[Projoy] I knew someone was going to say that.

[Darren] Yayy! Thank you. By the way, I inexplicably can't access this page (alone of all in the Morniverse) from work any more, it seems, which is why I fell silent. Bear in mind that even moral statements are not propositions, it does not necessarily follow that they are not universally applicable. "Don't murder!" could be normative for everyone even though it does not express an objective fact. Perhaps there could be "objective commands". But what those could be, and how they could be, I don't know, and explaining them is a task for someone else.
[Raak] You surely know that your gravity analogy doesn't apply! Floating ships and space probes aren't "breaking" the law of gravity any more than I am when I hold my leg in the air before taking a step. Rather, the law of gravity is simply one of many physical laws which are inter-related, or interact. But that's beside the point. More to the point is that even the list you link to contains much that is arguable. I, for example, don't set much stock by "duties to ancestors" even though the average Confucian might regard it as a central moral imperative. There is nothing that has been universally accepted as a moral imperative, and even if there were, it wouldn't prove anything other than that people all thought it was right. The most such things can show is that human beings have evolved - either biologically or socially - to think that certain things are right or wrong, presumably because those who didn't think this didn't develop stable societies. Thus most people think that murder is wrong because if they didn't they wouldn't have survived. We can therefore explain moral imperatives - or at least their basic outlines - quite adequately in a historical or evolutionary way, without needing to posit that moral views express some kind of "truth" about the world. And the sorts of questions that Projoy asks indicate that there are big problems with the view that they do. After all, there are many people who think that there are moral facts, but no-one seems able to agree what they are. Is abortion a fundamental right or is it one of the blackest crimes there is? The fact that people disagree doesn't prove that there isn't a matter of fact at dispute, of course, but it does raise the question - how, even in principle, could the dispute be settled? What "evidence" (even if in practice it could not be collected) would prove it one way or the other?
Another point that might be relevant - the Tao website states that "For those who do not perceive its rationality, even universal consent could not prove it." Well, I'm afraid I don't perceive its rationality. I may perceive its utility or practical application. But David Hume pointed out that morality isn't to do with rationality, and vice versa - he said something like "There is nothing irrational about my preferring the destruction of the entire universe to the scratching of my finger," and he was right - such a preference may be morally wrong in whatever sense you have of the word, or it may be highly unuseful, but it's not, strictly speaking, irrational.

[Projoy] Self-interest is at work in stepping out of the path of a car, but that doesn't make it subjective in any useful sense. Everyone will step out of the way of that car, except only children who have not yet learned that it is dangerous, the drug-addled, and the suicidally depressed. This is only subjective to the degree that every thought we have is subjective. What is objective is that the car will kill you if you don't get out of the way. Opinions and wishes are irrelevant. Reality is like the Terminator: you can't reason with it, you can't argue with it. You only have power to choose your actions, not their consequences.
       (Repeat earlier caveat that I'm taking this horse out for a ride to test its legs.)
       Thus it is with morality. The enlightened do good and avoid evil, because, from their point of view, the first person that good acts benefit and evil acts harm is oneself, consequences as undeniable as traffic. It applies to everything from not mugging old ladies for their pension money to getting out of bed in the morning. The idea has a long pedigree, e.g. Socrates and the Buddhist canon (and in a debased form in the Religions Of The Book, where all the consequences are deferred to a supposed later life, despite the statement by one of their prophets that "the kingdom of heaven is within you"). It doesn't give instant answers to all questions, any more than the laws of physics will immediately tell you how to build a kilometer-tall skyscraper.

[Bm] You give two arguments that undercut each other: that there are no universally accepted moral principles, and that universally accepted moral principles arise for evolutionary reasons. You can't have it both ways, but I'll ride this horse over both of them anyway.
       No scientific truth is universally accepted either, if you define "universally" narrowly enough. There are, nonetheless, substantial areas of agreement on moral issues that can be found throughout all civilisations. That doesn't prove they are true (as Lewis himself says), merely that they exist. Perceiving their truth is a separate matter.
       I could take the evolutionary explanation as evidence on my side -- the consequences of right and wrong action are exactly your presumed evolutionary pressures. Not getting run over is also evolutionarily adaptive, but that does not mean that personal decisions and the laws of physics have nothing to do with it.
       How do you perceive the utility of the Way? If it is useful to follow the Way, what is it useful for? And what in turn is that useful for? Utility offers no foundation. Likewise rationality. Look hard enough, and all attempts to find foundations lead only to an infinite regress. Ideas can only justify ideas in terms of other ideas. Morality is about actions, and actions cannot be deduced from thoughts, any more than an ought from an is.
       Hume also claimed not to see causation, but he wouldn't have survived to write his books if he hadn't dodged horse-drawn carts now and then.

[Raak] Maybe Hume was just very, very lucky.

[Raak] Your supposition that evil acts harm the doer is where it all falls down for me. Sort of repeating Bm's point, but a car will run people down according to the laws of physics, which can be reliably shown to operate universally (at least as far as we can observe), but mugging someone for their pension cannot be shown universally to have negative effects for the individual (unless you start invoking some unknowable afterlife or karma or whatever). In other words, some people get away with breaking moral rules, in just the way that a car can't get away with braking the rules of physics in order to save a life. There is merely a certain probability that a system of law exists that will make mugging disadvantageous to the perpetrator. This is not 100% (in fact taking human history as a whole, I'm tempted to speculate it is less than 50%). Is there any real evidence whatsoever to the contrary?