On a mises.org forum, one author wrote the following:
The intimation of [an article by David Gordon] is that the facts of moral realism are embedded into the very structure of the Universe at a level transcending humanity itself. But there is no reason to believe this is actually the case. What we observe is that the conditions for moral facts reside entirely within the human social order. That is, morality is not a question that has anything to do with the Absolute or the Universe as it would appear to an omniscient being.
Rather, moral facts are facts merely about the human social order, about human nature. They are facts about human brains, human bodies and terrestrial biology and our terrestrial environment and the particular facts of our situation in this corner of the cosmos. Is it immoral for Martians to kill Martian children? I have no idea. But I know that it is immoral for humans to kill human children. That's because I know the facts about human beings relevant to human morality but I don't know the facts about Martians relevant to Martian morality.In other words, morality is not absolute. It's something that can be discovered by observing human society. Later, the author explained that we can observe how human societies function (and human nature in general) and derive from those observation the rules of ethics -- rules of how to achieve satisfaction for a human being.
So, for instance, "human beings like company of others; human beings do not like to keep company with people who annoy them; if human beings want satisfaction in their lives, they should not be annoying to other human beings" (obviously, among other things). In this sense, being an annoying person in unethical, but being a nice person is ethical.
In all my conversations with atheists, this was basically their description for "G-dless" basis for morality.
As I see it, morality needs to be on the one hand applicable to the individual (you can't make a moral prescriptive statement that addresses the needs or goals of a society, since it is the individuals who make choices) and on the other hand universal (we can't say that a serial killer acts morally, since his actions bring him the greatest satisfaction). What's left then? It seems to me that what's left is precisely the Absolute Moral Truth -- applicable to individuals but regardless of their individual preferences. If adultery is wrong it's wrong for everyone and always.Obviously, one can define "morality" as "a set of rules to achieve satisfaction". (You can define morality as whatever you want -- for instance, "eating meat from time to time"; in that case, a vegetarian is acting immorally.) Therefore, if you are like most people in that you like company of others and it is true that (most of the) people around you don't like jerks, it is immoral to act like a jerk.
(Of course, there can be built-in conditions. Lying is wrong, but lying to save someone's life is right, since saving life takes moral priority.)
It also seems to me that libertarian morality is based on the assumption that nothing changes between two people existing in a state of nature and them existing in a society. To see whether something is wrong or not, we have to ask: would it be OK for me to do that to you on a deserted island? For instance, would it be ok for me to steal from you, when there is no society around us? If not, then why is it ok for me to steal from you when there is a society, with the society's help?
But if there is no Absolute Moral Truth, then, indeed, why is it wrong for me to rob you when we are alone on a deserted island if I calculate that it is a greater benefit for me to do that than co-exist with you peacefully? Also, if my actions even in a society are secretive enough, I can get away with doing them without changing the society itself. So, one can say: "people's happiness will be the greatest if they live in a society where children are not killed". But what does this have to do with me personally making a decision whether or not to kill a child secretly? Presumably my actions do not affect the society I live in. Also, while a law against child killing (that benefits the society) could exist on a societal level (applicable to all citizens, enforced by all law agencies of the society), it would still not be a moral law, since it would say nothing as to why I need to keep it at all times and in all circumstances.
I have once heard a joke: If you're stranded on a deserted island with limited food and water in a company of either an atheist or a statist, you should kill them immediately, for your life is in danger. Neither of them can conceive of what is moral or right outside of the society. If they are sufficiently liberated from the traditions of their upbringing, they will reason the justification for killing you very easily.
But what happens if you don't care about the company of others, but it gives you satisfaction to cause misery to others? Then it suddenly turns out that acting like a jerk is not immoral for you. As I said, you can define morality whichever way you want, but I just don't think that this fits most people's innate understanding of morality.