Why believe in evolution?

In the talk.origins newsgroup on May 25, 1992, Daniel Levy propounded the following question:

If naturalistic evolution is what has produced us people, then… WHY SHOULD ANYONE BELIEVE IN IT? Note carefully what I said: Why SHOULD anyone believe in it? I know there are a hundred explanations as to why anyone MIGHT HAPPEN TO believe in it, or MIGHT FIND THEMSELVES WANTING to believe in it, but that’s not what I said. I said: Why SHOULD anyone believe in it?

This article is an adaptation and expansion of an article I wrote in commentary on the resulting thread.

There were sundry indignant replies to Daniel’s question, replies that amounted to, IMHO, “because it’s true” and “what a stupid question”, neither response being responsive. In my view what Daniel wass getting at it is: Should is a moral normative term; if evolution is true then what basis is there for moral norms. Now there are several questions that I see:

a) Are there moral values?
b) Is a preference for truth a moral value?
c) What is the origin of moral values?
d) Are moral values absolute?

Judging from the postings of sundry creationists, the creationist position is (a) yes, (b) no, (c) God, (d) yes.

My personal answers to these questions are:
a) Yes.
b) Yes.
c) Twofold — species specific and intrinsic to the Universe
d) No in the sense of Christianity, Yes in the workings of Universe

It seems to me evident that a moral sense is part of our equipment, that it is a product of our species’ evolution. We have a built-in sense of right and wrong, of should and should-not, because having this sense is advantageous to a social species.

Moral values have multiple origins — some are intrinsic and some are learned. The intrinsic ones are those which are selected for because they reflect the way things work. Thus, a preference for truth is a moral value, because self-deception is generally disadvantageous. Mind you, this is an explanation for origin, not a justification.

In short, in my view, we are moral creatures because we evolved into being moral creatures. Knowing (or believing) that our morality was evolved rather than God given does not remove its impact; we violate our moral nature at our peril — in the short run because we act against our nature, and in the long run because it is to our disadvantage.

Because we are intelligent and can reason about our values, we can change them. It is this uncertainty, this sense that “what is right” is not necessarily right, that morality can be capriciously changed, that motivates questions such as Levy’s.

However morality and our moral reasoning cannot be capriciously changed. We cannot escape having a sense of right and wrong. We can reason about moral values and even change and redefine them, but all reasoning and change must take place within the context of existing moral codes and ethical philosophy. Above all, morality is always constrained by the primitive senses of fairness and empathy, senses that infuse morality with the spirit and not just the letter.