Quote Originally Posted by Grek View Post
I think people are kinda missing the point of the question here. Saint-Just isn't asking "Does Detect Good really detect whether or not a character adheres to the IRL Objective Morality?". I mean, obviously they're not, that's an absurd thing to ask. They're asking how people would figure out the criteria by which the various Detect [Alignment] spells decide how strongly to light stuff up when cast. And for that, you'd use some behavioral studies:
That is the nature of subthreads I suppose. People answer the main question to more or less detail, then a relevant tangent appears. In this case the subthread spun off of acknowledging that the philosophers of Sigil would still not agree on or know which Ethics System to use.

You provided great detail. Quertus mentioned an interesting possbility and I wonder how it impacts these studies:
What if the Detect spells are Detect Lawful Evil and Detect Chaotic Evil rather than Detect Good and Detect Evil? In this case they are not true opposites but still don't overlap.