Mere Christianity: Book 1, Chapter 2 Summary & Analysis

Lewis claims that he has now established a “foundation” for his argument: there is such a thing as a moral Law of Nature. In this chapter, he will strengthen this foundation by discussing moral law in more detail.

Some people might say that Moral Law is a kind of “herd instinct”—an intuition that has evolved over centuries, just like every other human instinct. To respond to this idea, Lewis imagines hearing a cry for help. If he were to hear such a cry, he’d feel three emotions—first, a desire to help; second, a desire to keep out of danger. But there would also be a third emotion—an intuition that the first emotion is “right” and the second emotion is “wrong.” So moral behavior may indeed be the product of instinct—but that doesn’t follow that morality itself is just instinct: that would be like saying that a sheet of music is the same thing as a piano key.

Another rebuttal to the theory that morality is instinct: if morality were a form of instinct, then most of the time, the instinct for self-preservation would trump it. When we hear someone in danger calling out for help, our instincts to save ourselves from the danger are probably stronger than our instincts to save others—yet often, we choose to risk our lives to offer help.

One final rebuttal: morality can’t just be a form of instinct, because there are no instincts that we consider to be moral one hundred percent of the time (e.g., some of the time, our instinct to love our mothers is moral; sometimes it isn’t). If morality were instinctive, then there probably would be some instinct that was always moral. By the same token, there is no such thing as a piano key that is right or wrong 100 percent of the time—sometimes a key can be right, and sometimes the same key can be wrong, according to the directions of the sheet of music. It’s worth emphasizing that no instinct is moral all the time. A lot of people build their entire lives around one specific instinct—to love one’s family, to protect one’s country, to have sex, etc. Such a life is deeply misguided, because people need morality to tell them when their instincts are good and when they’re not.

Another potential objection to the theory of moral law: moral law is just a social convention, something that we all learn from our schoolteachers. But just because we learn something from a schoolteacher doesn’t mean that it’s just a human convention—after all, two plus two equals four, whether we learn it in school or not. Strange though it might sound, moral law falls into the same category as a mathematical law: it’s a universal truth that transcends humanity.

Lewis now asks us to consider in more detail the idea that all moralities are fundamentally the same. Clearly, people over time have had some different ideas about what it means to be a good person. But the very fact that people do disagree on this matter suggests that there really is a correct answer to the question of what it means to be good. Consider the history of witch-burnings in England. For centuries, women were murdered for the supposed crime of witchcraft. One might point to witch-burnings as evidence for how greatly morality has changed over time—and therefore, how arbitrary it can be. But remember that the witch-burners of the past believed that witches were real. If modern-day people believed that certain human beings made pacts with the devil, they’d probably burn those people, just as their ancestors did. There is, in short, no real difference between a modern person’s morality and a witch-burner’s morality—the difference is that modern people have more knowledge.