[Thought experiment] If alignments are objective how do we know what they represent?

[Segev]

If I had to guess, that is probably an assertion, or definition, in IRL moral theory. Good = Moral, and possibly also = the correct/right "way to behave"/"thing to do".

Good = Moral is not how D&D or Palladium define any of the good Alignments. And the most recent version describes Alignment as moral & social attitudes that results in typical behavior.

If so, that means we know that some portion of the Alignment name labels, e.g. Good and Evil, isn't lining up with IRL Moral Theory.

I mean, there's a foundational problem, though: for any moral theory you care to outline, I can ask, "Why should I be moral?" There are ways to answer that, but all of them require things that have been rejected when I have proposed them. The trouble is that "should" and "ought" and the like require a purpose. They have a hidden assumption that there is a purpose for which you "should" do things. Without purpose, "should" is meaningless. When you say, "You should be moral," but define "moral" as "what you should do," you have a circular definition with no foundation.

So I ask this of anybody who cares to answer (though OldTrees1 is in particular invited to respond): "Why should I be moral?"