Unfortunately, I did not have time to read all of Mere Christianity like I did with The Screwtape Letters—for one, I didn’t have a copy of Mere Christianity handy, and second even the few chapters I read for class were much weightier than Screwtape. This is a book I should set aside a week or two’s worth of evenings to walk through and ponder. If you hurry through his arguments, you’ll miss a lot of their depth and beauty.
In Mere Christianity, Lewis lays out a thorough and methodical argument for the rationality of Christian belief, beginning, not with the existence of God or the divinity of Christ, but with the idea of a universal “moral law” under which all human beings live and according to which we judge our behavior and that of others. This moral law is a “natural law” in that all human beings have an inborn sense of it; however, it is different from other natural laws like the law of gravity or the law of heredity in that human beings can choose whether to follow it or not. A snowflake has no choice about following the law of gravity—it falls whether it wants to or not. A person, however, may steal even though he or she know that stealing is wrong.
A problem arises, however. First, looking at the great diversity of human cultures that have existed throughout history, and seeing that every culture has different values, practices, and beliefs, how can we possibly claim that there is a universal “moral law”? Morality, since it differs based on culture, must be a product of culture, a human creation. If morality is a human creation, however, it can be flawed. It is not absolute. Thus, it can be changed or abandoned entirely without any real consequence—there is nothing of substance backing it up.
Lewis argues that even those who claim there is no universal standard of right and wrong really believe that there is, and that this belief is evident in their actions. Though they may use the apparent absence of a fixed morality to excuse their own behavior, they are quick to point out when someone has treated them unfairly. And in order for something to be ‘fair’ or ‘unfair’, doesn’t there have to be a mutually agreed on standard of behavior between the people involved? Thus, the moral law is real and binding, no matter how inconvenient it may be; and all human beings, though they are aware of the moral law, fail to keep it perfectly.
Lewis then refutes two objections—first, that the moral law is just another of humanity’s instincts, and second that it is merely a “social convention”, as evidenced by the fact that moral values are passed down to us as children by our parents and teachers. An instinct, Lewis says, is “a strong want or desire to act in a certain way”—for example, to find food, or mate, or even to help someone else in need. However, there is a difference between wanting to help someone and knowing, deep down inside, that you should help them, even at great risk to yourself. This sense of what a person should do is the moral law, and it guides us when deciding which of two conflicting instincts (such as our desire to help someone and our desire for self-preservation) to follow. Lewis then points out that , while it is true that we learn about the moral law from others, that does not necessarily make the moral law a human creation. Many of the things we learn about have not been invented by human beings, but merely discovered—such as mathematics, biology, and the laws of physics. The moral law is one of these things, and we can tell that it is so because it is the standard by which we judge the moralities of other times and places to be “better” or “worse” than our own.
And finally, Lewis moves on to what lies “behind” the moral law—to the question, “Why is there something and not nothing?” Broadly, one can take a materialist view which states that the universe as we know it exists by chance, or one can take a religious view, which states that the universe came about under the will and direction of Something, or Someone. This is, in my opinion, where Lewis’s argument ceases to be completely water-tight. He is not seeking to prove the existence of God, like Aquinas or Anselm, but to show how rational such a view is, and how likely it seems compared with the materialist view. The argument he offers in favor of it is a good one—that, if there were a guiding force behind the universe, it would be expected to reveal itself to us in something like the moral law we all experience.
It’s a bit harder to tie Mere Christianity to my own life than Screwtape or even many of his essays. In conclusion, I’d just like to emphasize how much I enjoyed Lewis’s style of argument. His points were easy to understand, and he moves slowly enough that I had no trouble keeping up with him. As I said, his main aim seems to be not to prove that Christianity is true, but to persuade people that it is true—a far greater service and far more effective at convincing people to believe, I think, than a purely logical argument in favor of God’s existence. There is no philosophical or logical jargon here, and even an absence of Lewis’s normal poeticism. He is plain-spoken and down-to-earth. If I have time in the next couple of weeks, I would love to continue reading Mere Christianity.