My opinion is that Lewis says there is right and wrong, gives examples, then says there are absolute moral values. He does define right and wrong before making his case that absolute right and wrong exist.
When this can be established he may then ask, "Where do absolute moral values come from?". (but he is careful to not affirm the consequent) Then he presents his argument.
Morality is a concept that evolved because it helps us form our societies. You don't need a god to have morals. I invite you to check an encyclopedia article on ethics. As I am not a philosopher or ethicist I found a professionally written article on the subject in Britannica. There are ethicists who do exclusively work in non-god centered ethical systems, probably the majority of them, which is counter to the propaganda of some evangelical writers. The fact that such ethicists do professional work without god proves...C. S. Lewis' opinion as a Professor of English is beside the point...that god isn't a requirement to morality.
Contrawise, it is my understanding that being ethical because of belief in god does not neccessarily mean you are dependent on god for your morality.
(I shall use the term God instead of Necessary Being) Although, it is my understanding that just because one may practice ethics without God does not imply that they are not dependent on God. That is, it is possible that an atheist could be not living in accord with his world view. You also said that ethics evolved for the better of society. Lewis also commented on this. (pp. 24-please, do read it again)
This is where Lewis says morals are not a social convention because it is like math, a real rule, not just a "convention". To show that ethics are math-like he says you can compare the ethics of different societies...but the moment you do (he writes) you compare them to a real standard. The real standard is god's ethics. NO, when you compare things, you compare them to each other NOT to a standard. In my review I use the comparison of pencils as an example of comparrisons to real concrete things not just to ideas. Lewis' statement that you are "comparing them", ethical systems, "both to some Real Morality" is just not convincing. You can compare things to an imaginary standard but it isn't neccessary and if you do imagine a standard, even an ethical standard, you are using your brain to imagine it, to create it on the fly.
This is very good thinking. Although, your analogy is not complete. And here is why: When you compare two properties (or a "thing" that has properties), in general you only compare the common characteristics and the lack of characteristics. For instance, when juxtaposing two pencils one might be yellow, long, and hard, whereas another might be blue, short and hard. You can look at them together and say, "Well, the blue one has the characteristic of blueness and the other does not," and merely compare the differences and similarities. But this does not hold true for ethics and moral values. When comparing two moralities, you can say, "Yes, this moral creed follows that you should not do such-and-such" and "this other morality allows you to do such-and-such," but when we ask which one is better then is when we compare to another standard. Besides, how can anyone even conceive of what true Justice is anyway- it has never been observed. This was one of Plato's arguments in the Phaedo which still is hard for distinguished atheist like Anthony Flew to answer today. It seems as though we have an idea of what justice should be, yet we did not receive this idea via our senses. How then did it come about? Theism provides us with the best answer for such abstract entities. You may show the likes and differences, but one is in no stance to say which is better or which is worse. Thus, if someone were to kill your child [sorry to be so crude, but I need it to demonstrate a concept] you would have no right to be angry at the murderer on the basis of moral relativism. If you did then you would not be living to the full extent of your worldview. It would not make sense for you to be angry. You also mentioned that one is not selfish because he needs acceptance by others, which appeals to the hierarchy of needs. Thus, if the murderer could get away with the crime then it would be perfectly fine to such a heinous act. We all can agree that what Hitler did was wrong, but if he could do it and get away with the consequences, then according to the atheist (or moral relativist) what he did was perfectly fine. This is because without God, all things are permitted. But it is hard for any human to live by such a creed.Besides, if it were just a convention, evolved via nature, then there is another problem with this too. I quote Lewis (pp. 29) If we ask: "Why ought I to be unselfish?" and you reply "Because it is good for society, "we may then ask, "Why should I care what's good for society except when it happens to pay me personally?" and then you will have to say, "Because you ought to be unselfish" -which, simply brings us back to where we started. . .
