Vor einiger Zeit habe ich die Argumentation für das universelle Moralgesetz aus dem ersten Teil von "Mere Christianity" im Rahmen einer Präsentation in englischer Sprache zusammengefasst. Der Text von Lewis ist aus einer Serie von Radioansprachen auf BBC während dem 2. Weltkrieg entstanden und hatte ein gewaltiges Echo ausgelöst.
In the first part of his defense of Christian faith, an Essay collection called „Mere Christianity“, C. S. Lewis introduces „Right And Wrong As A Clue To The Meaning Of The Universe” (Book 1). He recognizes a common human sense that he calls “the Law of Human Nature“.
That man intuitively distincts between Right and Wrong can be seen in his every-day life, for example when he is quarrelling:
Quarrelling means trying to show that the other man is in the wrong. And there would be no sense in trying to do that unless you and he had some sort of agreement as to what Right and Wrong are; just as there would be no sense in saying that a footballer had committed a foul unless there was some agreement about the rules of football. (21)
Even if man denies an absolute Right and Wrong, he refers on it when he calls something “unfair”. “Whenever you find a man who says he does not believe in a real Right and Wrong, you will find the same man going back on this a moment later.” (23) But man does not only have an idea on how to behave, he definitely fails to fulfill those rules:
These, then, are the two points I wanted to make. First, that human beings, over the earth, have this curious idea that they ought to behave in a certain way, and cannot really get rid of it. Secondly, that they do not in fact behave in that way. They know the Law of Nature; they break it. These two facts are the foundation of all clear thinking about ourselves and the universe we live in. (25)
Lewis further finds a narrower definition of the term “law” to distinguish between laws of nature and the Human Law of Nature. While the laws of nature cannot be changed, you can choose whether to obey or to disobey the Human Law of Nature:
The laws of nature, as applied to stones or trees, may only mean "what Nature, in fact, does." But if you turn to the Law of Human Nature, the Law of Decent Behaviour, it is a different matter. That law certainly does not mean "what human beings, in fact, do"; for as I said before, many of them do not obey this law at all, and none of them obey it completely. The law of gravity tells you what stones do if you drop them; but the Law of Human Nature tells you what human beings ought to do and do not. (32)
One may ask if that Law is only a temporal convention of society. Lewis replies: “If your moral ideas can be truer, and those of the Nazis less true, there must be something—some Real Morality—for them to be true about.” (29) Another argument for the existence of that ideal behavior is that it serves for our own convenience. That is not the case because the rules are often strictly opposite to man’s comfort or convenience. Lewis comes to the conclusion that there must be a rule of Right and Wrong that is not made by ourselves.
Men ought to be unselfish, ought to be fair. Not that men are unselfish, that they like being unselfish, but that they ought to be. The Moral Law, or Law of Human Nature, is not simply a fact about human behaviour in the same way as the Law of Gravitation is, or may be, simply a fact about how heavy objects behave. On the other hand, it is not a mere fancy, for we cannot get rid of the idea, and most of the things we say and think about men would be reduced to nonsense if we did. And it is not simply a statement about how we should like men to behave for our own convenience; for the behaviour we call bad or unfair is not exactly the same as the behaviour we find inconvenient, and may even be the opposite. Consequently, this Rule of Right and Wrong, or Law of Human Nature, or whatever you call it, must somehow or other be a real thing— a thing that is really there, not made up by ourselves. (34-35)
In the next section Lewis wonders “what lies behind the law”. There are two possibilities: It is mere accidental, or there is a personal power that installed that law.
The position of the question, then, is like this. We want to know whether the universe simply happens to be what it is for no reason or whether there is a power behind it that makes it what it is. Since that power, if it exists, would be not one of the observed facts but a reality which makes them, no mere observation of the facts can find it. (38)
If you decide there is somebody behind the law, you can ask how you can get information about him. As he is not the universe itself but the creator thereof, Lewis sees two ways to get evidence: Once the universe, secondly the Moral Law put into our minds.
We have two bits of evidence about the Somebody. One is the universe He has made. If we used that as our only clue, then I think we should have to conclude that He was a great artist (for the universe is a very beautiful place), but also that He is quite merciless and no friend to man (for the universe is a very dangerous and terrifying place). The other bit of evidence is that Moral Law which He has put into our minds. And this is a better bit of evidence than the other, because it is inside information. You find out more about God from the Moral Law than from the universe in general just as you find out more about a man by listening to his conversation than by looking at a house he has built. Now, from this second bit of evidence we conclude that the Being behind the universe is intensely interested in right conduct —in fair play, unselfishness, courage, good faith, honesty and truthfulness. In that sense we should agree with the account given by Christianity and some other religions, that God is "good." (42)