear All - just a note to say thank you for all the fantastic answers which I will dedicate some time to exploring soon. I posted this and then was offline for a day and am delighted at finding five really thoughtful answers on my return. Thank you all for taking the time to explain these points to me. Seems like this is a pretty awesome forum.