When you said "ontological" I was reminded of a phrase I often encountered in leftist circles, the assertion some people are "ontologically evil". Precisely because they operate from a different set of axioms.

> therefore we have little to learn from arguing with each other

In a way I agree but at the same time I can't help but think exploring the axioms underlying moral foundations is important. Either to come to a shared set as a society or to construct a societal machanism that will allow people with a contradictory sense of morality to co-exist. To be honest, reaching a shared set of moral axioms seems to be a lost cause to me. But, perhaps the co-existance mechanism is still possible.