Gary Johnson just proved he's not deep enough to be president

Libertarian presidential candidate Gary Johnson is finally getting attention - for not knowing what Aleppo is. (Aleppo is the city at the center of humanitarian crisis in the Syrian civil war.)

Obviously, Johnson was never going to be president, so the question of whether he knows enough about Syria to set America's foreign policy is mostly academic.

But his Aleppo answer is consistent with the sense I've developed about Johnson over the last four years, ever since I interviewed him for Bloomberg in the summer of 2012, during his last presidential campaign. That is: Johnson has a very superficial understanding of public policy, one that often leads him to bad ideas.

His knowledge gaps are somewhat offset by his humility: He's the sort of person who would admit something like not knowing what Aleppo is, and who would seek guidance with an open mind from wise people like his running mate, former Massachusetts Gov. Bill Weld.

But even after adjusting for humility, he simply isn't deep enough to be president.

Over the years, I've been most struck by Johnson's superficial and dangerous analyses of economic policy. Back in 2012, he told me our economic slowdown had persisted so long in part because home prices had not fallen far enough and there had not been enough foreclosures. He said America's monetary system was on the verge of collapse. He advocated an immediate, 43% reduction in Medicare spending.

He also said we would have recovered faster from the 2008 crash if large banks like Citigroup and Bank of America had been allowed to fail, a view he reiterated to my colleague Brett LoGiurato earlier this year.

These are bad ideas of the sort that you would form sitting around a table a libertarian college seminar, not by talking with real-world experts who deeply understand economic issues.

If he actually became president, I believe Johnson could probably be talked out of many of his bad ideas. But I'm not sure he'd be talked out of all of them. I would not be comfortable with him appointing members of the Federal Reserve Board, or making emergency decisions in an economic or foreign policy crisis.

It's probably better to admit you don't know things than to bluff your way through them, like Donald Trump does. But the best thing is to actually develop the knowledge you need to be a serious presidential candidate before running for president.

This is an editorial. The opinions and conclusions expressed above are those of the author.