"Bernie Sanders is a sitting United States senator who could easily finish second in the Democratic presidential primary," writes Ryan Cooper at the Week, making the very correct point that though Sanders's ideology is a bit marginal in US politics, it's by no means kooky. But then Cooper goes off the rails: "It is conceivable that he could even end up as Clinton's running mate."

I took a philosophy class once in which we had a spend a lot of time considering the proposition that we could conceive of a talking donkey whereas a square circle is a logical contradiction. And in that sense, yes, Sanders as Clinton's running mate is conceivable. But it would require both parties to concurrently lose their minds for it to materialize.

1) Bernie Sanders is an old, white veteran of DC

It's not that Hillary Clinton doesn't like old, white DC veterans. But that's exactly what she is. With a vice presidential selection, Clinton will be looking to do some mix of juicing minority turnout, gathering a sense of youth and energy, and conveying an in-touchness with outside-the-beltway Americans.

A guy who's been serving in Congress for a quarter of a century is a great VP choice for a youthful outsider type at the top of the ticket. That's why Bill Clinton tapped Al Gore and why Barack Obama tapped Joe Biden — the idea is to convey to the country and the party that you do in fact understand that mastering the ways of Washington is an important part of the job. But nobody worries about Clinton in this regard. She is, if anything, excessively qualified to be president in a country where trust in elites and institutions is low and constantly fading.

2) Bernie Sanders wouldn't want to do it

The modern vice presidency, despite its lack of formal powers, is actually a really great gig for the right kind of guy. If you are someone who is comfortable with your political party's basic consensus views, and also generally comfortable with the movers and shakers in the party, then you will love being a big-time cheerleader and implementer of that agenda. You just have to accept the reality that your role in actually deciding what the agenda is going to be is very limited, and your ability to dissent from decisions that have been made is essentially nonexistent.

None of that sounds like Sanders to me.

Indeed, Sanders spent his whole congressional career refusing to officially identify as a member of the Democratic Party! The whole reason his campaign has been exciting is that he likes to speak his mind and stake out bold positions. He doesn't want to be in a meeting about how the president doesn't want to stake out a position that will divide the Senate caucus so the vice president can't say such-and-such because it's not going to fly in Missouri and North Dakota and West Virginia, where incumbents blah blah blah blah.

3) The VP has to fundraise

Here's a Boston Globe story from March about Joe Biden coming to town for an "intimate fundraiser for the Democratic National Committee." It mentions that "the vice president headlined a fund-raiser for the DNC in October" and also that "he was back in town later that month to raise money for the Democratic Congressional Campaign Committee and gubernatorial candidate Martha Coakley."

That is three fundraisers in six months just in the city of Boston.

And it doesn't keep happening because of the veep's passion for clam chowder and inscrutable street grids. As the president has a lot of demands on his time, one of the vice president's indispensable roles is to serve as a guy who is available to do these events and make fat cats feel that they are important and listened to. This is anathema to everything Sanders thinks about politics.

Of course, if he were to partner up with someone who shares his distaste for big-dollar politics, they could conceivably totally reinvent the way big-time national politics is done. But Hillary Clinton isn't going to do that. She needs someone who'll fly to Boston, shake hands, chat over drinks, and get some checks.

4) Sanders fans shouldn't want him as VP

Separately from the question of whether Sanders on the bottom half of a national ticket is at all plausible, there's simply no reason for his admirers to hope this happens. Sanders is at his best when he's taking distinctive stands — arguing to replace pharmaceutical patents with prizes or going way off the conventional script to talk about the Nordic social model on network television.

The next vice president of the United States, whoever he or she may be, is going to be singing from the same set of White House talking points as the whole rest of the administration team. Which is probably as it should be. An effective government needs a lot of team players to work. But a healthy democracy also needs outside-the-box thinkers who aren't team players. Sanders is good at that role, and taking him away from it would be sad.