We could simply map front/back = law/chaos and closed/open = good/evil… but that’s booooring.

Instead, let’s say:

• Cardinal vowels are lawful, glides are chaotic. Everything else is neutral.
• Good vowels are only defined by height, backness, and roundness. Give them an additional contrast and they become neutral, two and they’re evil, three and they’re the sounds uttered by Satan when you just reach Hell.

So for example the schwa strictu sensu is true neutral - it isn’t just a central vowel, it’s also reduced (shorter). Something like [ɜ̃͜ʊ̃] is chaotic evil. But most languages have a backbone of lawful good vowels.