Any historian of the presidency searches for evidence of motivation and causation. The historian of the modern presidency, therefore, is facing a problem that is growing more and more severe.
Increasingly worried about such political dangers as subpoenas from special prosecutors, newspaper leaks, and memoirs by disgruntled ex-officials published while their ex-bosses are still in office, presidents and their chief officials shy away from putting things on paper. Public figures no longer write the kind of thoughtful, discursive letters and revealing memos that we used to see. People in Washington are more public relations savvy than in earlier times and, thus, more adept at drafting memos and other records that conceal their motives and can fool the historian.
The result of all of this is that a historian of the years of Bill Clinton, George W. Bush, or their successors may not have the kind of sources needed to understand who did what to whom and why as well as a scholar might for, say, the presidency of Franklin Roosevelt. The result of this could be that historical scholarship on future presidents may become, of necessity, more speculative.
In the past, we were able to confidently expect that when we get a decade or more beyond a presidency, we would be able to gain a more nuanced and accurate understanding of a president's motives, perspective, private deeds, and relationships than the inevitably distorted version presented to the public in real time. As scholars of the presidency, we have always presumed that what evidence we lacked about a sitting president would almost certainly later be lavishly supplied, if we only had the patience.
For example, the historian of the FDR presidency can choose from an embarrassment of riches. Before and during his time in the White House, Roosevelt wrote letters that although self-contained, as Roosevelt himself was, were sufficiently revealing and of sufficient literary quality that in 1947, two years after his death, his son Elliott could publish two fat volumes of FDR letters that covered merely the period before his father's election as New York governor in 1928 (Roosevelt 1947-48). At important moments, such as his fateful journeys to meet Churchill and Stalin at Tehran and Yalta, FDR kept diaries that give us brief glimpses into his mind. (1) His wife Eleanor wrote thousands of intimate letters to her husband, other family members, and friends by hand. (2)
FDR's Hudson Valley chum and secretary of the treasury, Henry Morgenthau Jr., kept a detailed diary of his private conversations with the president and had exact stenographic transcripts made of important talks with Cabinet colleagues. (3) Secretary of the Interior Harold Ickes dictated his own 6-million-word journal of his twelve years in office that is notable for its candid, visceral, and often choleric commentary on his New Deal rivals and, sometimes, his boss. (4)
Later presidents and their entourages have left us sources of similar importance. Harry Truman kept a sporadic journal that rivals Ickes's for its acid candor, as do his often-angry unsent letters that are preserved in the Truman Library. Dwight Eisenhower liked to think by writing letters. His missives, some running many pages, to his high school friend "Swede" Hazlett, who still lived in Ike's hometown of Abilene, Kansas, give us important insights into his thinking about issues like arms control and domestic politics. (5)
John Kennedy taped key meetings and conversations, especially during struggles like the battle to integrate the University of Mississippi and the Cuban Missile Crisis. He also dictated real-time accounts of important episodes for his memoirs, such as his oral memo to himself after the U.S.-backed coup against South Vietnamese President Ngo Dinh Diem in 1963 that led to Diem's murder. (6) Lyndon Johnson and Richard Nixon, of course, carried secret presidential taping to unprecedented extremes. …