A robust public higher education system? “We’d love to, but we can’t afford it.”

The word “can’t” is doing a lot of work in that sentence.

The ability to afford something is often a choice. I can afford a $50 hamburger, in the sense that I could spend $50 on lunch without triggering financial catastrophe. But I refuse to pay $50 for a hamburger because it’s much more than I think a burger is worth. And if I were to try to buy a $50 hamburger daily, it would do me real financial damage (not to mention nutritional damage) over time. One day wouldn’t matter much, but a new habit would.

Parents in the American middle class know this line of thought well. Can we afford a thousand dollars for Junior’s hockey team? Well, yes and no. Can we afford to get our teenager a new used car? Kinda, sorta, but not really. A new big-ticket expense may be possible in an absolute sense but would require sacrifices beyond what seems reasonable. And it may make managing future expectations that much harder even while draining future resources.

“Afford” carries different meanings. There’s an absolute sense: By no stretch of the imagination could I afford to buy Disneyland. Even if I denied myself literally every other expenditure and I brought all my resources to bear, I wouldn’t have nearly enough. In this example, it’s hardly a crisis; I have no designs on Disneyland.

In cases of medical debt, though, this sense of “afford” can be devastating. The medical system in the U.S. often forces people to choose between their money and their life, but unlike the mugger in the old joke, it does so legally. That’s a scandal for a later chapter.

The more common use of “afford” is relative. Yes, I could swing $50 for a burger in an absolute sense, but I’m not going to because it’s outside what I allow myself to spend in that category. Although it sounds objective and impersonal, it necessarily involves judgment. But that judgment hides behind a scientific-sounding declaration, as if the common use of “afford” and the absolute use have the same meaning. They don’t.

Judgments of affording are one thing when they’re made by the person affected by them. Jean-Jacques Rousseau suggested in The Social Contract that true freedom consists in obedience to a law you prescribed for yourself. In that case, your ability to live your judgment is freedom. When basic needs are met and there’s money left over, you can make choices; the ability to make those choices is a form of power. The greatness of a market economy is that different people can make those choices in different ways, reflecting their own tastes. The terror of a market economy is that basic needs aren’t always met, and economic coercion can be every bit as powerful as state coercion. How many times have you stayed quiet at work when you knew something wasn’t right because you needed that job? If the answer isn’t zero, you’ve faced economic coercion. In a market economy, economic coercion will run rampant; political authority is necessary to prevent economic authority from becoming tyrannical.

The choices that individual people make in their own lives reflect all sorts of factors, ranging from personal taste to the perceived availability of various options to social pressure to unthinking habits. But in many ways, the choices reflect less autonomy than we usually assume. In many small towns, for example, there is one supermarket; residents can “choose” to shop elsewhere, but the cost (in time, money and hassle) makes other options impractical. In most of the country, public transportation is sparse enough that people without cars are often relegated to only the physically closest options, which can then charge accordingly; as James Baldwin put it, it’s expensive to be poor. In those settings, people who can afford cars make the individually rational choice to buy one in order to expand their options.

But those choices reflect external constraints as much as individual preferences.

For a counterexample, look at Manhattan. My son moved there right after college, renting a small fifth-floor walkup (!). It’s much more expensive than an apartment in many other places, but because it’s Manhattan, he doesn’t need a car. The subway and bus systems are good enough to get him where he has to go. Given that option, a car becomes an expensive luxury, easily skipped. He could not have done that in most American cities or suburbs.

There’s no law prohibiting him from owning a car. In the setting of New York City, though, other options are more appealing; he can make a different choice. The city’s uncommonly (by U.S. standards) good public transportation system makes that possible.

His choice reflects not just his own preferences, but the available options as well. Monthly subway fare is far less than a car payment, and that’s before adding insurance, gas, maintenance and parking. Unlike most of the country, his location offers him another choice. Having a solid public option makes it easier to afford real choice.

Put differently, public austerity—the deliberate constriction of public options, often under cover of neutral-sounding language—makes private economic coercion worse. If we want people to have real choices in their lives—choices they could actually afford to exercise—public options are often the most effective way to make that possible. Very few individuals could afford to build mass transit systems themselves, but collectively, they’re cheap. The challenge is political, not economic. It involves recognizing that we are all part of the public.

Because we are. We can afford to recognize that. Increasingly, we can’t afford not to.