If I knew why I loved the beloved, this would not tell me if the beloved existed. I might love her due to me, but she still is. The origin of my feelings do not control her being. She might (after all) be an illusion, a siren or mermaid imagined at sea, or she might be more than the sum of my desires: an independent being not dependent on me in the slightest.
Suppose we had a full naturalistic account of how humans developed our present moral sense. We do not have such an account, but suppose we did.
What would that mean?
The brilliant team of scientists who discovered such a mechanism or history would deserve all the awards they would surely get. We would know that how we now think about some moral principle (“killing for fun is wrong”) is the product of natural causes. We believe because we came to be so due to evolution.
Does that count out God or the existence of moral facts?
By no means!
First, how I, a person, came to think a thing was true tells a good bit about me, but not nearly as much about the truth.
Take moral truths. Suppose I came to a moral truth through purely natural means. That would be possible if moral truths were objective (independent of my mind) or subjective. One reason evolution (to give one natural mechanism) could have produced moral reasoning would be that a being should conform to reality generally. Since moral truths are real, organisms that recognize those truths do better than those that do not. Perhaps, on the other hand, we came naturalistically to such truths because nothing is there, but for other reasons we (accidentally) came to the truths we have.
Who can be sure?
Notice that by itself knowing how we came to a moral truth says something about us and may be a bit about the cosmos, but much less definitive about the cosmos. For example, if we came to believe in moral truth because we came to believe in God, that would tell us about our beliefs (again), but not so much about what is real. We might as a result of this account of our moral truths look for the God who (may) have provoked them. We also could wonder, or even assume based on other philosophical ideas we held, that God did not exist.Imagine: we came to believe in morals based on our belief in God, but our belief in God is based on . . .
And yet really none of this would show whether moral truths exist.
They might or they might not.
There are two simple reasons to side with the existence of moral truths. First, we talk as if the moral truths exist. We say “that is good” . . . Not “I am feeling good about that.” Life keeps suggesting the moral truth is out there, not just inside. Second, if we think that other metaphysical beings exist (God, numbers, ideas), then the moral truths are not strange at all. Nature may have shown me the “good,” but the nature got her lesson in what to teach me from reality!
Finally, consider that all of us who talk about this topic keep smuggling moral language back into the discussion. Suppose millennia of Darwinism have made me think “X” is good. I shout “X is good” with all my heart. Sadly for me some snub nosed man comes to work and asks: “So? Is X good? Should we praise X?”
Saying “we just do” is not helpful. We could stop and condemn actions despite our feelings. The minute the “evolutionary account” is told us, then it has no control over us. I can say: “No” at least in my heart. Even if “evolution” forces me to do X, I can dissent from X.
I can hate what I must do.
And so why I think X is bad does very little to help tell me what X is.
Maybe my local Socrates is wrong to challenge me, because there is no “should” beyond my feelings. Perhaps, but I will not come to that conclusion based on words or feelings. Should I, after all, prefer my hard wired feelings (even if I cannot avoid having them) or my moral sense?
I love the beloved. That is a fact.
The Beloved may or may not exist. My love acknowledges what might be (God is not), but lives as if God did not exist to see. I have committed myself so hope to see!