Evolution of morality

[theVOID]

The applicable definition of "moral", I believe, is: Doing what is right, just or fair. (I'm open to other interpretations.)

None of those three principles (right, just and fair) are objective.

Depending on how you define those terms they can be.

If I were to disagree with you about the rightness of a certain action, there would be no way to judge which one of us is correct without referring to either of our moral frameworks.

Agreed, then it becomes a case of which moral framework is better.

The very idea of a fundamental principle of morality is logically circular.
You want to build a moral code based on a fundamental principle, but that fundamental principle has to be defined by your moral code.

Yep That's the entire problem with Categorical imperatives.

Any solid moral theory has to start from a theory of value, not some assumption of categorical right and wrong.