As a political centrist in a sharply polarized time, I'm sometimes asked by progressive friends to recommend contemporary conservatives they should read and wrestle with. Then there are the conservative friends who pose the equal and opposite question: Which writers on the left should I seek out to challenge my assumptions?

My answer is usually Corey Robin.

A blogger, essayist, and political science professor at Brooklyn College and the CUNY Graduate Center, Robin is the author of an erudite, bracing, and productively infuriating book about conservatives titled The Reactionary Mind. When the book first appeared, in 2011, its subtitle was Conservatism from Edmund Burke to Sarah Palin. That combination of titles told readers two important things. First, the author treats "conservative" as a synonym for "reactionary." Second, he seeks to subsume Burke, the late-18th-century founder of modern British conservatism, and Palin, the rabble-rousing, trash-talking 21st-century American populist, into a single historical narrative. Could Robin actually intend to draw continuities between such wildly disjunctive figures?

When skeptical readers opened the book, they found that he could and did exactly that. On Robin's telling, every single conservative, reactionary, or counterrevolutionary thinker or actor over the past 350 years, from Thomas Hobbes to Frederick Hayek, from Joseph de Maistre to Ronald Reagan, from John Adams to Ayn Rand, is united in opposing efforts of the "lower orders of society" to emancipate themselves by taking power and privileges away from some entrenched class. Robin notes many of the obvious differences among these political thinkers and actors, including the changing targets of their reactionary ire, but he insists on placing this single anti-egalitarian tendency at the dead center of his study and the conservative tradition he seeks to illuminate.

In the significantly revised second edition of the book that's just been published by Oxford University Press, Robin has strengthened his case, rearranging the chapters and adding three new ones, including one on Donald Trump (who's now replaced Palin in the subtitle). Whether he's writing about Burke or Barry Goldwater, Friedrich Nietzsche or Antonin Scalia, Robin discerns the same "animus against the agency of the subordinate classes," hostility to "the politics of emancipation," and "opposition to the liberation of men and women from the fetters of their superiors."

That few self-described conservatives will recognize themselves in this account doesn't mean that Robin is wrong. Sometimes it takes the perspective of an outsider — and the sensibility of a synthesizer — to perceive certain foundational assumptions and motives buried deep within an ideology, and this is one of those cases. Robin marshals too much evidence from too many seemingly disparate writers and politicians to dismiss his case entirely. He's identified something real and important that readers from all points on the political spectrum would do well to take seriously.

But not too seriously.

That's because Robin's insistence on treating every conservative as a reactionary is a product of his own highly questionable, one-sided assumptions. The most important of these is the view that political ideas and ideologies should be judged primarily, and perhaps solely, on the basis of whether or not they advance or impede justice understood entirely in terms of egalitarian fairness. Is egalitarian fairness an important political and moral ideal? Absolutely. But it's not the only one worth valorizing — and those who affirm other ideals should not be treated like moral and political pariahs.

The tendency to do so is distressingly common on the left.

Consider the research of social psychologist Jonathan Haidt, who has found that those on the left tend to focus on two aspects of moral experience: avoidance of harm toward others, and a concern for universal-egalitarian fairness. Conservatives affirm the importance of both of these as well, but they add three additional concerns that might be described as hierarchical or aspirational moral ideals: loyalty and the threat of its betrayal; deference to authority and fear of subversion; and the longing for sanctity or purity and aversion to degradation. (Religiously oriented conservatives place special emphasis on the last of these.)

Put in slightly different terms, to the horizontal or egalitarian dimension of morality emphasized by the left, the right adds a vertical dimension that encompasses such moral norms, experiences, and ideals as formality, order, modesty, nobility, piety, rectitude, communal solidarity, private and public honor, and steadfast adherence to standards of right conduct and traditional restraints.

These norms, experiences, and ideals are not unique or novel. On the contrary, they connect conservatives morally to many non-Western and traditional cultures. Viewed historically, it's the modern left that's unique in focusing so heavily on the horizontal dimension of morality while directing so much outright hostility to its vertical dimension.

There's a reason why concern for the vertical dimension of morality is so prevalent throughout human history and so stubbornly (and for Robin, ominously) persistent even within the modern West: because the human experience of the world organically generates that concern.

Take the aspect of vertical morality that Robin claims to be key for reactionaries: deference to authority and fear of subversion. Robin treats this as entirely self-interested — an expression of a desire among the members of the ruling class to uphold their own arbitrary power and privileges against those in the "lower orders" who threaten them. But every human society requires that someone — some individuals, some group, some class — serve as an authority entrusted with the power to govern.

This requirement is woven into the fabric of social life, a product of the inequality of knowledge and wisdom within it. Just as we sensibly defer to the authority of doctors when seeking medical treatment and to pilots when boarding an airplane, so it is perfectly reasonable to recognize that some of our fellow citizens are more worthy than others of deference in political matters — and thoroughly unreasonable to think any political community can get away without such deference.

This doesn't mean that the hierarchies conservatives have tended to favor — those based on inherited wealth, military accomplishments, or entrepreneurial achievements — deserve deference. Concern with the injustice (and entrenched mediocrity) of such hierarchies helped to spur support among liberals during the middle decades of the 20th century for meritocratic alternatives that would open the elite strata of society to those formerly locked out of power. But note that meritocracy still presumes that, at any given moment of history, some citizens will be smarter, more worthy of deference, and better suited to rule than others. (Elections presume that too, which makes them less purely egalitarian than the allocation of political offices by lottery, which was the practice in ancient Athens.)

Using Robin's criteria of evaluation, this must mean that meritocratic norms express reactionary impulses, since they continue to uphold some vision of hierarchy and stand in the way of universal egalitarianism. But there's another, more liberal way to look at them — as admittedly imperfect attempts to balance the inextricably conflicting but nonetheless valid demands of political morality.

The greatest minds in Robin's pantheon of reactionaries — Burke, Adams, Alexis de Tocqueville — were conservative precisely in their effort to keep alive and defend the vertical dimensions of political morality that the most radically universal-egalitarian forms of modern politics have been all too eager to stamp out, sometimes in a frenzy of violence.

In his insistence on conflating such writers with genuinely reactionary theorists like de Maistre, Ernst Jünger, and Carl Schmitt, let alone with vulgar, know-nothing demagogues like Palin and Trump, Robin confirms that he belongs to the camp of the radicals, for whom raising even perfectly reasonable objections to the unconditional and conclusive triumph of egalitarianism is considered morally illegitimate.

Liberalism takes a different approach — favoring reforms to make public life more egalitarian while also leaving space within civil society for individuals and groups to uphold and perpetuate non-egalitarian, and even anti-egalitarian, moral ideals and ways of life. That kind of pluralistic harmonization of agonistic moral alternatives (some radical, others conservative) requires the careful practice of an intellectual art of balance.

From a radical writer, liberals will learn about the pathologies and dangers of certain right-wing assumptions and habits of mind. From conservatives, by contrast, they will learn that morality encompasses far more than any true radical will be willing to concede or tolerate.

Corey Robin's The Reactionary Mind does a splendid job of teaching liberals the first lesson while also standing as a vivid and inadvertent illustration of the second.