Without such a shared premise as a bedrock, we cannot dispute matters rationally with one another, but only assert our particular subjective preferences and try to shout down those whose preferences conflict with our own. To deny this core principle is to deny what makes us human: it leads to a situation that is so ethically immature it does not even rise to the level of Paganism.
Which is why current debate involves more name-calling than attempts at persuasion through reason. Also the apparent belief in universities that the mere assertion of something determines its truth. No evidence or reasoning is needed in support and those who call for them are deemed simply evil.
