Does it make sense to vote for Gary Johnson, the Libertarian candidate for president? Sure, as long as you believe two things. First, you have to believe that it makes no difference at all whether Hillary Clinton or Donald Trump moves into the White House — because one of them will. Second, you have to believe that America will be better off in the long run if we eliminate environmental regulation, abolish the income tax, do away with public schools, and dismantle Social Security and Medicare — which is what the Libertarian platform calls for.

But do 29 percent of Americans between 18 and 34 believe these things? I doubt it. Yet that, according to a recent Quinnipiac poll, is the share of millennial voters who say that they would vote for Mr. Johnson if the election took place now. And the preponderance of young Americans who say they’ll back Mr. Johnson or Jill Stein, the Green Party nominee, appear to be citizens who would support Mrs. Clinton in a two-way race; including the minor party candidates cuts her margin among young voters from 21 points to just 5.

So I’d like to make a plea to young Americans: your vote matters, so please take it seriously.

Why are minor candidates seemingly drawing so much support this year? Very little of it, I suspect, reflects support for their policy positions. How many people have actually read the Libertarian platform? But if you’re thinking of voting Johnson, you really should. It’s a remarkable document.