The propounders of what are called the “ethics of evolution,”... adduce a number of more or less interesting facts and more or less sound arguments in favour of the origin of the moral sentiments, in the same way as other natural phenomena, by a process of evolution.Huxley's right, of course. If the inclination to be kind and tolerant has evolved in the human species then so has the inclination to be selfish, violent, and cruel. So if evolution is to serve as our "moral dictionary" what grounds do we have for privileging kindness over cruelty? Both are equally sanctioned by our evolutionary history, and thus we can't say that either is better or more right than the other.
I have little doubt, for my own part, that they are on the right track; but as the immoral sentiments have no less been evolved, there is, so far, as much natural sanction for the one as the other. The thief and the murderer follow nature just as much as the philanthropist.
Cosmic evolution may teach us how the good and the evil tendencies of man may have come about; but, in itself, it is incompetent to furnish any better reason why what we call good is preferable to what we call evil than we had before.
Huxley goes on to dispense with the notion that the evolutionary development of our ethical sensibility can provide us with some sort of guide to our behavior:
There is another fallacy which appears to me to pervade the so-called “ethics of evolution.” It is the notion that because, on the whole, animals and plants have advanced in perfection of organization by means of the struggle for existence and the consequent ‘survival of the fittest’; therefore men in society, men as ethical beings, must look to the same process to help them towards perfection.The problem is that, for naturalists, the processes of nature are the only thing they can look to for moral guidance. Having rejected the notion that there exists a transcendent, personal, moral authority, the naturalist, if he's to avoid nihilism, is left trying to derive ethics from what he sees in nature, which leads to what I regard as the most serious problem with any naturalistic ethics: There's simply no warrant for thinking that a blind, impersonal process like evolution or a blind, impersonal substance like matter, can impose a moral duty on conscious beings.
Moral obligations, if they exist, can only be imposed by conscious, intelligent, moral authorities. Evolution can no more impose such an obligation than can gravity. Thus, naturalists (atheists) are confronted with a stark choice: Either give up their atheism or embrace moral nihilism. Unwilling to do what is for them unthinkable and accept the first alternative, many of them are reluctantly embracing the second.
Consider these three passages from three twentieth century philosophers:
I had been laboring under an unexamined assumption, namely that there is such a thing as right and wrong. I now believe there isn’t…The long and short of it is that I became convinced that atheism implies amorality; and since I am an atheist, I must therefore embrace amorality….What these thinkers and dozens like them are saying is that the project of trying to find some solid, naturalistic foundation upon which to build an ethics is like trying to find a mermaid. The object of the search simply doesn't exist, nor could it.
I experienced a shocking epiphany that religious believers are correct; without God there is no morality. But they are incorrect, I still believe, about there being a God. Hence, I believe, there is no morality….
Even though words like “sinful” and “evil” come naturally to the tongue as, say, a description of child molesting, they do not describe any actual properties of anything. There are no literal sins in the world because there is no literal God…nothing is literally right or wrong because there is no Morality. Joel Marks, An Amoral Manifesto
The world, according to this new picture [i.e. the picture produced by a scientific outlook], is purposeless, senseless, meaningless. Nature is nothing but matter in motion. The motions of matter are governed, not by any purpose, but by blind forces and laws….[But] if the scheme of things is purposeless and meaningless, then the life of man is purposeless and meaningless too. Everything is futile, all effort is in the end worthless. A man may, of course, still pursue disconnected ends, money fame, art, science, and may gain pleasure from them. But his life is hollow at the center. Hence, the dissatisfied, disillusioned, restless spirit of modern man….
Along with the ruin of the religious vision there went the ruin of moral principles and indeed of all values….If our moral rules do not proceed from something outside us in the nature of the universe - whether we say it is God or simply the universe itself - then they must be our own inventions. Thus it came to be believed that moral rules must be merely an expression of our own likes and dislikes. But likes and dislikes are notoriously variable. What pleases one man, people, or culture, displeases another. Therefore, morals are wholly relative. W.T. Stace, The Atlantic Monthly, 1948
We have not been able to show that reason requires the moral point of view, or that all really rational persons, unhoodwinked by myth or ideology, need not be individual egoists or amoralists….Reason doesn't decide here….The picture I have painted is not a pleasant one. Reflection on it depresses me….Pure reason will not take you to morality. Kai Nielson (1984)