For the past 3 1 / 2 years, the United States has been conducting a troubling experiment. Despite presiding over a government rooted, by design, in a powerful executive, the current occupant of the White House has steadfastly refused to exercise presidential leadership. Yes, he wields power — for its own sake and for his own sake. But he does not comfort the afflicted, inspire us to national purpose or summon the better angels of our nature. On key matters of policy, the head of the Republican Party evidently does not read or think deeply. In a word, he does not lead. As the writer and popular historian Jon Meacham observed in January 2018: “This is what government would look like without a president.”

That America should lurch along as though it has no president is disconcerting in good times; it is disastrous in a period of pandemic, police violence and public rebellion. Yet as Steve Benen argues in his new book, our current leaderlessness is no momentary aberration, the temporary consequence of an unexpected election result and a uniquely unqualified and incompetent president. Instead, Benen suggests, President Trump is the logical and perhaps inevitable culmination of more than a decade of atrophy within the party he leads.

The Impostors: How Republicans Quit Governing and Seized American Politics” lays out Benen’s indictment that today’s Republicans are a “post-policy party.” The argument builds on, yet departs from, the political science concept of asymmetric polarization — the claim that the GOP has become more extremely conservative than the Democratic Party has become extremely progressive. Less concerned about ideological sorting, Benen shifts the focus to consider the parties’ approaches to policy and governance itself. Since the first decade of this century, he charges, the GOP has become indifferent to “the substance of governing.” On issue after issue, Republican leaders have abandoned policy details for campaign rhetoric, dismissed scientific evidence, eschewed substantive analysis and placed political point-scoring above leadership.

Despite its obvious partisan bent, “The Impostors” seeks to do more than ridicule, shame and condemn. At its heart, the book is a plea for saner heads to rescue the Republican Party from its current morass. Most American voters, Benen argues, “have some expectations that the nation’s two major parties will at least try to work cooperatively and with a sense of shared purpose.” If GOP officials can “recognize their post-policy shortcomings and take steps to correct them,” they can deliver on that wish for functional bipartisan governance.

At the same time, the book is clearly designed to enrage sympathetic readers. As a producer on “The Rachel Maddow Show” on MSNBC, Benen has a knack for comprehensive — if at times excessive — policy detail and a keen eye for intrigue and choice quotes. He has culled years of reporting to present a greatest-hits-style review of Republican intransigence, dissembling and willful ignorance. In eight policy-centered case studies, he painstakingly reconstructs the past 12 to 15 years of American political history on issues from health care and immigration to budgets and taxes, from Iran and North Korea to guns, abortion and civil rights.

Indeed, the chapters quickly fall into a predictable pattern. In the first half, during Barack Obama’s presidency, post-policy Republicans approach the chosen policy issue in bad faith. They demonstrate both factual ignorance (as when Sen. Jim Inhofe of Oklahoma threw a snowball on the Senate floor to try to disprove climate change) and rabid, knee-jerk opposition to Obama (like scheduling dozens of votes to repeal the Affordable Care Act without offering any replacement). And then, just when it seems that it can’t get any worse, the 2016 election happens and Trump deploys a combination of hatred, bravado and incoherence to make an already dysfunctional state of affairs immeasurably worse.

Adhering to standard journalistic practices, Benen refrains from stating that the president of the United States is objectively unintelligent. He nevertheless strongly implies it. On issue after issue, Benen cites Trump’s tweets, off-the-cuff remarks and interview transcripts that highlight contradictions, incongruities and other head-scratchers. In a typical example from 2016, then-candidate Trump appeared to simultaneously praise Obama’s record on deportation and promise to enforce the laws “perhaps with a lot more energy.” As Benen sums up: “Trump didn’t know or care about public policy. . . . He couldn’t answer questions about basic substantive details because he’d evidently given them very little thought.”

Through countless ripped-from-the-headlines examples, “The Impostors” paints a grim picture of a political party in which the kids have taken over the grown-up table and the responsible adults are nowhere to be seen. While Benen makes a strong case that the Republicans have become a post-policy party, he comes up short in offering a compelling explanation for why this occurred. Perhaps it is self-evident that political leaders reared on the anti-statist rhetoric of modern conservatism would take seriously tax reformer Grover Norquist’s famous wish to shrink government so much that he could “drown it in the bathtub.” Yet understanding this journey from slogans to a willful refusal to engage in the policy process is a crucial question of our time.

The modern conservative movement emerged in opposition to Franklin Roosevelt’s New Deal but split, merged and expanded in the decades since. Cold War geopolitics and the civil rights movement, and more recently the neoliberal turn and the rise of working-class populism, have all created opportunities and challenges for organized conservatives. And in the past two generations, as the ideological sorting of American politics reached its culmination, conservatism found a firm institutional home in the Republican Party.

For generations, historians and political scientists have argued over how to explain conservatism and the modern GOP. Important debates surround conservatives’ intellectual roots, their most effective mobilizing strategies, and the respective roles of ideology, class, racial status and material self-interest within conservative politics.

All these scholarly discussions, however contentious, start from one key assumption: that a clear set of traditions, values or priorities sits at the core of Republican politics. While scholars may disagree about the relative importance of the populists, the plutocrats, the racists and the moralists, they assume that the party’s actions can be explained by the interplay among them. This is precisely the presumption Benen challenges. Searching for an internal coherence, grand strategy or intellectual project is a fool’s errand, he concludes. When it comes to a post-policy party, there is no there there.

The Impostors

How Republicans Quit Governing and Seized American Politics

By Steve Benen

William Morrow 374 pp. $28.99