Why should one be moral? Regardless of what ethical system is correct (if there are any), I haven't come across an adequate explanation for why one should act in a morally virtuous manner. It seems to me that though almost all ethical theories implicitly claim that one should always act moral if possible, there is never an explanation why. If one were to claim that acting in a morally virtuous manner will likely improve the satisfaction/happiness/etc. in your life, then it seems that this pragmatic reasoning can allow for someone to act in a morally vicious manner (as long as they are happy). Ultimately, it appears that what I am asking is the following: what reason will I have to value moral obligations over my own desires and satisfactions? Is it even sensible to ask such a question? An analogy can be made with the value of reason: if you have no goal in knowing the truth, valuing reason in that regard will be pointless. So what goal would correspond to morality (if that makes sense)?

Good question(s). A range of philosophers have sought to argue that one should be moral out of self-interest. Some philosophers who argue that morality must lead to fulfillment (the virtuous should be happy) combine their ethics with a moral argument for God. Kant thought that for morality to make sense we need to have a kind of moral faith in God as an ideal judge who will insure that the good are rewarded, and the vicious are not. Still other philosophers will question the intelligibility of your question: asking why one should be moral may be likened to asking you should do what you should do. Questions like 'why is the sky blue' make sense, whereas 'why is blue, blue?' do not.

I recently had an argument in an epistemology class about the relationship between facts and human minds. I argued that a fact cannot exist until a human mind knows it. Most of the rest of the class (and the professor) argued that facts can exist independently of human minds. My professor's example: Every human being believes that the world is flat, when it is in fact round. I argued that the fact that the world is round did not exist until someone thought it. Can a fact exist without a human mind?

You are adopting a pretty radical position, for it seems like common sense for us to recognize as facts (or truths or as actual states of affairs) all sorts of things quite independent of human minds. Most of us would want to say (for example) that it was true that there was life long before there was intelligent life here on earth. Your professor's example is a little odd, partly because very few people have ever believed the earth is flat. (There is a good book on the myth of believing in a flat earth). But you might be able to defend your position as part of a philosophy of language, contending that facts are what correspond to or are referred to as sentences and simply hold the line about not recognizing facts until you have language-users. I believe Fred Stoutland holds that position, and Richard Rorty expresses something like that in The Mirror of Nature. Still, you are not in an enviable position in terms of arguments, as most of us would want to recognize that it is a fact that before there...

I recently had a conversation with a friend who is convinced that morality is simply a human invention, no more than a system of social conventions developed to ensure social stability and ultimately the propagation of the human species. Do you agree? If not, can you outline any arguments for morality being something more than just social convention? For example, are there any arguments for morality as something independent of humans, something which exists objectively, "out there", and does not depend for its existence on our conceptions of it, or our development of its principles?

No, I do not think that morality is only a matter of social conventions, no more so than sickness or health. It seems to be an objective (and perhaps even common sense) fact that cancer is bad for a human being, and I think we may similarly see that rape is a wrongful violation of a person. Building on such apparent facts, one can offer what is called a natural law account of morality, in which morality can be defined (or recognized) in terms of what contributes to the flourishing or destruction of human nature. A natural law approach to morality is not the only alternative, however, for seeking to ground moral judgments. One may adopt a form of utilitarianism or Kantianism, for example. I prefer to combine a natural law account with an account of moral reasoning that highlights impartiality, an affective appreciation of the points of view of others and an awareness of all relevant facts upon which to form moral judgments. Treating morality is only a matter of human conventions seems unable to...