‘‘Donald Trump is not a conservative,” declares Andrew Bacevich in the introduction to American Conservatism: Reclaiming an Intellectual Tradition, an anthology edited by the former army officer and Professor Emeritus of History and International Relations at Boston University, and published last month under the authoritative aegis of the Library of America.

It’s not just the nominal Republican in the Oval Office. Other senior GOP politicians, according to Bacevich, “seem to adhere to no worldview worthy of the name”, while “the provocateurs who inhabit the sprawling universe of rightwing media . . .  rabble-rouse and line their own pockets” rather than “promote genuine conservative values”.

What is left of the American conservatism tradition has, he argues, “acquired a reputation as both noxious and intellectually disreputable”. It’s hard not to see Bacevich’s point. Take a look at the agenda for CPAC, the annual conservative gathering that has become a festival of shockjockerry and Trump worship. Or consider the ideological gymnastics many on the right are willing to perform to keep up with the president’s political whims. This is the motley crew from which Bacevich (right) claims to be doing the reclaiming.

Bacevich says American Conservatism is representative of only the “best” conservative writing of the twentieth century according to his own prejudices. Those prejudices include hostility to much of US foreign policy since the end of the Cold War. Bacevich, who is president of the anti-intervention Quincy Institute for Responsible Statecraft, was even mentioned by Politico as a left-field choice for Secretary of Defense in some (extremely premature) speculation about a Bernie Sanders cabinet.

Hence his otherwise puzzling decision to exclude neoconservatives from the anthology, something he signposts in the introduction, claiming that, while they “for a time made a considerable impact on the national conversation and even arguably on US foreign policy, they were never genuinely conservative”.  Confusingly, Bacevich goes on to break his own rule by including an essay by Irving Kristol, the “godfather of neoconservatism”.

Elsewhere, he is ecumenical enough to include liberals like New Republic founder Walter Lippmann, free-range libertarians like Murray Rothbard, and writers who eschew easy categorisation like Wendell Berry and Joan Didion. The volume is richer for these contributions, and for casting a net beyond the limits of “movement” conservatism. But the exclusion of neoconservative authors is churlish, and will leave readers with an incomplete picture of conservative thought on the American right.

That the anthology is steered by Bacevich’s conservatism, rather than anything more broadly representative, is clear from the first sentence: “The modern American conservative tradition — roughly dating from the dawn of the twentieth century — emerged in reaction to modernity itself.” The choice of starting point is eccentric given that conservatism as a self-conscious and organised movement in the United States is very much a postwar phenomenon.

For someone keen to take a longer view, the turn of the century seems an odd cut-off. The characterisation of American conservatism as emerging in opposition to modernity strips it of its Americanness. There may be an anti-modern strain to American conservative thinking, but the striking thing about it compared to its European equivalents has always been a comparative enthusiasm for economic dynamism, a lack of squeamishness about the consequences of creative destruction, and a faith in the rights-based classical liberalism set forth by the US Constitution and Bill of Rights.

Notwithstanding the editor’s licence exercised by Bacevich, the book paints a picture of an identifiably American set of conservative ideas: the vigour with which Theodore Roosevelt makes the case for “the strenuous life” in a speech in Chicago on the eve of the twentieth century; the moral clarity of William Henry Chamberlin’s 1937 dissection of communism in “The Choice Before Civilisation”; the deference to the founding fathers in the legal originalism of Antonin Scalia.

Some of the contributions helped to define the left-right divide in late-twentieth-century America. For example, Allan Bloom’s The Closing of the American Mind, extracted here, set the tone for conservative critiques of relativism and postmodernism in academia. Other essays connect the past with the present.

Andrew Sullivan, the Anglo-American journalist, makes the cut with “Here comes the groom”, his influential 1989 case for gay marriage. (Brilliant though the essay is, I’m not sure if “Sullivan is arguably the most influential conservative public intellectual of his generation”, as Bacevich claims.) Patrick Deneen, a professor at Notre Dame and a very different kind of conservative, whose Why Liberalism Failed has become something of a core text for the new American right, also makes an appearance.

