In the agonized debates over how it can possibly be that Donald Trump has such a strong chance of being returned to the White House in 2024, it’s important to stress the ways in which the Trump economy, before the arrival of Covid, departed in positive ways from the trends of the last half-century. Trump’s presidency was a period not just of steady growth and low unemployment, but also of growth that was more widely shared than in much of the recent past — with the strongest improvement in median incomes since the 1990s, wage growth for middle- and low-income workers outpacing growth for the upper class, and the lowest African American unemployment rate in decades.

Some of these trends have persisted, as this newsletter has discussed previously, into the Biden presidency, but they’ve been undermined by inflation and shadowed by rising interest rates, creating an economic picture that’s more fraught than some of Biden’s boosters want to acknowledge. (Even this week’s eye-popping G.D.P. number — third-quarter growth at a 4.9 percent rate — coexists with data showing disposable personal income actually dipping just a bit, suggesting that the post-Covid stagnation in real earnings hasn’t fully broken yet.) Whereas the Trump era was less complicated: For a few short years, the American economy performed in ways Americans once took for granted, closer to the long post-World War II boom than to the decades of recession-punctuated deceleration we’ve experienced since the 1970s.

Lately, I’ve been reading a portrait of that long age of disappointment — “Ours Was the Shining Future: The Story of the American Dream,” a new book by my Times colleague and former podcast sparring partner David Leonhardt. It’s a rich economic history of the post-World War II era, enlivened with both personal anecdotes (including some Leonhardt family history) and biographical sketches of famous or once-famous figures, from C. Wright Mills to Robert Bork and Barbara Jordan, whose ideas illuminate the larger transformations Leonhardt describes.

The book’s argument belongs to a genre, reconsiderations of neoliberalism, that’s somewhat familiar by now but is usually more narrowly polemical, where my colleague offers sweep and detail and depth of historical narrative. And the genre’s entries usually come from predictable “outsider” ideological perspectives, from the far left or lately the populist right, assailing the neoliberal age in the voice of its traditional enemies. Whereas Leonhardt, I think it’s fair to say, is a man of the moderate center-left both in ideological predispositions and in personal temperament, which lends his reconsiderations a more unpredictable aspect and gives some of his criticisms greater heft.

He is, among other things, more fair-minded than some of neoliberalism’s populist critics about the reasons that the United States turned to tax cuts, deregulation, privatization and a more minimal vision of the role of the state from the 1970s onward as solutions to real problems of stagnation and inflation and diminished American competitiveness. He’s alive to the ways that economic history and the progressive moral vision do not always perfectly overlap; the reality that African Americans achieved their greatest economic gains before the full triumphs of the civil rights era, before the era of segregation gave way to the era of affirmative action, makes a crucial subplot in his larger case for the benefits of the postwar economic order.

And he’s more attuned than some writers on the left to the fundamental tensions between the “Brahmin left,” the worldview of the liberal professional class, and the interests of working-class America — not just in the way that cultural issues can distract from liberalism’s economic commitments or undermine its political support, but also in the way that the cosmopolitan moral vision and the interests of American workers may sometimes be in direct tension.

This last point yields his greatest heterodoxy, from the perspective of current-era liberalism: an argument that mass immigration might have more to do with post-1970s wage stagnation than liberal experts like to think (even after the improvement in blue-collar wages under Trump’s anti-immigration presidency), in addition to playing a crucial role in unraveling the trust and cohesion that midcentury liberalism depended upon for its grander projects.

That heterodoxy coexists with a core argument that’s more congenial to Biden administration policy, especially insofar as the Biden White House has tried to adapt somewhat to Trump’s populist critique. Basically, Leonhardt argues that post-1970s America lost sight of government’s crucial role in promoting the democratic aspect of democratic capitalism, and that mass prosperity and widely shared wage gains require not only simple redistribution but also structures that counteract corporate power, elite self-interest and monopolistic entrenchment. What we need, then, is a more mid-20th-century mentality, encompassing everything from direct government investment in technology and industry and public works, to some kind of reinvented labor movement, to a post-Bork approach to antitrust regulation and the new behemoths of the digital age, to a renewal of democratic ambition and capacity in our gridlocked and often-filibustered Congress.

