Minimum basis for rational discussionFor two people to have a rational discussion they have to be able to answer three questions in the affirmative: First, are there universal truths? Second, can we know them to a certain extent? And third, can we communicate them to others to a certain extent? The extent and manner of knowing and communicating can be a matter of discussion, but if "dialogue partners" don't agree on these three affirmations, they might as well get out the Scrabble board. All rational discourse ceases.
Of course, I have a friend who in principle agrees with me on these three (because he knows you can't be Catholic if you don't accept them), but who is so conscious of context and cultural overlays and all kinds of postmodern considerations that he winds up with a de facto rejection of the affirmations. This allows him, by the way, to reject the Church's teachings on sexuality.