We can all sense it: the hollowing out of the center, the ever-increasing polarization of our public life. Republicans shift further right while Democrats move further left, leaving much less overlap between the parties (in Congress and in public opinion) than there was from the mid-20th-century heyday of the so-called "vital center" on down through the first decade of the 21st.

Those of us who favor a politics of consensus, conciliation, and the common good are distressed by the trend. But too often our response falls short, amounting to a thin and reactive defense of the center-left and center-right that has held power for decades and increasingly finds itself under siege by an angry populism, as if the way forward should amount to a turn backward toward the deposed status quo.

That's a foolish response — one that grows out of a pervasive refusal to accept the legitimacy of the grievances driving the flight from the center and inflaming populist passions all around us. If there's any chance for a newly revitalized center to recapture the political imagination, it will need to become less defensive, less committed to regaining power without undergoing significant reform, and more willing to reconstitute itself in light of populist objections to the old centrist consensus.

One obstacle standing in the way of an honest reckoning with the centrist failures of the past is the pervasive tendency of populists to make their criticisms in extremely broad terms. It's not just that this or that president or Congress has pursued this or that bad policy. It's the establishment itself — the country's prevailing political norms and institutions as well as the centrist elites who work in and run them — that is to blame. Hearing such charges and seeing them rewarded at the ballot box places these elites on the defensive — and understandably so.

But that doesn't mean the critique isn't partially valid. Until quite recently, the country's main political parties, mainstream media companies, financial institutions, tech firms, and think tanks and other policy research groups have all been overwhelmingly dominated by people who affirm a relatively narrow range of centrist ideas on economic growth, trade, immigration, financial regulation, and foreign policy. That's what lends plausibility to the quasi-conspiratorial accusations favored by anti-establishment populist politicians: It really can seem as if the system as a whole is committed to upholding these specific policies, necessitating an assault on that system as the only way of changing course.

Where the centrist establishment goes wrong is in effectively conceding the truth of this populist accusation by associating its own preferred policies with the requirements of liberal democratic government as such. So favoring free trade, high rates of immigration, and a militarily aggressive approach to international affairs become not only the specific (and contingent) policies that have held sway for most of the past half century but essential correlates of liberal government itself — somehow almost as essential to democracy as the rule of law; individual rights to speech, worship, assembly, and private property; an independent judiciary and civilian control of the military and police; representative institutions founded on the consent of the governed; and free and fair elections.

There is some justification for treating more radical policy proposals as a potential threat to liberal democracy. The further one moves from the center, the more incompatible those political hopes and demands become with liberalism broadly defined, blending into such anti-liberal ideologies as fascism on the far right and communism on the far left.

Yet it's crucial that we resist this easy conflation of the policies favored by the center over the past several decades with the bedrock, regime-level requirements of liberal democracy — first, because liberal government is more ideologically supple than that; second, because such a conflation can be used to justify dismissing what's valid in the populist critique of the centrist consensus.

There's much that's defensible in this critique. Far from vital, the center has become sclerotic, out of touch, unwilling to reflect on its own faults and failures. During the decades when the pro-market center left and center right took turns running the show, wages have stagnated, upward mobility has slowed to a crawl, growth has been anemic, economic inequality has increased dramatically, the manufacturing sector has waned, whole regions of the country have stagnated or fallen into economic and cultural decline, health-care costs have skyrocketed, life expectancy has begun to fall, the country has fought a series of protracted wars to indeterminate conclusions, China has begun to surpass us economically, and the federal debt has grown to levels not seen since World War II. Not surprisingly, during this same period levels of social trust, faith in public institutions, and hope for the future of the country have all collapsed.

Right-wing populists focus on some of these problems. Left-wing populists highlight others. Some of the solutions they propose in response may be poorly thought out, counter-productive, and even flagrantly demagogic. But at least the populists acknowledge the problems as problems and appear willing to take bold action to address them — whether it's protectionism and immigration restrictions or proposals for single-payer health care and an agenda for industrial policy.

Far too often, centrists on both sides seem averse to such boldness, preferring to wait for the populist fever to break in the hope that they'll be able to return to enacting precisely the same mix of policies that got us where we are in the first place, with maybe a cosmetic tweak made here or there.

There is a better approach.

Centrists could embrace flexibility, striving to be much more open to pragmatism, not only about means (which policies work) but also about ends. What do Americans need and want the government to do two decades into the new century? And how might we go about achieving these goals (including paying for the effort)? Those are the questions we need to pose and answer as a society — not presuming we already know the answers (as the old centrists do), and not pitting the preferences and needs of some groups against those of others (as populists prefer), but encouraging a free and open conversation among all Americans as Americans.

Everything is, or should be, on the table and up for debate — except for the rules of the game itself. The norms and institutions of liberal democracy need to be affirmed, preserved, and protected. But the best way to do that isn't to constrict the policy debate to the parameters that have prevailed since the late 1970s. It's to demonstrate to the country, including its most agitated populists, that our norms and institutions are flexible enough to adjust to new realities and respond to new problems — whether it's an ascendant China, the opioid epidemic, or the soaring costs of health-care and college, and whether or not the best solution offends the stultified ideological pieties that have defined the conventional wisdom since before the Cold War came to a close.

If the center hopes to become vital once again, it needs to show that it's capable of forging a new common ground out of a 21st-century vision of the common good.