Is there a universal standard for moral conduct?
The trouble with morality is that most people will answer that question: "Yes, and my standard of moral conduct is it." And this would be all well and good, except that people disagree as to what that universal, unassailable moral standard actually is. (I could draw examples from any two religious texts of conflicting moral standards if I wanted to make this post a lot more inflammatory than it is.) Moral codes usually overlap to the point that we can gloss over the differences, but that doesn't mean that they aren't there, and it's troubling to think that morality can be so arbitrary.
If I find myself in the market for a set of moral precepts, what should I look for? I don't just want some rules that were set out arbitrarily; I need something a little more reliable than that. Something that can be derived from first principles would be ideal. Unfortunately, as far as I know this has never been done. The closest thing I can think of is Kant's Categorical Imperative: "Act only according to that maxim whereby you can at the same time will that it should become a universal law." As moral principles go, it's a decent one, but it's not especially helpful when comparing moral systems. It tries too hard to justify what you already believe. If you truly, in your heart, believe that witches must be stoned to death, and would feel the same way even if you were found to be a witch, then the Categorical Imperative insists that you stone that witch to death.
But I digress. Can we find a system of ethics that depends neither on unjustified commandments, nor on preexisting moral beliefs?
Evolutionary ethics and group selection provide an interesting framework for looking at morality. The theory here is that certain types of ethical systems give societies an advantage over others. Thus, behaviors which may not help the individual, such as altruism, can still arise through evolution, by sustaining the society the individual lives in. And, conversely, unethical behavior is considered such because it harms society in some way. (Doesn't this presuppose that evolution happened? Well, yes. Evolution is obvious enough by now that no honest person can deny it.)
This would explain a lot of features of moral systems. Killing others is generally considered bad, because it obviously weakens society. Stealing from others is generally considered bad, because having property rights enforced allows for commerce, which strengthens society. Moral systems ofthen also have an element of self-preservation built in, which makes a lot of sense in an evolutionary framework. Evil people and heathens are those who don't follow the system; eliminating the evil people in a society strengthens the moral system itself.
This also offers up at least three possible explanations of the large degree of overlap between moral systems. First, there could be a common ancestor of moral systems which was gradually spread all over the world. Second, there could be convergent evolution at work, and different moral systems could eventually end up with the same, or very similar, core values. Third, the fact that very different moral systems are labeled "evil" could imply that systems that were radically different were stomped out by their neighbors, once a dominant type of system emerged. Most likely, all three of these have played some role.
The Role of Law
These days there's a degree of mixing of culture which is unprecedented in the history of humanity, and this has serious implications for moral systems. Back when you could reasonably say that everybody in a given tribe/city/fiefdom/whatever followed the same moral strictures, things worked more or less smoothly. These days, we can make no such assumptions; how can we enforce a basic standard of morality?
I theorize that the law, whatever it may be at the time, forms a sort of meta-morality at the intersection of whatever moral systems are dominant at a given time. This can only work because most systems of morals agree on almost all of the core tenets of morality: don't kill, don't steal, don't be a jerk, etc, etc. There are various benefits to having an established moral system, but many of the benefits require everybody in a region to follow the system, and law provides just such a regionally-bound framework.
Then, the law isn't just a desirable thing - a strong, and absolutely secular, legal system is the thing which makes an extremely diverse society like ours functioning. It is not, however, a substitute for a moral system, for two reasons. First, the law is made with plenty of input from individuals who seek to alter it to their own benefit. While it would be nice to have a system of laws which corresponds exactly to morals, such a thing is simply not possible. Second, laws cannot evolve over time in the same way that current moral systems did. The law, rather than being a complete moral theory, is only useful as a bridge between the moral beliefs of individuals.
Unfortunately, all this is fun to think about, but it still leaves me in the dark as to which ethical precepts to stick to. Ah, well, maybe I'll have better luck some other time. The default course of action, of course, is to just follow what everybody around me is doing, and while this line of thinking hasn't led to anything more useful than that, it has at least given some kind of justification to the default.