Velleman says that, if we came across a new species without religious beliefs, "we would be perfectly astounded...if they had come up with the ten commandments." On the other hand, he says, we would have expected them to have discovered the idea of reciprocity, so "we would not be at all astounded to find that the inhabitants of Planet X had discovered the Golden Rule".
I think this involves an equivocation on what the discovery of reciprocity would be. Obviously in some sense they would have had to discovery reciprocity since they would have to be able to engage in some sort of social interaction. But this is a long way from a Golden Rule. All one really needs for this sort of reciprocity is a general sense of exchange, which can easily enough be capsulated in a plethora of positive laws and customary rules of etiquette, without any Golden Rule at all. Much more likely, I think, would be laws and manners, of a very ordinary sort, and any sense of reciprocity would be encoded in precise rules about hospitality or honor or what have you. Going beyond this is actually a surprising thing, and not generally to be expected. To do so one needs at least the minimal recognition that the laws and manners don't ground reciprocity but are grounded in it. And when one has gotten this far, one still doesn't have a Golden Rule; one has what is sometimes called a Silver Rule, which goes beyond laws and manners primarily by requiring restraint. The Golden Rule, however, is a very strong principle; except in a perspective that involves a very robust notion of moral order and authority, I don't think it is particularly obvious that it is even right.
So the end result is that we should expect something much more like the Decalogue, and much less like the Golden Rule. The Golden Rule is actually fairly rare even among human beings; why should we expect it to be common knowledge among aliens, however advanced? One can do without it; it has practical ramifications, but its value has largely been metaethical. But the Ten Commandments are basically about setting the actual boundaries of respect -- respect God, respect parents, respect others in society -- and just give some specifications of these. A society would be much more likely to have something like this.
But the issue was, I think, supposed to be what used to be called the First Tablet: the commandments that deal in one way or another with God. Clearly a species that had no belief in God would not have such a commandments; and the idea, I think, is that they would still have a notion of the transcendence of moral truths. I find this rather doubtful, as well. Consider the passage quoted from Dennett:
But it would still be arithmetic. Now, we can say: "And would it share ethical principles with us?" And I think, in some regards, "Yes, it would." Now, does that make those principles transcendent? Yeah.
But this seems mere semantics, taking 'transcendent' as just a synonym of 'able to be found everywhere'; as, I suppose, dust particles are transcendent, or force-vectors are transcendent, or energy is transcendent. The idea seems to be that they would be true in any universe, and so surpass any particular universe; but they really don't surpass anything in virtue of being true everywhere -- if one can even legitimately talk about them being true anywhere. They're just true, end of story, and the question is why this should be considered as particularly important. Usually by 'transcendent' we mean something that surpasses the categorical. What is transcendent about the universality of arithmetic? How in the world could the universality of ethical principles give them 'transcendence'? The reason we associate math and morals with transcendence is the perfectly straightforward reason that historically they became associated with what was deemed a higher order of reality: the divine -- either gods or something, as Platonists have at various times said, more divine than mere gods, something even gods have to respect as more fundamental than they are. The truths were regarded as transcendent because they were caught up in something that is immensely greater than us and the ordinary things we could know. And I think this move was a fortunate one, since I think they are caught up in something immensely greater than us, something that is, as it were, more real and fundamental than the rest. But one has to be trained to see it. There are lots of people who never do. There are societies that have functioned perfectly well without ever seeing it. An atheist trained to see it may, in seeing it, come to be a theist; but there is simply no reason whatsoever to think that any atheist would see it in a culture where it had never previously been associated with something that genuinely transcends ordinary limits, like a god or a divine order or a higher level of reality.
For that's precisely the trouble: math and morals can just as easily be treated as ordinary, and they often have been. I see no reason why a society can't Humeanize them and do just fine. They would lose something, to be sure; they would lose what some of us regard as their religious associations, and what others regard as their superstitious associations. But to see math or morals as transcendent requires seeing that they involve or are involved in something extraordinary, something that can't be boxed up into ordinary categories. It would not strictly have to be a personal deity; but there is every reason to think that it would have to be the sort of thing we tend to call divine. And any talk of the transcendence of mathematical or moral truth is either fuzzy-talk or is a borrowing, direct or indirect, from this. Close the age of God and you close the age of Transcendent Truth. You still have truth, and that will get you some way. But it will not get you anything transcendent, unless you have already been trained to see it in that light. And that presupposes being trained to see it as part of a higher order, either of gods or of something more divine than any mere gods. How anyone could recognize this without any notion of divinity, or something closely analogous, is anyone's guess.
Of course, if one just means by 'transcendent' something like 'universal', one could just say so, and skip all the nonsense about their being transcendent.
But, as I said, it's a good post, and worth reading.