WASHINGTON -- The craziest thing about the Republican presidential contest isn't that Donald Trump is in the lead. It's that Dr. Ben Carson -- who truly seems to have lost his mind -- is in second place and gaining fast.

Trump may be a blowhard, but Carson has proved himself to be a crackpot of the first order. Of all the GOP contenders, he's the scariest.

I say this as a longtime admirer of Carson for his stellar medical career. As the head of pediatric neurosurgery at Johns Hopkins, Carson not only saved lives in the operating room but also inspired countless young people to overcome rough beginnings and reach for the stars.

That sounds like a cliche, but I've seen the effect Carson has on a room full of low-income African-American students when he tells the story of how he escaped a childhood of poverty in Detroit to graduate from Yale, study medicine at the University of Michigan and become one of the most acclaimed surgeons of our time. Carson's message -- if I can do it, so can you -- has a powerful impact on young people. I wish he were still delivering it.

Instead, alas, he is running for president. And despite spouting more utter nonsense than the law should allow, Carson has the support of 18 percent of GOP voters, according to the Real Clear Politics poll average -- five points behind Trump and miles ahead of the rest of the field.

Carson speaks softly, slowly, thoughtfully. Much of what he says, however, is dangerously wrong.

His most recent burst of blather was over gun control in the wake of the Oregon massacre. As recently as Sunday, on "Face the Nation," Carson was defending his assertion that the Holocaust would have been "greatly diminished" if Jews had been able to keep firearms in their homes. Gun control laws enacted by the Nazi regime, he contends, were a prelude to genocide.

To say that experts disagree is an understatement. As Jonathan Greenblatt, national director of the Anti-Defamation League, wrote in The Huffington Post: "It is mind-bending to suggest that personal firearms in the hands of the small number of Germany's Jews (about 214,000 remaining in Germany in 1938) could have stopped the totalitarian onslaught of Nazi Germany when the armies of Poland, France, Belgium and numerous other countries were overwhelmed by the Third Reich."

Greenblatt added that it is "wholly inappropriate and offensive" to "manipulate the history of the Holocaust and use it to score political points."

It is equally beyond the pale, in my view, for Carson to have written on Facebook that while he saw the horror of gun violence as a youth in Detroit and as a doctor in emergency rooms, "I never saw a body with bullet holes that was more devastating than taking the right to arm ourselves away." Or to have implicitly criticized the victims in Oregon by saying that "I would not just stand there and let him shoot me," stating that people who find themselves in such circumstances should rush the gunman.

Carson's story of a personal encounter with firearms is just weird. "I have had a gun held on me when I was in a Popeyes organization," he told an interviewer, referring to the fried chicken chain. "Guy comes in, put the gun in my ribs. I just said, 'I believe that you want the guy behind the counter.'"

It is unclear what happened next. And it is unclear to me, frankly, that this really happened, though Carson swears it did. For one thing, Carson is a vegetarian; his campaign says he went to Popeyes for French fries. I wonder if he also goes to KFC to get coleslaw.

Disturbingly, Carson is a fan of dark conspiracies. Witness his claim that Palestinian leader Mahmoud Abbas, Iranian Supreme Leader Ali Khamenei and Russian President Vladimir Putin got to know each other in Moscow in 1968. All of them, he claims, were at Patrice Lumumba University at the time.

PolitiFact looked into the matter and found one meager shred of evidence that Abbas might have attended the university, though no indication of when; zero evidence that Khamenei ever studied in Moscow; and the inconvenient fact that Putin was 16 at the time. PolitiFact's verdict: "Pants on Fire!"

Carson has compared the Affordable Care Act to slavery. He has called President Obama a psychopath. He disbelieves established science on evolution and climate change.

I could go on and on, but I struggle to keep up with the good doctor's mouth.

(c) 2015, Washington Post Writers Group