Some random thoughts on CEV:

1. To get the obvious disclaimer out of the way: I don't actually think any of this matters much for present-day alignment questions. I think we should as much as possible try to defer questions like this to future humans and AIs. And in fact, ideally, we should mostly be deferring to future AIs, not future people—if we get to the point where we're considering questions like this, that means we've reached superintelligence, and we'll either trust the AIs to be better than us at thinking about these sorts of questions, or we'll be screwed regardless of what we do.^[1]
2. Regardless, imo the biggest question that standard CEV leaves unanswered is what your starting population looks like that you extrapolate from. The obvious answer is "all the currently living humans," but I find that to be a very unsatisfying answer. One of the principles that Eliezer talks about in discussing CEV is that you want a procedure such that it doesn't matter who implements it—see Eliezer's discussion under "Avoid creating a motive for modern-day humans to fight over the initial dynamic." I think this is a great principle, but imo it doesn't go far enough. In particular:
   1. The set of all currently alive humans is hackable in various ways—e.g. trying to extend the lives of people whose values you like and not people whose values you dislike—and you don't want to incentivize any of that sort of hacking either.
   2. What about humans who recently died? Or were about to be born? What about humans in nearby Everett branches? There's a bunch of random chance here that imo shouldn't be morally relevant.
   3. More generally, I worry a lot about tyrannies of the present where we enact policies that are radically unjust to future people or even counterfactual possible future people.
3. So what do you do instead? I think my current favorite solution is to do a bit of bootstrapping: first do some CEV on whatever present people you have to work with just to determine a reference class of what mathematical objects should or should not count as humans, then run CEV on top of that whole reference class to figure out what actual values to optimize for.
   1. It is worth pointing out that this could just be what normal CEV does anyway if all the humans decide to think along these lines, but I think there is real benefit to locking in a procedure that starts with a reference class determination first, since it helps remove a lot of otherwise perverse incentives.