The Year-2000 column by the late, lamented Sam Francis that VDARE.com recently posted contains this excellent summary statement about the mentality of the Left:
It seems to be impossible for the left to acknowledge that those who disagree with it from the right do so because they are rationally convinced of the truth of what they believe and the moral necessity of acting on it. To the mentality of the left, there's always an ulterior, and discreditable, reason why anyone disagrees with it.
And it reminds me of an even pithier thought along similar lines by legendary political scientist Hannah Arendt, as quoted indirectly by historian Otis Graham in his superb book, Immigration Reform and America's Unchosen Future. On page 82, Graham recounts adjusting to the fact that "Racist!" had, by the mid-1980s, become an all-purpose smear, employed by the Left to quell rational discussion:
It took awhile to see this for what it was – a brutally effective, at first, attempt to intimidate and silence the opposition, counting upon deep reservoirs of white guilt. I recall the ripple of shock that went through a gathering of FAIR's Advisory Board when I told them, in a talk on what was meant by the new term "political correctness," that if they hadn't been called a racist that month, they must not have been doing their job as educators and citizen activists. "Rejoice in that name calling," someone else urged our group. If they call you a racist it means they are badly losing the argument and are forced to reach deed into the slimy depths of their bag of arguments in a desperate last ditch effort to push you out of the debate. As Hannah Arendt wrote, a favorite tactic of the dictators of the 1930s was to turn every statement of fact into a question of motive.
[Italics added by PN.]
I've subsequently seen the Arendt quote, with slight variations, in several places, but I haven't been able to find the original source.