It's conspiracy time again, folks. Since the appearance of the new Oliver Stone-Kevin Costner film, "JFK," Americans everywhere are re-examining the John F. Kennedy assassination. This is partly because Stone is such a famous director, but more because Americans love conspiracies and have never been able to believe that Lee Harvey Oswald was a lone gunman.

So every few years, we take a new look. In 1982, Oswald's grave was opened so that his remains could be positively identified after rumors persisted that Oswald had a double and that an imposter was buried in the grave.All presidential assassinations are not this controversial, of course. No one has lost much sleep over the methods or the murderers of Presidents Garfield and McKinley.

We still worry plenty about how Lincoln died. According to historians, John Wilkes Booth, a well-known actor and Southern sympathizer, organized a group of conspirators with the intention of kidnapping Lincoln and exchanging him for Confederate prisoners held in Northern prison camps. But Booth's accomplices were misfits who botched one attempt and then disbanded.

Booth, on the other hand, remained determined to kill Lincoln. He shot him on April 14, 1865, at Ford's Theatre. Louis Payne, an accomplice, seriously wounded Secretary of State William Seward. But George Atzerodt, another accomplice, assigned to kill Vice President Andrew Johnson, lost his nerve.

Government agents killed Booth in Richard Garrett's barn near Port Royal, Va., on April 26, 1865. Later, conspiracy theories suggested that J.W. Boyd - not Booth - had actually been killed in the barn. Allegedly, government officials knew about it but covered up. Documentary evidence, however, proves that Boyd died in January 1866.

There were also theories that Jefferson Davis, Confederate president, masterminded Lincoln's death, a charge that was discredited - along with another that a power-hungry Andrew Johnson, who succeeded Lincoln as president, was behind Lincoln's murder.

Now Oliver Stone has made the JFK conspiracy theories appear palatable by using a charismatic actor, Costner, to play a quite uncharismatic-in-real-life Jim Garrison, a onetime New Orleans district attorney whose theories about the Kennedy assassination were all discredited long ago.

Once again we see the film shot by bystander Abraham Zapruder depicting Kennedy being thrown backward, not forward, by what seems to be the fatal shot. But Stone has also produced new dramatic footage, printed and edited to look like archival material. When pressed he admits that his film is "speculation," "a countermyth to the Warren Commission."

Reminiscent of the Lincoln conspiracy theories, Stone has suggested the government covered up, that Vice President Lyndon Johnson participated in a right-wing, FBI-CIA plot to kill Kennedy because he disapproved of Kennedy's plan to end the Cold War.

As fascinating as they sound, these claims are no more accurate than the Lincoln theories. In post-Watergate days it is much easier to believe government coverups than it used to be. But the real issue here is the continuing American conviction that charismatic presidents elude us.

Because Kennedy's "Camelot" was so attractive, his untimely death immediately placed him in the company of Lincoln. Just as we were convinced that Lincoln would have prevented radical reconstruction, we were equally convinced that Kennedy would have withdrawn American forces from Vietnam.

We refuse to believe that an all-powerful father figure could be taken by a lone, mentally unbalanced assassin. It is easier to accept the sacrifice of his loss if we believe that the president died at the hands of evil conspirators acting out a specific ideology - even if it isn't true.