In a healthy political climate, people from different political parties or different sides of the debate will argue about how best to respond to the facts. Liberals and conservatives will disagree about that response. Such disagreement may be partisan, heated, angry, vicious and unyielding. It may get personal and uncivil, with red-faced partisans screaming at one another, employing profanity, hyperbole and insult. It may get really nasty.
And all of that is OK.
Such nastiness may be a sub-optimal expression of healthy democracy, but it’s still an expression of healthy democracy. Now matter how heated the argument over how best to respond to the facts, that argument is evidence of a people still capable of self-government.
But when the argument shifts from how to respond to the facts to become an argument over the existence of the facts themselves, then self-government is no longer possible.