In these confounding times, conservatives would do well to recall that modern conservatism is a creature of confounding times. Both the broad school of politics that emerged in England in the 17th and 18th centuries and the mature, post-World War II American variant arose to combat new threats to freedom -- and freedom’s moral, cultural, and religious preconditions.

That’s well and good, many in and outside of the movement will say, but conservatives have never faced a challenge quite like President Donald Trump.

On the one hand, the victories keep rolling in. The Supreme Court’s just-concluded 2017-2018 term culminated with important First Amendment decisions protecting religious liberty and free speech. These narrow rulings were supported by the votes of Trump-appointed Justice Neil Gorsuch. Justice Anthony Kennedy’s retirement gives the president and the slender majority of Senate Republicans an opportunity before the November midterm elections to form a solid bloc of five high-court justices devoted to interpreting the Constitution rather than imposing their judgments about wise policy. Along with tax reform, deregulation, border security, and a determination to take America’s side in foreign affairs, Trump’s first 18 months in office have checked one box after another on the conservative wish list.

On the other hand, Trump remains a dubious captain of conservatism. He is neither schooled in conservative ideas nor a product of the movement. His gaudy private life, which he has flaunted publicly, and his crude political rhetoric fly in the face of moral virtues cherished by social conservatives. His attacks on free trade and embrace of protectionism flout the strictures on limited government and free markets espoused by economic conservatives. His erratic management style saps the energy and shakes the stability that constitutional conservatives consider essential to good government. And his attitude — fluctuating between insouciance and scorn — toward long-standing American diplomatic alliances and the U.S.-forged post-World War II international institutions imperils the global order of which the United States is a chief beneficiary.

That so unlikely a figure has nevertheless advanced a multiplicity of conservative causes bolsters the populist conviction that powered him to the White House: Only a disruptive outsider could rescue the public interest by shaking up a smug Washington elite that extends across the partisan divide.

Yet keeping the country on the right track depends not only on populist ire but also on loyalty to enduring principles of liberty and to the practice of prudent statesmanship. Anxious conservatives as well as impatient populists wonder whether the alliance Trump has built between conservatism and populism can hold.

Although it does not so much as mention Donald Trump, Roger Scruton’s new book, “Conservatism: An Invitation to the Great Tradition” suggests that modern conservativism provides intellectual resources to meet the challenges of the moment. That’s because harmonizing clashing impulses and conflicting principles has always been at the heart of modern conservatism.

A senior fellow at Washington’s Ethics and Public Policy Center, a fellow of the British Academy and a fellow of the Royal Society of Literature, Scruton is the author of more than 40 books on philosophy, aesthetics, and politics. He has long played a leading public role in Britain’s culture wars, defending the nation’s traditions of liberty, learning, and culture. For the sin of speaking highly of the British legacy of freedom and of Western civilization more broadly he has long been a target of opprobrium for his country’s university and media elites. Through it all, he has maintained his grace, good humor, and dedication to conserving conservatism — a task, he compellingly argues, that is inseparable from conserving freedom.

Scruton’s new book provides an outstanding short history of modern conservatism. Published amid the most recent round of controversy about conservatism’s prospects, his masterful survey of the varieties of modern conservatism in Britain, France, Germany, and the United States offers an antidote to the partisan posturing and frenzied overstatement that dominate public debate.

His core claim is that modern conservatism arose as a correction to classical liberalism. Before, say, John Locke gave seminal expression to the idea that human beings are by nature free and equal and that government’s primary task is to secure their individual rights, conservative thinkers assumed that political authority descends from throne and altar. In contrast, the tradition of modern conservatism — as developed in the 18th century in the writings of British jurist William Blackstone, Scotsmen David Hume and Adam Smith, and English statesman Edmund Burke — presumes that political authority arises from the consent of the governed.

Modern conservatism did not seek to bury individual liberty, limited government, free markets, and robust civic association but to save the tradition of freedom from the narrowness of view and destabilizing extremes to which it tends.

For conservatives, “all disputes over law, liberty and justice are addressed to a historic and existing community,” Scruton writes. “The root of politics, they believe, is settlement — the motive in human beings that binds them to the place, the customs, the history and the people that are theirs.”

Modern conservativism recognizes that our political inheritance requires adjustment to changing circumstances and must be open to improvement in light of new experience and gains in knowledge. Following Burke, Scruton affirms that “we must reform in order to conserve” but stresses that reform must be guided by an understanding of who we are and what we have achieved. Conservatives do not reject the Enlightenment’s universal principles — indeed, such principles occupy a place of honor in the tradition of freedom — but rather insist that they must be interpreted through “local history” and “acquired obligations.”

Accordingly, in Britain and the United States today, “conservatives are emphasizing the defense of the homeland, the maintenance of national borders, and the unity and integrity of the nation.” The devotion to homeland and nation, Scruton maintains, “is also a point of tension in conservatism, today as it has been in the past, since belief in a free economy and free trade inevitably clashes with local attachments and community protections.”

In fact, the points of tension are many and enduring because modern conservatism views dedication to moral virtue, family, nation, and faith not as alternatives to freedom but as indispensable to its preservation.

The modern conservative tradition also focuses on the pre-political attachments — “something stronger than politics” — that bind liberal democracies. “There is a ‘first person plural’, a pre-political loyalty,” observes Scruton, “which causes neighbors who voted in opposing ways to treat each other as fellow citizens, for whom the government is not ‘mine’ or ‘yours’ but ‘ours’, whether or not we approve of it.”

Without this pre-political loyalty — the fraying of which connects Brexit and Trump — we cannot hope for politicians to respect the interests of those who did not vote for them, or for citizens to honor the actions of representatives for whom they did not vote.

“My own view,” Scruton writes in conclusion, “is that conservatism will be a necessary ingredient in any solution to the emerging problems of today, and that the tradition of thinking that I have outlined in this book should therefore be part of the education of all politicians everywhere.”

One may add that the tradition devoted to conserving freedom is seldom taught in American universities but is inseparable from a genuinely liberal education. Such an education would make our confounding times less confounding.