John C. Wright explains that the Left is evil, not stupid:
Leftists are people who have a conscience but act like sociopaths. If the Leftist were really a sociopath, he would not need excuses, justifications, and rationalizations to fill his yammering mouth and empty his wrathful brain.
Please note also that this behavior only surfaces on matters where the Leftist has turned Left and turned off his brain in a vain attempt to turn off his conscience, which he wrongly believes to be lodged in the brain. A Leftist can be a good coworker, even a good friend, if you stick to topics where the Leftist brain-parasite called guilt does not take root and bloom like ghastly fungi expanding from his hypothalamus and medulla oblongata to suck up all his gray matter and ooze sinuously out of eyes, nostrils, mouth, ears.
I have talked with social Leftists about economic issues, for example, without triggering their brain-fungi response. The Leftist will mouth the normal sounding American ideals about Life, Liberty and Pursuit of Happiness provided you do not crowd him too closely to ask him what those things mean, or why their heroes Che and Mao and crystal meth dealer Matthew Shepard slain by his gay lover and fellow drug dealer Aaron McKinney fit into the idea of the American Way, then and only then will the brain fungi erupt, and the human-shaped skull be cracked and flung aside, revealing the fleshy lobes and convolutions of the nonhuman being beneath.
Leftists are reasonable and decent people except in their particular areas of sensitivity, by which I mean, of course, where they are hiding their smothering guilt, and — this point bears emphasizing — not all of them are sensitive about the same thing, because not all of them sold the same section of their brains to the Fungi from Yuggoth for the same reason.
No one has sold all his brain, and no one is an entirely self consistent Leftist, so what triggers one Leftist into frothing inanity is not what triggers another. But the behavior once triggered is the same. That behavior is flight from reason.
As stated above, Leftism is what you get when you stop reasoning.
Their reasoning is marred and crippled because they mar and cripple reason so that reason will not operate properly. They want reason not to operate properly because reason shows them a truth that they cannot abide. They cannot abide the truth because the truth condemns them. Truth condemns them because they do evil.
We are all potential Leftists. We are all capable of rationalizing away our own particular sins. How good I am, because I am not a glutton, says the slender whore. How good I am, because I am not a slut, says the obese woman as she stuffs her face. How good I am, because I am not a murderer, says the homosexual. How good I am, because I am not a thief, says the killer.
It is only when attention is drawn to their own particular sin, to OUR own sin, that the human mind goes haywire, because it is hard to look at yourself in the mirror and say: “I am a sinner. I am corrupt. I am fallen short of the glory of God.”
And yet, whether we admit it or not, we have.
We sinners of the Right are no better than the sinners of the Left. We are only more sane because we do not run from our sins, we do not hide from them, and we know better than to try to justify them. But we commit them, all the same. Don’t pretend otherwise, for doing so is the first step on the path to becoming differently and incompletely sane.