When I went to college in the late 1970s, a few of my professors still referred to female students as “girls.” Many of us spoke of Asian people as “Orientals.” And a physical education instructor taught me to shoot a basketball with a flick of the wrist that we called the “faggy wave.”

But I also engaged in lengthy debates -- inside and outside the classroom -- over abortion and affirmative action. Everyone understood that these were hotly contested questions in American society. So we assumed that they should be vigorously debated at American colleges, too.

It’s rare to hear outright slurs against women or minorities on campus today, which is a very good thing. But we also don’t encounter a full range of opinion about controversial public issues, especially those dealing with race and gender. And that’s because of political correctness, which comes in two very different forms that we too often confuse with each other.

Political correctness one (PC-1) aims to change our language for describing human difference, so it doesn’t demean others. When a professor calls his female students “girls,” he’s implicitly questioning their membership in the adult community. It’s a matter of basic decency to use another term.

It’s also a way of helping all of us to communicate across our differences. If you want to have a substantive conversation with an Asian person, calling her “Oriental” isn’t a good way to start. It’s better to follow a few simple PC-1 rules, which signal the mutual respect that real dialogue requires.

By contrast, political correctness two (PC-2) inhibits that dialogue by imposing liberal political orthodoxies. It’s not just about using the right words, so that everyone feels included and respected. It tries to promulgate a set of right answers, thereby constraining our discussion of important questions.

Consider affirmative action, which remains the great undebated issue in American higher education. According to a 2006 survey by sociologists Neil Gross and Solon Simmons, which they reported in Professors and Their Politics (Johns Hopkins University Press, 2014), 43 percent of American professors oppose race-based affirmative action in college admissions. But you almost never hear them speaking out against it, because -- yes -- it has become politically incorrect to do so.

On abortion, meanwhile, a 2005 study reported that 84 percent of professors were “strongly or somewhat” pro-choice. But that means about one out of seven professors was opposed to abortion rights. And you wouldn’t know that from listening to our dialogues on campus, where most pro-life faculty members keep quiet.

Likewise, our students have learned to bite their tongues if they dissent from PC-2. Every semester, conservative students “come out” to me in their essays and exams. When I urge them to share their views in class, their reply is always the same: we’ll be ridiculed or shouted down.

In a 2010 survey asking college students whether it was “safe to hold unpopular positions on college campuses,” only 40 percent of freshmen “strongly” agreed. And just 30 percent of seniors did so, suggesting that students feel more constrained by PC-2 the longer they are in college.

Of course, PC-1 imposes constraints of its own. So what? It should be politically incorrect to call grown women “girls” or Asians “Orientals.” Listening to Donald Trump and his followers, you might think that these new terms represent a totalitarian threat to American liberties. But it’s hard to see how Trump -- or anyone else -- is harmed when we ask them to use a more respectful vocabulary for describing their fellow citizens.

The real harm arises when we try to enforce the revised terminology with official sanctions and penalties. In their zeal to promote PC-1, too many of our colleges and universities have enacted speech codes that bar insulting or offensive language regarding race, gender, sexuality and more.

Every court that has examined these codes has found them unconstitutional. Speech codes make slur-spouting bigots into First Amendment martyrs. And they reinforce the real danger to free speech on campus, which is ideological rather than linguistic.

If a college bans racist statements, critics of affirmative action will be less likely to speak their minds lest they stand accused of racism themselves. If it bars sexist comments, anti-abortion voices will be constrained. And if homophobic speech is prohibited, faculty members and students who oppose same-sex marriage will be discouraged from sharing their point of view. That can’t be good for our colleges or even for the liberal causes that so many of us hold dear, which can only benefit from a full and complete debate.

Terms like “Oriental” and “faggy wave” inhibit that debate, and I’m ashamed that I ever used them. But I’m also ashamed that many of our colleges and universities have created new restrictions on opinion that stifle discussion as much as the old slurs did. The question is whether we can find the language -- and the courage -- to engage in a real debate about the issues that divide us. Politically correct words can help promote conversation. Politically correct pieties will kill it.