Yes: not capturing complexity of value.

'Your theory isn't complex enough' isn't a reasonable objection, in itself, to a moral theory. Rather, 'value is complex' is a universal reason to be less confident about all theories. (No theory, no matter how complex, is immune to this problem, because value might always turn out to be even more complex than the theory suggests.) To suggest that your moral theory is more likely to be correct than a simpler alternative merely because it's more complicated is obviously wrong, because knowing that value is complex tells us nothing about how it is complex.

In fact, even though we know that value is complex, a complicated theory that accounts for the evidence will almost always get more wrong than a simple theory that accounts for the same evidence -- a more detailed map can be wrong about the territory in more ways.

Again, morality doesn't behave like science.

Interestingly, in all the above respects human morality does behave like any other empirical phenomenon. The reasons to think morality is complex, and the best methods for figuring out exactly how it is complex, are the same as for any complex natural entity. "Looking for general laws" is a good idea here for the same reason it's a good idea in any scientific endeavor; we start by ruling out the simplest explanations, then move toward increasing complexity as the data demands. That way we know we're not complicating our theory in arbitrary or unnecessary ways.

Knowing at the outset that storms are complex doesn't mean that we shouldn't try to construct very simple predictive and descriptive models of weather systems, and see how close our simulation comes to getting it right. Once we have a basically right model, we can then work on incrementally increasing its precision. As for storms, so for norms. The analogy is particularly appropriate because in both cases we seek an approximation not only as a first step in a truth-seeking research program, but also as a behavior-guiding heuristic for making real-life decisions under uncertainty.

I also think the reasoning in this example is bad for general reasons, namely moral heuristics don't behave like scientific theories: falsifying a moral hypothesis doesn't mean it's not worth considering.

Then again, the same applies to scientific theories, so long as the old now-falsified theory is a good approximation to the new currently accepted theory within certain ranges of conditions (e.g. classical Newtonian physics if you're much bigger than an atom and much slower than light).

The original statement of my heuristic for deciding moral worth contained the phrase "in principle" which was meant to cover cases like this. A human in a contingent circumstance (e.g. extremely socially inept, in a coma) that prevents them from participating in human society is unfortunate, but in possible worlds very similar to this one they'd still be capable of participating in human society.

Isn't a quasi-Aristotelian notion of the accidental/essential or contingent/necessary properties of different species a rather metaphysically fragile foundation for you to base your entire ethical system on? We don't know whether the unconscious / conscious distinction will end up being problematized by future research, but we do already know that the distinctions between taxonomical groupings can be very fuzzy -- and are likely to become far fuzzier as we take more control of our genetic future. We also know that what's normal for a certain species can vary wildly over historical time. 'In principle' we could provide fish with a neural prosthesis that makes them capable of socializing productively with humans, but because our prototype of a fish is dumb, while our prototype of a human is smart, we think of smart fish and dumb humans as aberrant deviations from the telos (proper function) of the species.

It seems damningly arbitrary to me. Why should torturing sentient beings be OK in contexts where the technology for improvement is (or 'feels'?) distant, yet completely intolerable in contexts where this external technology is more 'near' on some metric, even if in both cases there is never any realistic prospect of the technology being deployed here?

I don't find it implausible that we currently use prototypes as a quick-and-dirty approximation, but I do find it implausible that on reflection, our more educated and careful selves would continue to found the human enterprise on essentialism of this particular sort.

I also think the reasoning in this example is bad for general reasons, namely moral heuristics don't behave like scientific theories: falsifying a moral hypothesis doesn't mean it's not worth considering.

