surely there's a causal relation between humans' instantiating the computation and Eliezer's referring to it.
Of course there's a causal relation which explains the causal fact of this reference, but this causal explanation is not the same as the moral justification, and it's not appealed to as the moral justification. We shouldn't save babies because-morally it's the human thing to do but because-morally it's the right thing to do. What physically causes us to save the babies is a combination of the logical fact that saving babies is the right thing to do, and the physical fact that we are compelled by those sorts of logical facts. What makes saving the baby the right thing to do is a logical fact about the subject matter of rightness - in this case, a pretty fast and primitive implication from the premises that are baked into that subject matter and which distinguish it from the subject matter of wrongness. The physical fact that humans are compelled by these sorts of logical facts is not one of the facts which makes saving the baby the right thing to do. If I did assert that this physical fact was involved, I would be a moral relativist and I would say the sorts of other things that moral relativists say, like "If we wanted to eat babies, then that would be the right thing to do."
Of course there's a causal relation which explains the causal fact of this reference, but this causal explanation is not the same as the moral justification, and it's not appealed to as the moral justification
Of course it isn't, because we're doing meta-ethics here, and don't yet have access to the notion of "moral justification"; we're in the process of deciding which kinds of things will be used as "moral justification".
It's your metamorality that is human-dependent, not your morality; see my other comment.
On Wei_Dai's complexity of values post, Toby Ord writes:
The kind of moral realist positions that apply Occam's razor to moral beliefs are a lot more extreme than most philosophers in the cited survey would sign up to, methinks. One such position that I used to have some degree of belief in is:
Strong Moral Realism: All (or perhaps just almost all) beings, human, alien or AI, when given sufficient computing power and the ability to learn science and get an accurate map-territory morphism, will agree on what physical state the universe ought to be transformed into, and therefore they will assist you in transforming it into this state.
But most modern philosophers who call themselves "realists" don't mean anything nearly this strong. They mean that that there are moral "facts", for varying definitions of "fact" that typically fade away into meaninglessness on closer examination, and actually make the same empirical predictions as antirealism.
Suppose you take up Eliezer's "realist" position. Arrangements of spacetime, matter and energy can be "good" in the sense that Eliezer has a "long-list" style definition of goodness up his sleeve, one that decides even contested object-level moral questions like whether abortion should be allowed or not, and then tests any arrangement of spacetime, matter and energy and notes to what extent it fits the criteria in Eliezer's long list, and then decrees goodness or not (possibly with a scalar rather than binary value).
This kind of "moral realism" behaves, to all extents and purposes, like antirealism.
I might compare the situation to Eliezer's blegg post: it may be that moral philosophers have a mental category for "fact" that seems to be allowed to have a value even once all of the empirically grounded surrounding concepts have been fixed. These might be concepts such as "would aliens also think this thing?", "Can it be discovered by an independent agent who hasn't communicated with you?", "Do we apply Occam's razor?", etc.
Moral beliefs might work better when they have a Grand Badge Of Authority attached to them. Once all the empirically falsifiable candidates for the Grand Badge Of Authority have been falsified, the only one left is the ungrounded category marker itself, and some people like to stick this on their object level morals and call themselves "realists".
Personally, I prefer to call a spade a spade, but I don't want to get into an argument about the value of an ungrounded category marker. Suffice it to say that for any practical matter, the only parts of the map we should argue about are parts that map-onto a part of the territory.