Evolutionary explanation of morality self-refuting?

[FallentoReason]

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.

Agreed, but again, the only way I know how to do that is by using the thing I'm trying to prove is reliable. Circular reasoning.

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.

Well, what is reality? I forgot the person's name, but someone throughout history started questioning his very own existence. He argued that reality was playing tricks on him e.g. a cup looks circular from the top but looks rectangular from the side, and flat in both instances which it is not. Let's see if you've defined reality.

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.

You're taking so much for granted here, as if it's obvious. What is the colour red? For all you know you've been taught that an apple is red but your red registers as green in my brain. We have no way of knowing how someone percieves something. Only they know what 'reality' looks to them but there's no way of measuring that against a 'universal' standard so that we can determine it is in fact reality. If you think there is such a thing, then please describe 'red' to me.

I'm at university at the moment an I have to get going. I'll discuss the second half when I'm free.