Apologists are fond of running the moral argument. The most popular version goes something like this:
P1: Objective moral values exist only if God exists
P2: Objective moral values do exist
Conclusion: Therefore, God exists
The argument doesn’t necessarily commit one to divine command theory, but most theists are divine command theorists. Objective moral values are identical with God’s moral nature and are then embedded in divine commands. This is alleged to be the only viable ontological basis for objective moral values. I am not going to rehearse the familiar responses to divine command theory. Some, such as Robert Adams’, are quite sophisticated and I can’t do justice to them here. However, I think a parallel to divine command theory can be found in the old doctrine of the divine right of kings. Obviously, nobody in the contemporary West believes in the divine right of kings anymore. It’s this fact makes it particularly illustrative for my purposes.
Consider the following argument:
P1: Political legitimacy only exists if God exists
P2: Political legitimacy does exist
Conclusion: Therefore, God exists
This reasoning could be readily used to establish the divine right of kings. Kings derive their authority and political legitimacy from God. However, in the contemporary West, most people, including theists, would reject the first premise. There might be some who claim that all authority ultimately derives from God, but we’re clearly capable of forming legitimate governments regardless of whether or not theism is true. There’s a lot of theory behind this, which I’ll only briefly touch upon. One could go back to Thomas Hobbes who argued for the authority of the sovereign, but did so on secular grounds rather than appeal to divine right. Building on Hobbes, social contract theorists came up with theories whereby political legitimacy comes not from the top down, but from the ground up. Legitimacy is bestowed on the government by the consent of autonomous, rational agents. I think a plausible case can be made that political legitimacy makes sense on purely secular grounds; one does not need to invoke the divine.
While this reasoning is relatively uncontroversial (excepting theocrats on the lunatic fringe), parallel reasoning is controversial in the domain of ethics. I’m not sure why this is the case, because the historical development of political philosophy and moral philosophy are similar. For example, Kant’s moral theory depends on the rationality of the autonomous agent rather than on God’s commands. Again, we have a secular account of objective moral values that does not invoke the divine. One could also look at Contractarianism and Utilitarianism for other modern secular accounts of how we ground morality. These seem to me to be just as plausible as the secular rationales for modern political theory. Why, then, is it taken for granted that political legitimacy doesn’t depend on theism and the divine right of kings, but it’s controversial whether or not objective moral values depend on theism and divine commands? Is it because modern moral theories are much less successful or much less plausible than modern political theories? I don’t see any prima facie reason to think so. Granted, none of these moral theories is perfect, but neither is divine command theory without its problems.
So I’m at a loss to explain this asymmetry. I do believe in objective moral values and political legitimacy. I just see no more reason to invoke God in the first instance than in the second. I reject divine command theory for the same reason I reject the divine right of kings: modern philosophy has plausibly shown that we can ground both objective morality and political legitimacy in secular terms.