Ethics presupposes deontology

I thought this sounded very succinct (subject, verb, predicate). Maybe "deontology" isn't the right word. Ethics presupposes a priori judgments in order to advance consequent moral contensions, and without those there is no basis for any ethical consideration. This is not to say that there aren't contingent ethical situations, but that those are based upon premises that rely on an a priori moral presupposition. This phrasing seems obvious and ostensibly unoriginal, but I thought it was a quick and easy way to state it.

4/16 update: I originally meant to put this remark in, but it's at least mildly interesting to look at this statement as a response to ethical relativism and do the math from there.