In its early months, Bernie Sanders's presidential campaign suffered from the impression that it was a protest candidacy more about discussing issues than about electing a president. More recently, it has looked more like a genuine effort to deny Hillary Clinton the nomination — an effort that seems likely to fail. But judged by that earlier standard, Sanders has been highly successful. I'll use myself as an example: Thanks to Sanders — and specifically thanks to his campaign — I've come around to the idea that the correct tuition for qualified students at public colleges and universities is $0.

If the government is going to be in the business of encouraging people to go to college and spending money on making it affordable, the right way to do that is to make it free.

Donald Trump's kids should get public services too

The traditional case against free college, both in the United States and in other countries where this is discussed, is that it's a waste of money to offer publicly subsidized higher education to the children of affluent parents. Hillary Clinton has made this especially pointed by saying she doesn't want the public paying for Donald Trump's kids to go to college.

It's a decent laugh line, and it does make the underlying policy point correctly. But it also reminded me of the few times in my life that I met Trump's daughter Ivanka. At the time, I was attending an expensive private high school and Ivanka was attending a different expensive private high school, and we had a mutual friend who attended yet another expensive private high school and would sometimes throw parties when his parents were out of town (think Gossip Girl, but with real-life awkward teens instead of gorgeous actors).

None of us was attending school at public expense, but we all could have been as a matter of right and public policy. Which is to say we don't charge tuition at public high schools and then provide grants and loans to make it affordable to families in need. We make it free, and to the extent that we need to consider families' differential ability to pay we do that through the tax code.

One reason is that even though in a narrow fiscal sense it benefits cities that so many of their affluent families send their kids to private school, paying taxes without using the service, in a more holistic sense it's quite bad for public education in the city.

Wealthy elites have formal and informal means of influence wherever you look. When they are invested in actually using public services, the odds that the services will actually be decent go way up. Trying to save money by keeping rich kids out of public school or refusing to build libraries in affluent neighborhoods or having police departments charge a finder's fee when they investigate crimes committed against rich people would be penny wise and pound foolish.

We should also consider the possibility that a public commitment to subsidizing college without mandating that it be free actually encourages excessive spending on the part of administrators. In static terms, creating a free public service obviously requires more money than a partially subsidized one. But with a firm "this needs to be free" rule in place, administrators are now limited to the amount of money that's actually been appropriated, and if they want more funds for some new initiative they need to explicitly make the case that it's valuable.

People actually understand free college

The most decisive reason to like Sanders's goal of free college, however, didn't become clear until the campaign itself began. The great thing about free college is that people know what it means and some people are excited about it.

Clinton's college affordability plan, a much more complicated compact aimed at the goal of allowing students to graduate debt-free, utterly fails on this score. It is true that her plan is more fiscally progressive — delivering more help to poor students and less to non-poor ones. It is also true that I have never met a person who is excited about this plan, even among people who are excited about Clinton in general.

Sanders's plan, by contrast, is a huge applause line at his rallies and something that Sanders's supporters frequently cite as a key reason they are backing him.

I'm not sold on the implementation details of Sanders's plan, and most people feeling the Bern seem to have no idea what those details are. If Sanders were to actually become president, the idea would need a lot more work. But Clinton's plan seems like it was written by higher education wonks for an audience of higher education wonks. Some of my best friends are higher education wonks, and obviously you need some wonks to seal the deal on any kind of workable legislation. But it's useful to start with some kind of clear big-picture goal that means something to normal people.

The greatest legislative success of the Obama years — the Affordable Care Act — suffers greatly in its political sustainability from the fact that people have such a poor grasp of what it encompasses, how it works, and whom it is supposed to be helping.

The contrast with a program like Social Security, which is worse targeted but much better understood, is stark and instructive. The narrow-targeting way is designed to minimize opposition to new initiatives by reducing their headline costs. But there's something to be said for taking the opposite approach and trying to maximize support by framing your objectives in a way that ensures the people to whom your policy is supposed to appeal actually understand what it is.

Free college financed by higher taxes is clean, simple, and easy to understand, and makes for a totally coherent goal to organize around over a period of years or even decades. If Democrats want to expend more public funds to make college cheaper, which it seems like they do, they ought to focus their efforts around Sanders's banner.