So if I’m understanding your reasoning here, we can’t know anything (in the classic sense) so therefore we must look to consequences (which we also can’t know) as the only framework.
Pardon the poor grammar, I think my framework is as good as yours. ;-) And attempting to prove me wrong would be a waste of our time, since nothing is knowable in a meaningful sense.
While in theory, I understand what you are saying, nobody lives their life like that. In experience, right and wrong are in fine shades of grey until it’s something we care about. Then suddenly everything is black and white.
And while my response is probably poorly articulated and opaque, my point is that if two people do not agree about aims and what is good, they will certainly find no agreement regarding consequences. The history of philosophy would, I believe, support that conclusion.
Therefore I think it is more profitable to argue about our concept of good, even if it proves impossible to convince someone, because we reach the root of our disagreement more quickly.