THE PRESIDENTIAL candidacy of Libertarian Gary Johnson raises many questions. None of the answers are flattering to him.

Did Mr. Johnson learn much from his two terms as governor of New Mexico, or from his previous national presidential campaign? Does he prepare for major interviews — let alone for being president? First, Mr. Johnson flubbed a question on the slaughter in Aleppo, Syria — “What is Aleppo?” he asked. An isolated moment of confusion might be understandable. But Mr. Johnson had what he called another “Aleppo moment” Wednesday. Asked to name his favorite world leader, Mr. Johnson flailed for nearly a minute. Though interviewer Chris Matthews tried to help him, he failed to produce a single name. The next day, Mr. Johnson attempted to brush off the incident with what his campaign called a joke, tweeting, “It’s been almost 24 hours . . . and I still can’t come up with a foreign leader I look up to.” No matter how you interpret this, it is not good. As New York Post columnist John Podhoretz asked, could he not come up with lifelong Burmese freedom fighter Aung San Suu Kyi? Did the name Angela Merkel ring no bells?

Which raises questions for Mr. Johnson’s supporters: Do ideological libertarians really want this man to represent their movement? Does his loopy campaign bring credibility to their political philosophy?

To those who support him out of disgust with “the system” — or, perhaps, because of his stand favoring marijuana legalization — do you know what else he stands for? He opposes strong federal action to address climate change. He supports the Supreme Court’s Citizens United ruling, which stands at the core of Sen. Bernie Sanders’s (I-Vt.) criticism of “the system.” Mr. Johnson opposes the national minimum wage. He opposes federal aid for college students. He opposes government involvement ensuring universal health-care coverage. He opposes rudimentary gun regulations. His views do not, as some might suppose, represent a sensible, reality-based combination of fiscal reason and social tolerance; he favors less government even where government is badly needed.

Here’s another question: Does Mr. Johnson’s running mate, former Massachusetts governor William Weld, who is much sharper, really want to help Donald Trump win — and be remembered as the Ralph Nader of 2016? Mr. Johnson takes more support from Hillary Clinton in three- and four-way polls than he does from Mr. Trump. He could swing Colorado or New Hampshire into the Trump column. How could Mr. Weld, who acknowledged the danger Mr. Trump poses in an interview with us in July, live with his complicity in electing the Republican nominee?

How, indeed, could anyone? This is not a case of having to choose head over heart, and vote strategically. Mr. Johnson is good-natured but wholly unprepared — and unwilling or unable to learn. In this case, head and heart should come to the same conclusion.