It sounds like you're proposing something akin to cultural relativism. The foundations of American democracy are definitively not in cultural relativism, but in

It sounds like you're proposing something akin to cultural relativism. The foundations of American democracy are definitively not in cultural relativism, but in cultural absolutism: "All mean are created equal, etc etc". Now, we've often failed to live up to those words in the past, but it's an (ideally) constantly-improving process. Regardless, it's much, much more desirable than some anarchical cultural relativism where everyone does what they damn well please.