The debate about free speech just won't die.

That's mainly because the issues it raises — where to draw the line between protected and restricted speech, what speech to permit and whose speech to proscribe in which spheres of American life — keep coming up in both political and social contexts.

On the political side, Republican legislators and other elected officials in a long list of states — New Hampshire, West Virginia, Oklahoma, Georgia, Arkansas, North Dakota, South Dakota, Mississippi, Missouri, Iowa, and Texas — are taking aim at the freedom of professors at public universities to speak out on political topics inside and outside of the classroom. This builds on efforts undertaken during the final year of the Trump administration, now continued via legal fights pursued by conservative activists and groups, to ban certain ideas and arguments (especially critical race theory) from public institutions. In these efforts, the American right is following the lead of conservative populists in Hungary, Brazil, Italy, and elsewhere who have sought to use the power of the state to silence those they consider a threat.

On the social side, the left has been accelerating its efforts to use its considerable cultural and institutional power to impose informal sanctions (ranging from public humiliation to firing and ostracism) on those it judges to be guilty of expressing ideas or opinions that transgress the left's own continually evolving set of moral expectations. The way this typically works is that certain individuals within an organization or on social media single out someone for a morally "problematic" or "harmful" statement, which generates broader outrage. As the indignation grows in size and vitriol, the organization employing or doing business with the transgressor seeks to placate the mob by cutting ties to ("cancelling") him or her, with the punishment supposedly serving as a deterrent to encourage greater moral purity in the future.

Only the first of these (the use of state power to limit speech) can be considered censorship. But both are expressions of increasing censoriousness in American public life, with each side's constriction of speech serving as justification for the other's imposition of greater limits.

The question is why it's happening now. Explanations usually treat the trend as an outgrowth of partisan polarization or the rise of illiberal ideologies on the right and left, and there's obviously a lot of truth in both suggestions. But I think there's also something else going on.

We have stopped believing in reason's power to persuade. The right thinks the critical social theories espoused by many on the left are both wrong and pernicious, but it doesn't expect to be able to convince the left of this view. Hence the move to use raw political or legal power to suppress it. The left, meanwhile, thinks many of those who don't share its premises are motivated by racism and other forms of bigotry that are in most cases untouchable by argument. Hence the move to use moral condemnation to get resisters excluded from social circles and cultural institutions in which they enjoy various forms of power and status.

These examples are themselves expressions of a broader trend we see all around us in our public life: the tendency to skip the work of attempting to change minds in favor of grabbing the power to control what's permitted. The clearest, and oldest, example of this move is the appeal to judges to resolve disputes that resist resolution through democratic deliberation and consensus-building. Instead of the right trying (and likely failing) to convince the rest of the country that the New Deal is a bad idea, it seeks to get the Supreme Court to declare the New Deal unconstitutional. Instead of the left trying (and likely failing) to convince the rest of the country that abortion should be legal, it seeks to get the Supreme Court to declare abortion a constitutionally protected right.

This shift from debating the substance of disagreements to attempting to rule the other side out of bounds — from working to change the minds of those who hold contrary views to shouting "you can't say that!" in their faces — has transformed the character of public debate in recent decades, turning logical and rhetorical strategies familiar from the courtroom into argumentative moves deployed every day in response to ordinary disagreements. Rather than trying to convince the other side of our virtues or their errors, we dodge the challenge, leaping instead to a "meta" level of dispute, hoping some other, higher power will settle the debate by, in effect, making our opponents disappear.

But of course our opponents never disappear. They return another day, appealing to a different set of authorities to get us ruled out of bounds, setting in motion the next round of attempted excommunications.

The utter futility of this outcome suggests that we might be better off abandoning the effort to dodge debates about substance. Instead of attempting to rule our opponents out of line, we might try reasoning with them.

Thankfully, a new book both explains and models how to do it. Don't let the subtitle scare you off. Let's Be Reasonable: A Conservative Case for Liberal Education might sound like an ideological intervention in the interminable battle over the politicization of the humanities on college campuses. That is indeed the book's ostensible subject, but its author Jonathan Marks (a professor of politics at Ursinus College, where we were briefly colleagues) is the furthest thing from a strident partisan.

On the contrary, Marks' case for reasonableness isn't discernibly liberal or conservative, socialist or theocratic, radical or reactionary. It follows, instead, from the simple human experience of realizing that one's opinions about the world, whatever they are, don't arise out of thin air and aren't generated by us from scratch. We pick them up from the world around us, from family, friends, teachers, the broader culture. Given this fact, shouldn't we want to examine these opinions, to test them to see if they stand up to scrutiny? Could achieving genuine freedom and self-awareness require anything less?

But how? Marks rather modestly suggests the best way to do so is to encourage students to state clearly what they believe to be true and insist that they practice the art of listening to what their peers have to say about their own convictions. From there, he urges teachers to show their students how to unearth the hidden premises and implied principles embedded within each other's views, as well as in the opinions of the people and ideas they encounter in their studies across the curriculum, in each case examining them with care for their soundness.

Despite appearances, this pedagogical approach doesn't presume or require blind submission to the authority of reason, which is much better at the critical work of drawing distinctions and pointing out contradictions than it is at constructing rock-solid edifices that can withstand critique. But it does presume a willingness to question one's own pieties and the pieties of others — and to treat this willingness as admirable and its refusal as shameful.

Far from encouraging the formation of new dogmas to replace those newly questioned, Marks implies that an education in reasonableness imparts a salutary humility, opening people up to the remarkable extent to which wise choices depend on the exercise of sound judgment far more than they do on absolutist formulas. Fortunately, the exercise of such judgment is something to which a habit of intellectual humility is especially well suited.

In the end, I'm not entirely persuaded that Marks presents a viable path forward for today's elite universities, since expecting parents to shell out $50,000 or more a year to cultivate reasonableness doesn't seem all that, well, reasonable. But that doesn't mean our country and culture wouldn't be much better off if we followed his arguments and example. We would be — and in no area more so than in debates around free speech.

It may well be that preserving a culture of free speech presumes a certain level of open-mindedness among its members, so that every one of them can trust that free public debate will be conducted and adjudicated in good faith, with each side of every dispute seeking to listen and engage substantively and on the merits with the claims, premises, and implications of the views espoused by the other. When such reasonableness atrophies, so does trust. And with the waning of trust comes an effort to shut down debate for the benefit of one's own side.

That's where we are today. It's hard to see how things can significantly improve without a return to reasonableness.