Evolutionary explanation of morality self-refuting?

[Tea Earl Grey Hot]

You seem to assume that our faculties can know truth though. I'm asking how can we know that we can know what's true. For instance, maybe 'x' can really equal 'non-x' in reality but because of evolutionary processes, we can't comprehend that truth because it wasn't beneficial to our survival. Theists would say that because God is good and that God is truth, he'd ensure mankind would have the ability to know truth. I'm not seeing any such guarantee from a naturalistic point of view.

Firstly, the same argument that works against evolution, works against the theistic perspective as well. Suppose god is actually evil and he is the god of lies, then he would not give us the capacity to know the truth. In which case, we would actually think that X is non-X and that god is good and god is the truth.

You see how that works? Whether or not we actually have the capacity to know the truth cannot be determined by where that capacity came from. The only way to determine it is by finding out if that capacity actually works.

Now, how do we determine if we actually have that capacity or not? You do it by measuring your knowledge against reality and seeing if measures up. To start measuring, you first need a starting point.

Let's start by asking how do we determine truth? Forget for a moment whether we actually have the capacity to know the truth and ask how any entity having this capacity would determine what is true. It would check the statement made against what is real. Suppose the statement is "an apple is red", then the entity would check whether a real, physical apple is actually red or not.

Now, let's go a step further and look at the example you provided. "Can X equal non-X"? Suppose, in reality, X can equal non-X. If this is possible in reality, then something can and cannot be itself at the same time. A statement can be true and false at the same time. This would mean that there can be no such statement such as truth. Then it wouldn't matter if you have the capacity to know the truth or not, because there wouldn't be such a thing as "truth" to begin with. Therefore, we can establish X is not non-X as a basic fact of reality that doesn't depend on whether we know it. Incidentally, this is the Law of Identity, the basic premise of all logic.

So, we've determined that for there to be such a thing as truth, the X can only be equal to X and since we have used our reasoning faculties to determine this, we can say that they work pretty-fucking-well. We have established two lines of reasoning here:
1. If there is such a thing as truth, then we have the capacity to know it. (as demonstrated here).
2. If there is no such thing as truth, then there is such a thing as truth (basically a self-refuting and meaningless statement).

Does this clear up why we safely say that our rational faculties actually determine the truth irrespective of where they came from? If this is too complex, there is a simpler argument, though I don't think it'd be as convincing. I'm presenting it anyway.

Can you actually know the truth?

1. There are only two possible options. Either you can know the truth or you cannot know the truth.

2. If you cannot know the truth, then all statements of knowledge you make are false.

3. This includes the statement of knowledge that "You cannot know the truth".

4. Therefore, that position is essentially self-refuting and the only option you are left with is "you can know the truth".

I think I understand now. This at least helps put atheism and theism on equal footing in terms of epistemology in my mind. Some theists might try to use the transcendental argument though but I've seen some good refutations of that.

Back to morality. Craig's comment was a response to an atheist's objection to a premise of the moral argument for the existence of God. Here's the argument (He assumes of course that morales aren't subjective and says that those who think so have an "impairment"):

1. If God does not exist, objective moral values do not exist.
2. Objective moral values and duties do exist.
3. Therefore, God exists.

The hypothetical atheist's response that sociobiological account invalidates moral experience was to premise 2.

Instead of summarizing Craig's entire response, you can read here: Click me

He says that the sociobiological account doesn't undermine the truth of moral beliefs. This answer seems to contradict his notion that the sociobiological account undermines the truth of our ability to know truth, correct?