But that isn't the answer. The answer is because if you behave in a selfish way your interactions with other people will decrease because other people will avoid interacting with you to avoid your selfishness. It is best for you in the long run to behave unselfishly. I mention Maslov's Needs Hierarchy in my review. One of my needs, after I'm fed and clothed, is self-esteem and I can acheive some self-esteem by unselfish behavior. Unselfishness is a requirement for social beings to have a society, which is not where we started because it does pay individuals, and their genes, to behave unselfishly despite Lewis' pontification.
In the same way, if a man asks what is the point of behaving decently, it is no good replying, "in order to benefit society," for trying to benefit society, in other words being unselfish (for "society" after all only means "other people"), this one of the thing decent behaviour consists in; all you are really saying is that decent behaviour is decent behaviour. . .
I believe it is key to understand this. For a different treatment of the subject I have come across a good website with many articles concerning philosophy of religion, science and theology, www.leaderu.com. For the exact article on this subject see : http://www.leaderu.com/offices/billcraig/docs/meta-eth.html
I'll have to read more of this one later. My cursory viewing leads me to believe his argument rests on the need for souls to exist to face eternal punishment or eternal blessedness. He does say atheists can behave morally and ethical systems do not require god. It looks like his whole reason rests on "eternity" whatever that is.
Dr. Craig's argument rests on the idea that morality must neccessarily have an eternal referent. Do all ideas need eternal referents? Love, chaos, hate, apathy, for example? If the answer is yes then, instead of proving god's existence, you are saying a spirit world of forms exists which, I think, is the same as saying a world made by god exists so your preceeding the proof that god exists by saying god exists. And that is no argument either for god's existence or for forms. If the answer is no, then why is the topic of sthics and morals different in that it REQUIRES an eternal referent? This forms stuff hasn't even been taken seriously by professional philosophers for a couple hundred years and skepticism on it goes back even further.If you click on 'apologetics' you will find may thought provoking articles. Or if you wanted to read a book on the issue, Dr. William Lane Craig's book Reasonable Faith touches on this issue in chapter two. Or pick up a copy of Does God Exist? This is a debate between Dr. J.P. Moreland (theist) and Dr. Kai Nielson (atheist). The majority of the book is the debate, but in one part there is a debate between them concerning the nature and dependence/independence of ethics. I appreciate you reading what I have written and I look forward to future conversation.
I still think, as I wrote before, that Dr. Craig confuses "sin", a wrong against god, with "immoral", a wrong against society or one of its members from the standpoint of that society or individual. And while wrong is wrong, the acknowledgement of wrong does not also acknowledge the existence of sin.
Dr. Craig's writes that atheists can be moral, at one point he says a system of ethics can be worked out if an atheists grants human beings objective value. The rest of his paper seems to ignore that statement, or perhaps I'm missing the reason atheists cannot grant value to human life. A system of thought that holds natural material life as the only life a person has, the materialist non-spirit view most atheists have, should value life more than a system where spirits cavort eternally with angels. Dr. Craig's characterization of atheists, admittedly borrowed from another, as having a "cynical sense of futility" is nonsense, or so I'd argue based on my own experience as an atheist.
Dr. Craig simply states that it is a fact that we all "apprehend objective values, and we all know it" as if it is a proof of anything. I see no support for this statement. Rather I see that people who commit wrongs against individuals are assured in their own minds that they are doing right.
Lastly, Dr. Craig condemns naturalism because it removes the persoanl agent, the soul, that the justice of god is carried out against. Naturalism moves the personal agent from the soul to the workings of the brain. The brain is the engine of personality and of thought and no supernatural entity is required to make a brain work, at least that is the direction neuroscience is certainly taking. I refer you to "Neurophilosophy" or "Astonishing Hypothesis" for a naturalistic explanation of brains and the success of naturalism. Plato and Aristotle, who came up with this idea of eternal forms, came from a society that valued hanging out and thinking about things above doing things. Technicians and artisans were slaves, even educators were slaves. That was then. Now we explore things by physically examining them. Eternal "forms" do not stand the test of hard-headed reality.