Actually, now that you bring it up, I'm surprised by how similar the two are. 'Heuristics' by their very nature are approximations; if we compare them to scientific models that likewise approximate a phenomenon, we see in both cases that an occasional error is permissible. My objection to the 'only things that can intelligently socialize with humans matter' heuristic isn't that it gets things wrong occasionally; it's that it almost always yields the intuitively wrong answer, and when it gets the right answer it seems to do so for overdetermined reasons. E.g., it gets the right answer in cases of ordinary human suffering and preference satisfaction.

in general I am skeptical of people who claim to have useful moral heuristics that don't fail on weird edge cases

I agree that someone who claims an unrealistic level of confidence in a moral claim as an individual deserves less trust. But that's different from claiming that it's an advantage of a moral claim that it gets the right answer less often.

I'm skeptical of the claim that any fish have societies in a meaningful sense.

I just meant a stable, cooperative social group. Is there something specific about human societies that you think is the source of their unique moral status?

If they're intelligent enough we can still trade with them, and that's fine.

If we can't trade with them for some reason, it's still not OK to torture them.

The psychological unity of mankind still applies here: any human from one civilization could have been raised in the other.

'The psychological unity of mankind' is question-begging here. It's just a catchphrase; it's not as though there's some scientific law that all and only biologically human minds form a natural kind. If we're having a battle of catchphrases, vegetarians can simply appeal to the 'psychological unity of sentient beings'.

Sure, they're less unified, but how do we decide how unified a unity has to be? While you dismiss the psychological unity of sentient beings as too generic to be morally relevant, the parochialist can step up to dismiss the psychological unity of mankind as too generic to be morally relevant, preferring instead to favor only the humans with a certain personality type, or a certain cultural background, or a certain ideology. What I'm looking for is a reason to favor the one unity over an infinite number of rival unities.

I should also reiterate that it's not an advantage of your theory that it requires two independent principles ('being biologically human', 'being able to (be modified without too much difficulty into something that can) socialize with biological humans') to explain phenomena that other models can handle with only a single generalization. Noting that value is complex is enough to show that your model is possible, but it's not enough to elevate it to a large probability.

I don't know why you got a down-vote; these are good questions.

What about unconscious people?

I'm not sure there are unconscious people. By 'unconscious' I meant 'not having any experiences'. There's also another sense of 'unconscious' in which people are obviously sometimes unconscious — whether they're awake, aware of their surroundings, etc. Being conscious in that sense may be sufficient for 'bare consciousness', but it's not necessary, since people can experience dreams while 'unconscious'.

Supposing people do sometimes become truly and fully unconscious, I think this is morally equivalent to dying. So it might be that in a loose sense you die every night, as your consciousness truly 'switches off' — or, equivalently, we could say that certain forms of death (like death accompanying high-fidelity cryonic preservation) are in a loose sense a kind of sleep. You say /pəˈteɪtəʊ/, I say /pəˈteɪtoʊ/. The moral rights of dead or otherwise unconscious people would then depend on questions like 'Do we have a responsibility to make conscious beings come into existence?' and 'Do we have a responsibility to fulfill people's wishes after they die?'. I'd lean toward 'yes' on the former, 'no but it's generally useful to act as though we do' on the latter.

So what's your position on abortion?

Complicated. At some stages the embryo is obviously unconscious, for the same reason some species are obviously unconscious. It's conceivable that there's no true consciousness at all until after birth — analogously, it's possible all non-humans are zombies — but at this point I find it unlikely. So I think mid-to-late-stage fetuses do have some moral standing — perhaps not enough for painlessly killing them to be bad, but at least enough for causing them intense pain to be bad. (My view of chickens is similar; suffering is the main worry rather than death.) The two cases are also analogous in that some people have important health reasons for aborting or for eating meat.

My brain is certainly an example of a brain that I prefer not be in pain, though not the only example.

My confidence that brain B manifests a mind that experiences pain and suffering given certain implementation (or functional, or phenomenological,or whatever) details depends a lot on those details. As does my confidence that B's mind antiprefers the experiential correlates of those details. I agree that there's no strict entailment here, though, "merely" evidence.

That said, mere evidence can get us pretty far. I am not inclined to dismiss it.