In forty years of teaching, the most difficult or at least the most disconcerting question I have been asked came during a summer seminar when I was lecturing on the Constitution and on Lincoln’s attitude towards it. I had been reviewing the various compromises made at the Philadelphia Convention concerning slavery when a student asked, point blank, whether, if I had been there, would I have voted for them. I paused. It was easy enough to explain what the compromises were, why those who made them thought them necessary for the document’s completion and ratification, how the Constitution contributed to the growth and success of the United States, and even how the Constitution itself eventually made possible the abolition of slavery, remaining intact during the Civil War and enshrining the result of the fighting in the Thirteenth, Fourteenth, and Fifteen Amendments. But the student wasn’t asking for history: He wanted to know whether those compromises were rightly made when the future was unknown and could only be a matter for speculation, when one could know only one’s own interests, one’s convictions, the legacy of the past, the circumstances of the present, and abstract right.

Yuval Levin has written a splendid essay in defense of the Constitution of the United States, explaining how it was designed for a political people with serious differences: Far from being the cause of our polarization or an obstacle to overcoming it, the Constitution has within it, not a perfect solution to our conflicts but a proven capacity to guide us in addressing them. “How can we act together when we don’t think alike?” It might sound like a rhetorical question, asked in despair. But actually, he shows us, that’s what the Constitution and the complex of institutions it designs or designates make happen, channeling political impetus by dividing power and responsibility between the federal government and the states and by separating federal power among the branches, legislative, executive, and judicial. It doesn’t create a rigid structure or promote stalemate, much less enshrine the status quo; rather, it ensures that differences are not canceled but allowed to find appropriate expression, promoting coalition if not genuinely common action, though rarely the action any one party considers ideal. “Simply put, in a free and (therefore) diverse society, unity does not mean thinking alike; it means acting together.” It’s a brilliant formulation, if a paradoxical one.

The paradox is that human action supposes human thought; otherwise, it is mere motion, like falling when one trips. It’s natural enough to suppose that for a city or a state to act together its citizens must think alike, and political philosophers from Plato (at least in his Republic) to Hobbes supposed that an analogy could be drawn between the city and the soul or the state and a human being and thus that the polity ought to be ruled by a single mind, a king or perhaps a council that did the thinking for all the rest. Even Rousseau, in working out the logic of modern democracy, attributes to it a “general will,” admitting it is a fiction or a construct while explaining the electoral practices that would make it practicable. Even Aristotle, who does not compare the city to a person, says its citizens in the best regime need “homonoia,” or like-mindedness.

But American constitutionalism does not draw on the naturalistic analogy, at least regarding domestic affairs, and it eschews insistence on “homonoia.” The prohibition on religious tests in the original Constitution, reinforced by the prohibition on religious establishment in the First Amendment, allows for difference among citizens on first principles, even as it supposes agreement on the few political principles articulated in the Declaration of Independence and structured into the constitutional frame. In addition, as Levin points out, by leaving matters of “internal police” to the states and assigning to the federal government responsibility only for commerce and defense—and, especially after the Civil War Amendments, protection of many individual rights—it allows for political diversity, for example on questions of public safety, health, morals, and education, traditionally described as the parameters of the states’ police power. At the same time, the Founders supposed that commerce—together with the unimpeded flow of people across state lines, itself guaranteed by the Constitution—would knit the states together and probably lead them to become more alike over time, even as westward movement across the continent would introduce new differences. Unity was to be achieved, not imposed.

Levin insightfully deploys the term “integralist”—resurgent in certain Catholic circles—to describe the alternative arrangement, where thinking alike is the condition for living together, and I suppose that the integralists would call his system “liberal,” as its acceptance of religious liberty and promotion of commercial relations certainly are. But it is also republican, at least in recognizing that political action is possible among multiple minds choosing to act in unison, not usually by yielding to one “decider” but by deliberating together, even when that involves bargaining and compromising, including the compromise involved in accepting defeat after a fair vote. As Levin articulates, the Constitution carefully apportions among the branches responsibility for deliberation, initiative, and judgment, balancing the need for stability and energy, ensuring both the rule of law and the capacity for singular action. Although this is sometimes seen as a mechanism that merely channels the forces of interest and ambition, it is also a means of promoting practical thought, encouraging persuasion as well as the exercise of power. How did we lose sight of this magnificent legacy?

The Progressives were the culprits, Levin argues, at least their leading intellectual politicians, Woodrow Wilson and Theodore Roosevelt, who rejected the Madisonian solution and sought to replace it with presidential leadership of society at large. He writes, “This progressive program is not senseless” and its critique of the Constitution “is not crazy,” but given the constraints of a short essay, he does not elaborate on what was reasonable about progressivism, except perhaps in mentioning “industrialization and the enormous social and economic dislocations of the nineteenth century” and in citing Wilson’s trope about the need to move from a Newtonian to a Darwinian understanding of political life. The Founders, as Levin indicates, anticipated and indeed encouraged economic development and welcomed scientific discovery. Were they hoisted on their own petard? Or was the critical step the novel supposition that moral progress could somehow cancel out the skeptical view of human nature they elaborated, that Kantian disinterestedness could dispense with a sober appreciation of the ineradicable activity of interest in constitutional design, something Kant himself did not imagine? Or, alternatively, that human reason is incapable of the sort of “reflection and choice” by which the Constitution was written, adopted, and reformed?

Again, these are historical questions; Levin’s essay does not dwell on them but moves to the practical question, what is to be done? His proposal to disentangle federal and state responsibilities makes sense, in health and safety and morals as well as education, but since “cooperative federalism” is an artifact not only of economic integration but of federal largesse, it will not be reined in until federal fiscal restraint is recovered. (Its absence, by the way, is an unanticipated consequence of the Sixteenth Amendment, which, in expanding congressional power to tax, likewise expanded the power to borrow, but that is the story for another time.) Cross-partisan bargaining would help return Congress to its deliberative role, but that means addressing why members have ceded power to party leaders and relocated deliberation and bargaining from the floor to the party caucus. “Congressional underreach” is indeed a cause of the instability of administration, where policy in everything from educational practice to environmental protection vibrates violently from administration to administration in the absence of settled law—sometimes checked by the emerging judicial practice of nationwide injunctions coming from district courts and preliminary injunctions issued through the “shadow docket” of the Supreme Court, expanding judicial power in the name of policing constitutional boundaries or protecting constitutional rights. All these suggestions point to Congress and its failings, and I think Levin’s supposition is that they can be fixed without constitutional change if we recover the original recognition that Congress is the branch where the vast diversity of Americans can act together even when we disagree.

I began with the Constitution’s compromises over slavery because today there are many who believe—not without reason—that our differences are as great and the questions of interest and morality just as serious now as when the Constitution was written. I answered the student’s question affirmatively because I believe that our best hope of addressing our differences is through the Constitution—which, after all, can be reformed, as it was on the question of slavery—not by recklessly declaring ourselves in a post-constitutional age, a self-fulfilling prophecy if ever there were to be one. The Constitution succeeded because its drafting and ratification modeled the political virtues—moderation, wisdom, and courage—that proved necessary for its sustainability. It was not constitutionalists like Lincoln but those who rejected the Constitution who brought the country to Civil War, and it was Lincoln’s determined constitutionalism that led the Union to victory and pointed out the way to the reconstruction of unity and peace. While “no cause is ever truly won or lost” in human affairs, the capacity of our constitutional system to allow us to act together even as we think differently seems to me to have been proven beyond a reasonable doubt. What remains in question is whether we still have the virtues—including patience and justice—to work within it, and whether we still recognize living together in peace as a common good.