– Alan Brinkley, an influential historian and academic who traced the evolution of liberalism from the New Deal to the 21st century, died Sunday at his home in Manhattan. He was 70.

The cause was complications of frontotemporal dementia, a neurological disorder, his daughter, Elly Brinkley, said.

One of four children of network anchorman David Brinkley, Alan Brinkley grew up in a home where guests included John F. Kennedy and Arthur M. Schlesinger Jr., and politics, history and culture were all-day conversations. He became a National Book Award winner, Pulitzer Prize finalist and prominent author of two widely used American history textbooks. He also taught at Harvard and Columbia, University, which he joined in 1991.

Liberalism and the forces opposed to it were the themes of much of Brinkley's work. He came of age in the 1950s and '60s, when conservatism seemed so far outside the mainstream that critic Lionel Trilling declared liberalism "not only the dominant but even the sole intellectual tradition." But by the end of the '60s, with the rise of the New Right and divisions among liberals brought on by the Vietnam War and the civil rights movement, critics and scholars were reconsidering their "consensus" that only liberal thought mattered.

"Nothing has become clearer over the past 30 years — both in historical scholarship and in our experience as a society — than that the consensus agreement, on that point at least, was wrong," Brinkley wrote in 1998.

Four years earlier, Brinkley had set off a prolonged debate with the essay "The Problems With Conservatism," in which he called American conservatism "something of an orphan in historical scholarship."

Brinkley was credited with inspiring a wave of new scholarship, although some faulted him for only belatedly noticing conservative books.

New scholarship

From his first book, "Voices of Protest," Brinkley was pointing out the importance of views challenging mainstream liberalism. Winner of the National Book Award in 1983, "Voices of Protest" focused on the 1930s populist leaders Huey Long and Father Coughlin, and how President Franklin Roosevelt responded to their attacks on the New Deal.

"Long and Coughlin were not the leaders of irrational, anti-democratic uprisings," Brinkley wrote. "They were manifestations of one of the most powerful impulses of the Great Depression, and of many decades of American life before it: the urge to defend the autonomy of the individual and the independence of the community against encroachments from the modern ­industrial state."

Brinkley's other books included works on Roosevelt and Kennedy, and a biography of Time magazine publisher Henry Luce that was a Pulitzer finalist in 2011. Brinkley also contributed substantially to his father's bestselling memoir, "Washington Goes to War."

Born in Washington, D.C., on June 2, 1949, he studied at Princeton as an undergraduate and received a Ph.D. in history from Harvard.

As a teenager, Alan Brinkley did try the family business — journalism. He attended the 1964 Republican Convention and had to hide his NBC credentials for fear of harassment from supporters of nominee Barry Goldwater. Four years later, he joined his father at the Democratic National Convention in Chicago, where police assaulted war protesters, and Mayor Richard Daley cursed on national television.

Only 19, Brinkley managed a "scoop" when he confirmed that posters on the convention floor reading, "We Love Mayor Daley" were arranged by the local Democratic Party.

His reporting impressed his father enough that he mentioned it during his nightly broadcast.