The current claims by the so-called Birther movement that Barack Obama is not a “natural-born citizen” of the United States may seem part of the lunatic fringe. But the Birthers’ basic premise – that the U.S. president is actually the agent of an enemy conspiracy – has a long history in America, and it highlights the tension between American openness and American paranoia.

The name “Birther” seems to be a direct reference to the far right John Birch Society of the late 1950s and early 1960s, whose members claimed that Earl Warren, Dwight Eisenhower, and John Kennedy, among others, were conscious agents of the international Communist conspiracy (and/or the anti-Christ). Robert Welch, a wealthy candy manufacturer, started the Society in 1958 and named it after an American missionary killed by Chinese Communists in 1945 — the first casualty of the Cold War, Welch said. The Birchers were strongest in California, where the organization’s ten thousand eager members stuffed envelopes, walked precincts, and worked phone banks for conservative Republican candidates.

California public officials disagreed over how much attention to give the Birchers. The state’s liberal attorney general, Stanley Mosk, refused to investigate them, calling them a “pathetic” group of “wealthy businessmen, retired military officers and little old ladies in tennis shoes.” But other Democrats, notably Gov. Pat Brown, viewed them as psychopaths and fascists who endangered liberal democracy. Some Republicans, like Richard Nixon in his 1962 gubernatorial race, denounced them; others, like Ronald Reagan, shrewdly repudiated the kookiest ideas of the Birchers but embraced the members.

The possibility of violence always lurked just beneath the surface of this allegedly “pathetic” group. If you accuse the president of treason, you are delegitimating the government and inviting the violent fringe to “save” the republic by removing the traitor.  Contemporaries of the Birchers understood this.  Immediately after President John Kennedy’s assassination, most insiders suspected a right-wing plot. Indeed, Texas businessmen had placed an ad that morning in the Dallas Morning News proclaiming JFK to be a communist agent, and a right-wing mob had attacked and spit upon U.N. ambassador Adlai Stevenson in Dallas just weeks earlier. After Lee Harvey Oswald’s arrest, Jacqueline Kennedy was upset to hear that “some silly little communist” had killed her husband; a fanatical right-wing assassin, she believed, would have invested his death with more meaning.

The Birchers were not the first to believe that the president of the republic actually intended to destroy it. Some FDR-haters, for example, believed he provoked the Pearl Harbor attacks, and held quiet celebrations when he died. And the trend continued into this century, with the 9/11 truthers seeing George W. Bush as a puppet controlled by Dick Cheney, who in turn did the bidding of the military-industrial complex by faking the 9/11 attacks.

The Birther movement melds this recurrent fringe suspicion of the president-as-enemy-agent with good old-fashioned American nativism and racism. Despite the short-form birth certificate posted on line, despite the testimony of Hawaiian officials that the longer form exists in storage in Honolulu, despite birth announcements in both Honolulu newspapers in August 1961, the Birthers contend that Barack Obama is not eligible to be president. (I discuss the birth certificate conspiracy controversy on BBC radio 4 here.)

The Birthers refuse to accept the documentary evidence of Obama’s birth in part because of his race, and in part because he’s “other” in so many ways. Every gift shop in Hawaii prominently features a book called A President from Hawaii , with a cover photo of our biracial president with a lei draped around his neck. To people like Cokie Roberts, who last year criticized Obama for vacationing in his home state, Hawaii is “exotic” and, you know, not really as American as her preferred getaway in Myrtle Beach. When the Birthers say they want their country back, this is what they mean: they feel threatened by a dark-skinned president from what they see as the geographical, racial, and cultural margins of America. Richard Hofstadter and David Brion Davis made this point decades ago in response to the Birchers: American diversity creates American paranoia.  While fluidity has “opened new paths of opportunity,” Davis noted, “it has often been accompanied by feelings of guilt, isolation, and insecurity.”  And fear of conspiracy.

It’s America’s relative openness and tolerance that makes it possible for Barack Obama to become president of the United States. It’s his difference that makes him so exciting to many of us – and so terrifying to the Birthers.