I've been thinking a lot about morality lately, and here are some conclusions that I have come to.
The root of morality is concern for the well-being of other people. This is the only clear definition of morality I have found which matches our use and intuitions about the word. A truly moral concern for other people is not valuing people because of what they can do for you or because caring for other people fulfills some selfish desire on your part. Rather, a moral concern for other people is valuing people for their own sake.
We've all heard the saying "The buck stops here." We often value things because of deeper values that we hold. For example, I value Subway sandwiches because of the pleasure I get from eating them. Why do I value pleasure? Is there some reason to value pleasure? No. The buck stops there. Pleasure is a basic, primary desire (or value).
Likewise, if you ask yourself why you value other people, there are only two possible answers you can come up with: Either "the buck stops there" and valuing other people is one of those basic desires you have, or you value other people because of some deeper, more basic desire you have. If you value other people for some deeper desire, then what, we may ask, might that desire be? Is that desire a selfish desire or an unselfish one? Since an unselfish desire is, by definition, a desire that values other people, then it wouldn't make any sense to say that you value other people because of a more fundamental desire to value other people.
So if you value other people because of some other desire that you have, then you could only be doing it because of a selfish desire (so that you won't go to prison, let's say). If that's true about you, then are you really moral? I mean, if a criminal decides not to commit a crime because he's being video-taped at the moment, could we really call such a person moral? He did the right thing by not committing the crime, but it was for the wrong reasons. Such a person is immoral. On the other hand, someone who chooses not to commit a crime, even when they know that they can get away with it, because they want to avoid the damage it will cause other people, is a moral person.
William Lane Craig, I think, spends much of his philosophizing about morality thinking about arguing with a hypothetical extremist moral skeptic (someone who doesn't believe in morality). Craig deeply wants (I might even say needs) for morality to be grounded in something higher than animal minds. The moral skeptic may point out that he has his opinions, and his desires, and we have ours, and by what authority could one claim that one is better than the other? That one is right and one is wrong? Craig's answer, I think, is that his morality is endorsed by God, an infinitely great and wise being, and that settles the whole issue. Craig seems to believe this is the only answer possible, or that it is at least the best answer anyone has come up with so far, therefore that means that his answer is probably correct. Since his answer includes the existence of God, we must conclude that God exists.
In reality, there is no way at all to answer the moral skeptic. What does it mean for something to be better than something else? When something is better than something else, it satfisfies some assumed goal. Example: I may be a better swimmer than anyone else in my family, if by "better at swimming" we meaning faster which is essential just saying that my swimming satisfies the goal of speed more fully than any other member of my family. When the moral skeptic asks "Why is your set of opinions better than mine?" What end goal is, or could he, be talking about? If he is asking why valuing others actually works to help other people, then it is quite obvious how could be answered. And if the happiness of other people is not among his set of end-goals, then he could only be asking how valuing other people would help him. Well, there are benefits to behaving in a way that shows value (staying out of prison, creating enjoyable friendships, and so on) But if the moral skeptic only acts like he values other people in order to recieve those benefits (staying out of prison, friendship, etc.) and he does not really and truly hold the happiness of others amongst his basic values, then he is not, and can not, be moral, as we have established earlier.
Nor can we persuade the moral skeptic to adopt the happiness of others amongst his basic values. For the only way you can persuade someone to do anything is by appealing to values which they already hold to. Think about it: when have you ever convinced something that they ought to do something without showing them how it fulfills their goals? How could you? Further, Richard Carrier and Alonzo Fyfe have both (independently, I think) proposed that the word "ought" simply designates what must be done in order to fulfill an assumed desire (example: If you want to eat a good hamburger, and McDonald's sells good hamburgers, then you ought to go to McDonald's). Since I believe that they are correct, that makes the statement that "one cannot persuade anyone without appealing to values they already have" true by definition.
Now, since we can't get the moral skeptic to be really and truly moral by appealing to his selfish values, and since the moral skeptic, if he really is one, has no unselfish values, then it follows that the moral skeptic cannot be persuaded. This conclusion is logically necessary, as it follows from the premises, and the premises, as I have argued, are indisputable. And notice that this conclusions makes no reference to theism or atheism. The conclusion applies regardless of which position one takes, which means that Craig cannot claim that his moral system is greater in light of its being able to answer the moral skeptic, because it can't.