It’s a powerful case, and there are good reasons that parts of both right and left, in Trumpism and Bidenomics, have reached for some version of its post-neoliberal vision. But in the spirit of our podcasting days, let me offer two points of possible rebuttal to Leonhardt’s critique and prescriptions.

First, a libertarian response. In his account of Ronald Reagan and his legacy, Leonhardt argues (correctly) that post-1970s neoliberalism did not deliver either the pace of growth or the seeming equality of opportunity that defined the pre-1970s American economy. And he offers America’s less libertarian, more social-democratic developed-world competitors as a different model, because “inequality has not risen as much in many countries as it has in the United States,” while “broad measures of national well-being, such as life expectancy, fared worse” in America than elsewhere.

But to the extent that broadly shared prosperity depends on having rising wealth to share and redistribute in the first place, the neoliberal American economy arguably deserves a little more credit than this. In terms of per capita income, productivity growth and innovation, our post-Reagan advantage over our major European peers has been robust, and despite occasional talk of convergence, the American edge has pretty clearly increased under neoliberalism. Indeed, even during the post-Great Recession period, the era of life expectancy stagnation that Leonhardt identifies as indicting the U.S. economic model, the American economy went from being close to the same size as the European Union’s to being about one-third larger.

It’s not that we can’t potentially learn things from Europe while seeking answers to our social crisis. But whatever we learn can’t be as simple as our neoliberalism went too far, their social democracy worked out better — unless we’re willing to give up on all the surplus wealth and dynamism that we enjoy.

Moreover, the libertarian reader of “Ours Was the Shining Future” might argue that, to the extent that our own dynamism has been deficient relative to America’s pre-1970s trend, that deficiency reflects not neoliberal overreach but all the ways in which neoliberalism simply failed — in its efforts to prevent the growth of regulation, the capture of government by entrenched interests, the culture of safetyism throttling innovation in fields from medicine to nuclear power.

The recent book by the Reaganite economic writer Jim Pethokoukis, “The Conservative Futurist,” makes an extended version of this argument, tracing our era of stagnation to anti-progress ideologies and the regulatory bureaucracies that gave them the force of law. Leonhardt nods to this case by including, for instance, efforts to remove the “bureaucratic barriers that prevent the construction of new homes, schools and transportation systems” in his list of progress-oriented movements. But the libertarian critic would argue that when it comes, say, to the strangling effect that the environmental review process has on states like California, or union rules on construction in New York, the real neoliberal program has been found difficult and left untried.

Then, finally, the example of Europe also points to a social-conservative response to Leonhardt’s portrait, because of course one force among many driving European stagnation is the collapse of birthrates and the rapid aging of the continent under conditions of secularization and sexual liberation.

“Ours Was the Shining Future” urges liberals to concede some modest ground to cultural conservatives, but apart from its immigration heterodoxies, those concessions are mostly framed as a matter of coalition building and pragmatic political necessity. The underlying liberal social model is assumed to be basically compatible with the widely shared prosperity Leonhardt seeks.

But is it? To some extent, the deep trends that he bemoans are rooted in social liberalism itself. The slowing of growth is connected to the retreat from marriage and family, which has most of the developed world headed for demographic autumn, in which economic stagnation may be cemented by senescence. The socioeconomic inequalities of post-1970s America are connected to widening inequalities in post-1970s family structure, the rise of out-of-wedlock births and single-parent families that so many progressives are so conspicuously loath to treat as a matter of real cultural or political concern.

It’s not that conservatives have a clear solution to these dilemmas (regular readers will note that I have not yet delivered a recently promised newsletter on plausible conservative responses to marriage’s decline!), or that they’re in any way resolved simply by electing right-wing governments, whether in Washington or Warsaw or anywhere else.

But we clearly live in a culture that’s much closer to what social liberals wanted, back when this long era of disappointment began, than it is to any conservative social blueprint. So when liberals reckon with why disappointment shadows us, why the shining future dimmed, the role of their own cultural victories may deserve more attention even than what’s offered by Leonhardt’s broad-minded, self-critical and always interesting account.