Matthew Dallek, an assistant professor in George Washington University’s Graduate School of Political Management, is the author of “The Right Moment: Ronald Reagan’s First Victory and the Decisive Turning Point in American Politics.”

The Life

By H.W. Brands

805 pp. $35

By 2016, Democrats will have held the White House for 16 of the previous 24 years, enacted national health reform and spent more than $800 billion on a Keynesian plan to stimulate the economy. Some critics charge that Obama liberals have turned America into a socialist state. Among them, former House Speaker Newt Gingrich argued in 2010 that a “secular-socialist machine” was destroying America’s democracy.

Meanwhile, scholars and pundits have insisted that modern politics is best seen as “the age of Reagan,” and the contrast — is America a socialist bellwether or still an anti-statist political order? — could hardly be more jarring. Ronald Reagan remains at the center of the literature on contemporary politics, with works such as “The Age of Reagan” (the title of more than one book) describing Reaganism as the prime driver of public policy and Americans’ negative attitudes toward government’s role in society. The typical narrative says that Reagan cut taxes, rolled back state power and renewed the public’s faith in a strong national defense. Even Barack Obama in 2008 accepted this premise of Reagan’s supremacy and implied that his goal was to reverse Reagan’s legacy of small government and move America in a fundamentally more progressive direction.

In “Reagan,” H.W. Brands, a historian at the University of Texas who has written well-received biographies of other presidents, describes his subject as one of the two great presidents of the 20th century (alongside Franklin D. Roosevelt) because he replaced an age of liberalism with the age of conservatism. Brands, who is sympathetic toward Reagan, has a sharp eye for detail. “Reagan” is an engaging study of a man who Brands says defeated Soviet communism and achieved a halfway economic revolution. Drawing on Reagan’s diary, speeches, statements, letters and memoirs, and on interviews with the president’s aides, Brands tells a briskly paced story broken into 114 brief chapters.

The first third of the book — covering Reagan’s rise to the presidency — is largely familiar. His father was a drunk who, Brand argues, made Reagan reluctant to dwell on the past and emotionally distant from his own children. After graduating from Eureka College in Illinois, Reagan held a series of jobs as a radio sports broadcaster before signing a contract with Warner Bros. to star in films.

Little in his early career predicted that an age of politics would come to bear his stamp. Reagan became a foe of communists when he saw them seeking to take over unions and orchestrating violent strikes in Hollywood. After serving as president of the Screen Actors Guild, he became a spokesman for General Electric, where he celebrated capitalism and denounced communism in what became known as the Speech. His nationally televised address on behalf of Barry Goldwater’s 1964 campaign put Reagan on the path that made him governor of California from 1967 to 1975 and president from 1981 to 1989.

Brands deepens some of the portrayals of Reagan in earlier books by journalists Lou Cannon and James Mann, among others. Echoing Cannon, Brands argues that Reagan “understood that the purpose of politics is to govern, not to preserve ideological purity.” Reagan repeatedly told his chief of staff James Baker that “I’d rather get 80 percent of what I want than go over the cliff with my flags flying.” As governor and president, he both cut taxes and agreed to a series of tax increases. He eased abortion restrictions and strengthened the financing for Social Security through a bipartisan compromise. Most famously, he did a 180-degree turn when he embraced arms control with the U.S.S.R. during his second White House term.

“He was the most persuasive political speaker since Roosevelt, combining conviction, focus, and humor in a manner none of his contemporaries could approach,” Brands says, and part of Reagan’s political genius lay in his ability to revive Americans’ flagging faith in democratic capitalism and the future of freedom, using his optimism to inspire the public. Brands demythologizes Reagan, which, given the man’s inscrutability, is no small feat, and at the same time he makes Reagan’s political strengths abundantly clear.

Using transcripts from National Security Council meetings and summits with Soviet Premier Mikhail Gorbachev, this book makes its most important contribution by showing how Reagan used his humor, personality and convictions to mount a sustained assault on communism. While Reagan “thundered against Soviet perfidy for the television camera . . . the substantive measures he took against the Soviets were remarkably modest,” and the results, Brands asserts, were “scarcely short of brilliant.” In Central America, where Reagan saw an entire region “targeted for a communist takeover,” the president armed the anti-communist contras in Nicaragua and toppled the pro-Cuba regime in Grenada, signaling a new militarism in foreign policy. After branding the Soviet Union an “evil empire” in 1983, however, he began a dialogue with Gorbachev, and Brands, quoting from the conversations, shows a president focused on big policy questions, concerned with his image at home and active in his pursuit of arms-control agreements.

Yet a heavy reliance on lengthy quotations at times overwhelms the author’s voice in these pages, depriving the reader of Brands’s views on Reagan’s impact. At the same time, some of the most crucial questions in any assessment of Reagan’s legacy are either elliptically referred to or virtually ignored: How did his cuts to welfare programs, school lunches and food stamps affect poverty rates, social mobility and race relations during the 1980s? How did his combination of tax cuts and tax increases during his first term affect the recession that caused unemployment to reach 10 percent by September 1982? Why did white, working-class Democrats vote for Reagan in droves in 1980 and ’84, and to what extent did his electoral coalition survive after he left office in 1989? Brands maintains that Reagan “defeated communism definitively, with the help of Gorbachev and George Bush.” But it is unclear why Reagan deserves more credit than Gorbachev (the author of glasnost and perestroika), what role the Soviet economic collapse had and why the decades-long containment policies embraced by presidents of both parties were less vital than Reagan’s actions.

Some significant omissions in this biography make it harder to judge Reagan’s role in the social divisions of the 1980s. The 700-plus pages of text make no mention of his 1980 campaign kick-off speech. Delivered in Philadelphia, Miss., where three civil rights workers were murdered in 1964, the talk invoked the segregationist code of “states’ rights.” Also absent is Reagan’s exploitation of the tale of a “welfare queen” who had allegedly sponged off taxpayer largesse, which Reagan cynically held up as an emblem of big government’s habit of fostering delinquency in welfare recipients. Brands devotes a mere three sentences to Reagan’s appointment of Sandra Day O’Connor, the nation’s first female Supreme Court justice, whose tenure shaped laws on abortion, affirmative action and other hot-button social issues.

In the end, however, “Reagan” persuasively suggests that the idea of the age of Reagan is apt indeed. Although the size of government grew on Reagan’s watch, government also came to be seen by Americans as “the problem,” taxes as too high, regulations as onerous to business; and the concept of spreading freedom and support for military spending became organizing principles in foreign policy in a world where dangers were on the rise even after the Cold War. Reagan’s legacy continues to fuel the ideas and frame the choices facing his would-be successors, and this astute biography is further evidence that the 40th president continues to cast a long shadow over a still largely conservative political order.