For me, I don't think it's meaningful to think of two notes in a vacuum as anything. The logical part of me wants to think about it with math like you're sugges

For me, I don't think it's meaningful to think of two notes in a vacuum as anything. The logical part of me wants to think about it with math like you're suggesting, but 2 notes lack any context to give them meaning. Add another two to the chord or add other notes around it temporally, and now they don't sound bad at all. The idea of consonance and dissonance only makes sense to me within the framework of tension and release.