Some thoughts on the moral argument
I'm greatly looking forward to Jerry Walls and David Baggett's forthcoming book Good God: The Theistic Foundations of Morality. I have always thought that C.S. Lewis was right to center his apologetic in Mere Christianity on the moral argument, because the voice of conscience seems to be a particularly appropriate way for a personal God to reveal Himself. Here are just some of its strengths:
1. Obligation is a relationship that obtains between persons, so we would expect the Christian God to penetrate our awareness through our sense of moral duty.
2. Conscience is a divine communication channel that is widely accessible: even if people cannot appreciate the subtleties of a metaphysical argument for God's existence, they can certainly hear the still, small voice urging them to do right, to follow the way of life and wisdom.
3. The existence of a genuine, objective moral order in the universe would be very hard to square with atheistic naturalism. It is not the sort of thing that could come into existence by naturalistic methods. At best naturalistic methods could produce the kind of tentative, transient, spontaneous forms of social cooperation observed among primates and other mammals, but which are a far cry from the robust, universal moral order sensed by reflective human beings. That sort of thing could only arise by intention.
It is commonly objected that if there were some sort of moral law pushing people to act in certain ways, there should be more consensus on its content than we in fact observe. Isn't there a good case to be made for cultural relativism, in which case the moral argument would lose its force? If morality resembled the rules of football more than the force of gravity, atheists would have no cause to be uneasy about the pangs of conscience. C.S. Lewis thought that actually there is a lot of cross-cultural consensus on the content of the moral law, and he collected an impressive list of supporting testimony. But even granting the existence of genuine disagreement over the content of at least some aspects of the moral law, the force of the argument seems to derive mostly from the observation that there seems to be a moral order to the universe, whatever the actual contours of that order. Of course the most effective way to bring people to recognize the moral law is usually to challenge them with some paradigm instances of the law, such as 'It is wrong to torture babies for fun'. But we do not have to describe the law accurately in every detail or agree on all its components in order to recognize its existence, which is incompatible with atheistic naturalism.
Another, more recent challenge to the argument comes from evolutionary theory. Some authors suggest that human morality is no different from the kinds of tentative, transient, spontaneous forms of social cooperation (and antagonism), driven by what Adam Smith called the 'moral sentiments' (such as empathy, loyalty, reciprocity, etc.), that we also observe in various primate and other species. If the argument is to get off the ground, a case must be made that our experience of moral obligation goes beyond what can be accounted for by assuming that human morality is only primate morality augmented by our reflective capacities. However, the empirical finding that human beings are driven by evolutionarily sculpted moral sentiments does not challenge the moral argument in the slightest. That would only be the case if we were to assume a radical non-cognitive understanding of the emotions, in which the passions are always the antithesis of reason, or at least have nothing to do with it. But it is far more reasonable to think that emotions are always directed toward our beliefs and projects, and in fact put us in contact with reality in subtle, powerful ways. For example, the feeling of hunger alerts us to our need for food, while the disgust that we feel at the thought of child pornography signals a violation of the moral order. The truth is that human beings are passionate creatures. We are motivated by strong emotions and feelings, and feelings are 'natural signs' that put us in touch with the realities around us. In light of this, the fact that our moral sentiments evolved does not defeat our sense of the objectivity of the moral order. On the contrary, they put us in touch with that order.