Now is a good time to revisit the twentieth-century currents in conservative thought not because, as some claim, it is moribund as a coherent, serious ideology in America and needs reviving, but because it is alive and well and at an important, remarkably fluid, moment in its history.

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For all that Trump is the cause of the deepest fault line on the American right, that rift can leave the misleading impression that conversations among US conservatives come down to one man. (Indeed, the interestingness of a conservative over here is generally inversely proportionate to the amount of time he or she spends talking about the president, whether they are supporters or critics.)

Away from an exhausting Trumpcentric news cycle are disagreements that reveal an American conservatism neither on its deathbed, as the #nevertrump set — and Bacevich — might claim, nor flourishing in the way the MAGA crowd would have you believe. Instead, it is at a crossroads. Old allegiances have been broken, new ones are being formed and a lot is at stake. The range of acceptable mainstream conservative opinion is dauntingly, invigoratingly wide.

In the search for answers, legal brains and religious thinkers duke it out over the limits to the legitimate use of state power to achieve social goals; new think-tanks and journals push economic ideas that would have felt entirely foreign on the American right a few years ago; China hawks who think a new Cold War is upon us, isolationists emboldened by recent history littered with foreign policy failures, and interventionists worried about a combative Iran scramble over one another for the ear of administration officials.

As the Library of America’s new anthology makes clear, some of this contains echoes from the previous century. But much of it feels genuinely novel. Harvard law professor and leading “integralist” Adrian Vermeule recently made waves with an essay in the Atlantic arguing that originalism — the dominant legal school of thought among conservatives — has outlived its usefulness. Vermeule wants American judges to read “substantive moral principles that conduce to the common good” into the “majestic generalities and ambiguities of the written Constitution”.

He adds, “These principles include respect for the authority of rule and rulers; respect for hierarchies needed for society to function; solidarity within and among families, social groups and workers’ unions, trade associations, and professions . . . and a candid willingness to ‘legislate morality’.”

Integralists want to subordinate temporal considerations like the division between church and state to the higher good. It is hard to overstate the extent to which this constitutes a departure from American conservative orthodoxy.

In the April issue of First Things, a Catholic journal that is home to many integralists, its editor Rusty Reno sketched what he called “a new fusionism”. Fusionism was the glue that held American conservatism together for much of the second half of the twentieth century, uniting libertarians and traditionalists in opposition to progressivism at home and communism overseas through organs like William F. Buckley’s National Review.

The old fusionism emphasised freedom; the new fusionism values “walls, protection, and reconsolidation — solidarity”. According to Reno, “Freedom-solutions increasingly ring false. The greatest challenges in 2020 arise from social disintegration and deconsolidation.” In economics, that means adapting the free market to “provide productive roles for American workers”. In foreign policy it means “a view of America’s global leadership that is clearly organised around the interests of the American people”.

This is by no means the dominant view on the American right, but it is in the ascendency. George Will, the libertarian-leaning Pulitzer-Prize-winning Washington Post columnist, set out a more orthodox expression of American conservatism in his book The Conservative Sensibility, published last year.

He called it “an ongoing meditation on America’s Founding, which means on the Declaration of Independence and on the Constitution, which should be construed in the bright light cast by the declaration’s affirmation of natural rights. The American project, distilled to its essence, was, and the conservative project is, to demonstrate that a government constructed on the assumptions of natural rights must be limited government.”

It is as neat a definition of American conservatism as can be found in Bacevich’s volume. For all its merits, however, it feels more and more dated. It flies in the face of the arguments in vogue among American conservatives today and flies in the face of the convictions of the president. Contrary to Bacevich’s claim that Trump is “no conservative”, there is plenty of overlap between his views and the new thinking on the right in the US. The question worth asking isn’t whether the conservative movement will survive in America, but whether it will continue to feel distinctly American, or whether it will become harder and harder to distinguish from its European cousins.