Lewis also dismisses the idea that the Law of Right and Wrong is a matter of how we are raised by our parents or are taught at school. He sees this Law that we know we should obey comes from a different place than home or school; it is not simply a social convention that humans came up with themselves.
Lewis admits we learn many things from our parents and teachers, including how to behave with other people. But this odd sense that we should do the right thing with other humans is bigger than "let's be nice to each other."
Lewis lived through World War II and so he occasionally uses examples from theis war period to clarify the Law of Human Nature (Law of Morality or Law of Right and Wrong). In this chapter, he shows that people living in Nazi Germany learned to believe an entirely different idea of what right behavior was than the people of other countries.
The people of Poland clearly felt they had been wronged by the Nazi leaders as did the Jews who lived in Germany or who lived in land captured by the Nazi military.
The children in Germany were taught successfully to tell on their parents if they suspected their own parents were not loyal to the Nazi leaders. As the Allied Forces finally crushed the Nazi regime, common German people admitted they knew all along they were doing the wrong and not the right thing.
And the Nazi leaders who tried to escape punishment knew all too well that they were wrong and not right. They tried to rationalize their actions, but knew full well that in pursuit of a perfect Arayan world, they had violated the rights of others.
So, yes, Lewis says, both good and bad behavior can be taught. The fact that we know which is good and which is bad demonstrates there is a Law of Right and Wrong that exists outside of social convention and education. It is very different than being taught to drive a car on the left side or the right side of the road.
The Moral Law that somehow none of us can escape does not come from us humans. It comes from an entirely different place and we all know it when we do something wrong because it did not measure up to this standard that all humans carry inside them.
As a postscript to this story of Nazi abuses, let me point you to an NPR story about agricultural and sexual slaves in America today. Again, these "slave owners" know they are doing wrong because they go to extremes to hide the wrong, very wrong, things they are doing.
They rationalize their behavior but cannot make the knowledge that they are breaking the Law of Human Nature go away ... a Law that comes from a higher place than any laws passed by our States or Nation.
A comment from this NPR story: "They're from - mostly, they're from Mexico and Central America, although, there are many slavery cases that involve U.S. citizens as well. It really runs the spectrum. The common character, though, is power and abuse. And the people who hold these people captives have some way of maintaining their power over them whether it's with debt bondage or ropes or drugs and alcohol. "
Some of these "slave owners" do get caught and are themselves jailed for inhuman behavior. They knowingly violated the most important law in the world -- the Law of Right and Wrong that every human on earth is aware of and knows he or she should follow this law. It is not taught to us; it is ingrained in us by some force outside of who we are just as surely as a stone will fall when dropped or a carbon atom will bond to other atoms to create new kinds of molecules, or that the universe is rapidly expanding.