Donald Trump has many serious flaws, including incorrigible dishonesty, rampant narcissism, contempt for women and a fashion sense that makes him think that hairstyle is flattering. But nothing compares to his most prominent, crippling and incurable defect: He's dimmer than a 5-watt bulb.
Secretary of State Rex Tillerson was reported to have called the president a "moron" - emphasizing that term with an emphatic adjective I can't repeat here. Forced to hold a news conference to praise the president's intelligence, Tillerson was too honest to deny what he had said.
The late William T. Kelley, who taught Trump at the University of Pennsylvania, said, "Donald Trump was the dumbest goddamn student I ever had." Tony Schwartz, the ghostwriter of "The Art of the Deal," says Trump had "a stunning level of superficial knowledge and plain ignorance."
Trump's feeble-mindedness is on daily view. When an Uzbek immigrant was arrested for allegedly driving a truck down a Manhattan bike path, killing eight people, the president responded in thunderously stupid ways. First, he tweeted that he had "just ordered Homeland Security to step up our already Extreme Vetting Program." If you can step it up, why didn't you do that before?
He fumed that the alleged killer wanted an Islamic State flag for his hospital room. Really? The guy reportedly killed eight people, and the flag is what steams you? Trump demanded the death penalty, opening the way for the suspect's lawyers to argue that the president has made it impossible for him to get a fair trial.
Trump has learned nothing from his past blunders. As a candidate, he said Sgt. Bowe Bergdahl was a traitor who should be executed. Asked about the case as president, he doubled down: "I think people have heard my comments in the past."
The military judge announced he would count Trump's statement as "mitigation evidence," which may be why he ended up giving Bergdahl no prison time. Not only was Trump's remark unnecessary and inappropriate; it was self-defeating.
He's just not bright enough to make connections between his conduct and its consequences. Trump's travel ban has lost repeatedly in court because he has made clear that he has an unconstitutional goal: shutting out Muslims because of their religion. If he had kept quiet, he might have gotten his way.
The evidence of his dimwittedness flows as continuously and voluminously as the Mississippi River. His tweets are studded with misspellings, random capitalizations and mystifying quotation marks.
He taps out tweets that flagrantly contradict what he tweeted when Barack Obama was president, making himself look ridiculous. When he holds forth on policy issues, it's excruciatingly apparent he has no idea what he's talking about.
Trump relies on a vocabulary the size of a fourth-graders. To combat opioid abuse among teens, he favors "telling them, 'No good, really bad for you in every way.'" Those paper towels he tossed to a crowd in Puerto Rico were "very good towels." He wanted to call the tax reform bill "the Cut Cut Cut Act."
He pretends to be a master negotiator, but he has failed to get the Republican Congress to repeal Obamacare, enact protections for immigrants brought here illegally as children, and fund his border wall.
Trump tries to conceal his intellectual deficiency by insisting how smart he is. "I went to an Ivy League college," he said last month. "I'm a very intelligent person." He has to make such affirmations because all the evidence indicates his cranium contains an airless void.
I don't mean to suggest his supporters are dumb. There are plenty of intelligent people who voted for him and plenty of stupid ones who didn't. But the smart Trump supporters don't hold his intellect in awe.
After Tillerson's "moron" comment was reported, Trump said, "I guess we'll have to compare IQ tests. And I can tell you who is going to win."
I'm sure plenty of readers are now saying I'm the stupid one, with a brain far inferior to Trump's. They may be right. So I put a challenge to him: We both take an IQ test, administered by an independent body, with the results to be made public.
This is a great chance to dazzle the world with his peerless mind. It's a chance for him to humiliate someone in the "fake news media" with his towering intellect.
But I'm betting Trump will never submit to any process that would document his actual intelligence for the public to see. He's dumb. But not that dumb.