A very popular argument with Christian apologists, including C.S. Lewis, is the argument from morality. According to Lewis, the only valid morality that can exist is an objective one all subjective conceptions of morality lead to ruin. Furthermore, an authentic objective morality must be grounded in a supernatural reality beyond our own world, thus he rejects all naturalistic conceptions of an objective morality as well. Does his argument succeed?
According to the Moral Argument, there is a universal human moral conscience which suggests basic human similarities. Everyone experiences an internal sense of moral obligation to do the right thing; Lewis asserts that the existence of a universal moral conscience, consistent across time and cultures, can only be explained by the existence of a god who created us. Furthermore, Lewis insists that earlier generations had a better grasp of Moral Law on account of their greater agreement on what constitutes moral and immoral behavior.
It is not true, however, that all humans have a moral conscience some are diagnosed without it and are labeled sociopaths or psychopaths. If we ignore them as an aberration, though, we still have vast differences in morality between different societies. C.S. Lewis claimed that different cultures had only slightly different moralities, but anthropologists and sociologists can only regard such a claim with derision. As a student of Greek and Roman history, Lewis himself surely knew that his claim was false.
What little agreement that can be identified is far too thin of a basis upon which he can found an argument such as this, but it can be explained in evolutionary terms. It can be argued, for example, that our moral conscience was evolutionarily selected for, especially in light of animal behavior which is suggestive of a rudimentary moral conscience. Chimpanzees exhibit what appears to be fear and shame when they do something that violates the rules of their group. Should we conclude that chimpanzees fear God? Or is it more likely that such feelings are natural in social animals?
Even if we grant all of Lewis false premises, though, they would not establish his conclusion that morality is objective. The uniformity of a belief does not prove it true or indicate that it has an external source. The fact that we desire to do things we know are wrong is given some weight by Lewis, but its not clear why because this, too, does not require that morality be objective.
Lewis doesnt seriously consider alternative theories of morality he only examines a couple, and even then only the weakest formulations available. He studiously avoids direct engagement with more powerful and substantial arguments either against objective morality or in favor of objective morality which is unrelated to the supernatural. There are certainly legitimate questions to be asked about such theories, but Lewis acts as if the theories didnt even exist.
Finally, Lewis argues that atheists contradict themselves when they act morally because they have no inherent basis for morality. Instead, he insists that they forget their ethical subjectivism and act like Christians that they borrow from the morality of Christianity without acknowledging it.
We hear this refrain from Christian apologists even today, but its a false argument. It simply will not do to claim that someone doesnt really believe what they say for no other reason than that it contradicts ones preconceived notions about what it is and is not plausible. Lewis refuses to engage or consider the possibility that atheists behavior is actually a sign that his own conceptions of morality are mistaken.
According to Lewis, A dogmatic belief in objective value is necessary to the very idea of a rule which is not tyranny or an obedience which is not slavery. This is polemic, not an argument, because Lewis does not establish that his sort of dogmatism is a prerequisite for a free society if, indeed, any dogmatism necessary.
C.S. Lewis argument that the existence of morality points to the existence of his god fails. First, it has not been shown that ethical statements can only be objective if you presume theism. There have been a number of efforts to create naturalistic theories of ethics which in no way rely upon gods. Second, it has not been shown that moral laws or ethical properties are absolute and objective. Maybe they are, but this cannot simply be assumed without argument.
Third, what if morals arent absolute and objective? This would not automatically mean we will or should descend into moral anarchy as a result. At best, we have perhaps a practical reason to believe in a god regardless of the actual truth value of theism. This doesnt rationally establish the existence of a god, which is Lewis goal.