Arthur M. Schlesinger Jr., one of the most renowned and influential historians and intellectuals of the 20th century, died February 28, 2007, after a heart attack suffered in a Manhattan restaurant where he was dining with members of his family.

He was born October 15, 1917, in Columbus, Ohio. His father, Arthur M. Schlesinger, was himself a distinguished historian who inspired his admiring young son, originally named Arthur Bancroft Schlesinger, to change his name to Arthur M. Schlesinger Jr. The senior Schlesinger, having taught at Ohio State University and the University of Iowa, accepted a position at Harvard University in 1924, and Arthur Jr. spent much of the next 37 years in Cambridge, Massachusetts, eventually attending Harvard College. His undergraduate thesis became his first published book, Orestes A. Brownson: A Pilgrim's Progress. In the fall of 1939, after a year studying at the University of Cambridge, he joined Harvard's Society of Fellows, where he wrote one of his most influential books, The Age of Jackson, published in 1944 and the winner of the first of Schlesinger's two Pulitzer Prizes. The Age of Jackson, which challenged the tradition of interpreting the era through the prism of Frederick Jackson Turner's "frontier thesis" and identified the origins of popular democracy as a product of northeastern cities and workers, established him as one of the leading historians of his time.

Schlesinger spent most of World War II in London working for the Office of Strategic Services and then spent several years in Washington, where he began what would become a lifelong role as a prolific writer of essays and articles for newspapers and magazines and as a constant friend and colleague of influential people in many walks of life and many areas of the world. In the fall of 1947, he moved back to Cambridge to accept a position on the Harvard faculty, where he remained for 14 years—now married to Marian Cannon Schlesinger, with whom he had four children. He soon moved out of the shadow of his well-known father and became an important and highly visible person himself—known for his trademark bow ties, his warm and generous personality, his brilliant conversation, and his extraordinary energy. He was a successful and popular teacher at Harvard and an influential figure within the faculty. John Kenneth Galbraith, whom he had met in Washington, also joined the Harvard faculty shortly after the war, became Schlesinger's neighbor in Cambridge, and remained his lifelong friend—and his companion in combining an academic career with an active and unceasing engagement with politics (something Schlesinger shared with his own father as well).

Deeply committed to the future of liberalism, he (along with his father) became one of the founders of Americans for Democratic Action. He was a political ally of Adlai Stevenson and worked on both of his presidential campaigns. He struggled throughout the postwar years to define a path for American liberalism between what he considered the "doughface" progressivism of the socialist left and the reactionary alternatives of the right. His 1949 book, The Vital Center, written in the early stages of what later became known as "McCarthyism," offered a prescription for a dynamic liberalism—a liberalism worth fighting for, he argued—that would move between what he considered these two bankrupt ideologies and would retain ties to liberalism's pragmatic, non-ideological heritage.

During these same years, Schlesinger—a disciplined and indefatigable researcher and writer—worked on what became his enormously influential three-volume study, The Age of Roosevelt. He did not attempt to hide his great admiration for Roosevelt and his belief in his relevance to the politics of the postwar era. At the same time, he offered one of the earliest serious interpretations of the New Deal, identifying it simultaneously as a product of the progressive tradition and as a significant break with the past. He was among the first scholars to argue that there was both a "first" and a "second" New Deal, and he offered a panoramic vision of the turbulent political world of the 1930s and its impact on Roosevelt's political decisions. The first volume of the series, The Crisis of the Old Order, was awarded the Bancroft Prize.

The presidential election of 1960 was a major turning point in Schlesinger's life. He became an early supporter of John F. Kennedy (his Harvard contemporary), worked actively on his campaign, and after the election accepted Kennedy's invitation to serve as a special assistant in the White House, where—along with Theodore Sorensen, John Kenneth Galbraith, Richard Goodwin, and others—he became part of an influential group of liberals within the administration who attempted to steer Kennedy away from the more conservative views of the many committed Cold Warriors in the government of the early 1960s. After the president's death in 1963, Schlesinger served briefly under Lyndon Johnson and then left the government to write an extraordinarily successful account of the Kennedy Years, A Thousand Days, for which he won his second Pulitzer Prize and a National Book Award. A Thousand Days was a frankly personal work—partly a memoir, partly a history, partly an effort to establish Kennedy's legacy as an agent of progressive change both at home and in the world. In these same years, he divorced his first wife, married Alexandra Emmet (with whom he had another son and gained a stepson), moved to New York, and joined the faculty of the City University of New York Graduate School.

Schlesinger continued to play an active role in liberal politics and became a close ally of Robert F. Kennedy, in whose presidential campaign he worked in 1968. After Kennedy's assassination that June, Schlesinger was for a time uncharacteristically discouraged and even bitter. But eventually, he found himself drawn again to writing about a fallen leader whom he had known and admired. Robert F. Kennedy and His Times, published in 1978 and the winner of the National Book Award, was a more conventional biography than A Thousand Days, based on extensive research, and it examined the entirety of Robert Kennedy's life. Although not wholly uncritical, it reflected Schlesinger's view of Kennedy as someone who had developed the potential to become a great leader and who, like his brother, had died before he could fulfill his destiny. While Schlesinger never again served in government or allied himself with an administration or campaign, he remained in almost constant communication with other people of power and influence in many parts of the world, and he appeared frequently in both print and broadcast media as a commentator on public issues. He led an active academic and social life as well.

At the same time, he continued writing and publishing prolifically. "Having perhaps the soul of a hack," he once wrote, "I have never been bothered with writer's block, nor am I unduly distracted by noise. . . . I did not mind the clamor of children and never closed my study door to the life of the household." A bitter opponent of the Vietnam War and of Richard Nixon, he wrote strenuously about both—including a harsh appraisal of the Vietnam War (The Bitter Heritage, 1967) and a strong repudiation of what he considered the dangerous overreaching of the Nixon White House (The Imperial Presidency, 1973). A 1991 essay, published as The Disuniting of America, was a controversial lament about the dangers of "multiculturalism." His last book, War and the American Presidency, published in 2005, was a harsh attack on the Iraq War that continued his long argument against unnecessary and excessive use of American military force.

Schlesinger was a lifelong diarist, and his journals helped him compose a memoir, A Life in the Twentieth Century (2000), the first of a planned but uncompleted two volumes. (An edited version of his diaries is scheduled for publication in fall 2007.) Although the memoir covered only the years to 1950, it conveyed clearly and eloquently the multiple commitments that shaped almost the entirety of his life—a belief in the value of history, a belief in its power to shape ideas and events, and a belief in his obligation to use his knowledge of the past to affect the present. In his last years, he confirmed his continued allegiance to the ideas he had embraced more than a half century earlier and to the value of fighting for them. "So long as society stays free," he wrote in his memoir, "so long will it continue in a state of tension, breeding contradiction, breeding strife. But conflict is also the guarantee of freedom; it is the instrument of change. . . . I am somewhat embarrassed to confess that I have not radically altered my general outlook in the more than half century since the The Vital Center's publication. . . . I have not been born again, and there it is."

—Alan Brinkley, Columbia University