Everyone has heard people quarrelling. Sometimes it sounds funny and sometimes it sounds merely unpleasant; but however it sounds, I believe we can learn something very important from listening to the kind of things they say. They say things like this: ‘How’d you like it if anyone did the same to you?’–‘That’s my seat, I was there first’–‘Leave him alone, he isn’t doing you any harm’–‘Why should you shove in first?’–‘Give me a bit of your orange, I gave you a bit of mine’–‘Come on you promised.’ People say things like that every day, educated people as well as uneducated, and children as well as grown ups.
Now what interests me about all thse remarks is that the man who makes them is not merely saying that the other man’s behaviour does not happen to please him. He is appealing to some kind of standard of behaviour which he expects the other man to know about. And the other man very seldom replies: ‘To hell with your standard.’ Nearly always he tries to make out that what he has been doing does not really go against that standard, or that if it does there is some special excuse….
This law [or standard] was called the Law of Nature because people thought that every one knew it by nature and did not need to be taught it. They did not mean, of course, that you might not find an odd individual here and there who did not know it, just as you find a few people who are colour-blind or have no ear for a tune. But taking the race as a whole, they thought that the human idea of decent behavior was obvious to every one. And I believe they were right. If they were not, then all the things we said about the war were nonsense. What was the sense in saying the enemy were in the wrong unless Right is a real thing which the Nazis at bottom knew as well as we did and ought to have practised? If they had had no notion of what we mean by right, then, though we might still have had to fight them, we could no more have blamed them for that than for the colour of their hair…
Clive S. Lewis, Mere Christianity, p. 3, 5