In one of Victor Serge’s last works, The Case of Comrade Tulayev, written over fifteen years ago, the Russian equivalent of the Oswald story is set forth. An alienated young man, unhappy with the many aspects of his life in the Soviet Union - the food, his room, his job, etc. - acquires a gun, and manages to shoot Commissar Tulayev one night when he is getting out of a car. An extensive investigation sets in, followed by an extensive purge. Millions of people are arrested and made to confess to being part of a vast conspiracy against the government. The actual assassin is, of course, never suspected, since no one can imagine him as a conspirator. He continues to lead his alienated unhappy life, while the government uncovers the great plot.

In contrast, when John F. Kennedy was assassinated, a solution emerged within hours: one lonely alienated man had done the deed all by himself. The investigation by the Dallas Police and the FBI then proceeded to buttress this view, and to accumulate all sorts of details about the lone assassin, some false (like the murder rap), some trivial (like his early school records), some suggestive (like the bag he carried into the Book Depository), some convincing (like the presence of his rifle and the three shells). From its origins in Dallas on the night of November 22, 1963, the career of the theory of a single conspirator indicated that this was the sort of explanation most congenial to the investigators and the public (although the strange investigation of Joe Molina, a clerk in the Book Depository, from 2 a.m. November 23 until the end of that day, mainly for his activities in a slightly left-wing veterans’ organization, suggests a conspiratorial explanation was then under consideration).

The Warren Commission, after many months of supposed labor and search, came out with an anticlimatic [sic] conclusion, practically the same as that reached by the FBI in its report of December 9, 1963, except for details as to how it happened. The Commission, clothed in the imposing dignity of its august members, declared its conviction that one lone alienated assassin, Lee Harvey Oswald, had indeed carried out the crime...

However, the “official theory” was in many ways implausible. It involved a fantastic amount of luck. If the FBI and Warren Commission reconstructions were correct, Oswald had to get the rifle into the building without attracting attention. Only two people saw him with a long package, and none saw him with it or the rifle in the building. He had to find a place from which he could shoot unobserved. The place, according to the “official theory,” was observed until just a few minutes before the shooting. He had to fire a cheap rifle with a distorted sight, old ammunition, at a moving target in minimal time, and shoot with extraordinary accuracy (three hits in three shots, in 5.6 seconds, according to the FBI; two hits in three shots in 5.6 seconds, according to the Commission). If the “official theory” of the Commission is right, Oswald had no access to the rifle from mid-September until the night before the assassination, and had no opportunity whatsoever to practice for at least two months. Having achieved such amazing success with his three shots, Oswald was then somehow able to leave the scene of the crime casually and undetected, go home, and escape. But for the inexplicable (according to the “official theory”) Tippit episode, Oswald might have been able to disappear. In fact, he did so after that episode, and only attracted attention again because he dashed into a movie theater without paying.

The critics have argued that the Commission’s case against Oswald, if it had ever been taken to court, would have collapsed for lack of legal evidence. A legal case would have been weakened by sloppy police work (e.g., the failure to check whether Oswald’s gun had been used that day), confused and contradictory reports by witnesses (e.g., the mistaken identification of Oswald by the bus driver), and questionable reconstructions by the Commission (e.g., testing the accuracy of the rifle with stationary targets). The Report (against the better judgment of at least two of the Commission’s staff, Liebeler and Ball) had to rely on some of the shakiest witnesses, like Brennan and Mrs. Markham. It also had to impeach some of its best, like Wesley Frazier.

I have documents indicating that U.S. intelligence agencies had a laboratory producing robot murderers (Manchurian Candidates) and that at least one of them took part in the assassination of John F. Kennedy. The programmer of this robot murderer is presently at large. I will provide the information to you at your convenience.

First thing in the morning, CBS News calls (Richard Popkin) about a possible interview with Daniel Schorr. The professor is inspired to the phone once more. Bill Turner, onetime FBI man turned assassination scholar in San Francisco, apparently agrees to serve as bodyguard for the Washington excursion. The bad news is that the stakeout in the Midwest has been lifted for lack of action. There's also some advice from Bernard Fensterwald, the Washington lawyer with such diverse clients as James McCord and James Earl Ray.

"Fensterwald says I'm crazy to go into the President's office with Gregory," the professor is telling me in the car. "He thinks Gregory might tell the President about flying saucers or something. But I'm too committed to Greg. Fensterwald is my lawyer, I want his advice, but there are times I must make up my own mind."

More bad news. The National Tattler has apparently gotten a call from a Russian¬sounding name with a bad conscience and sent its reporter "off to God-knows where to meet him. There's every reason in the world now for the real assassins to send these guys on a wild goose chase."

We are driving to the office of his local lawyer. Roger Ruffin, the man who put financier C. Arnholt Smith behind bars. A quick trip to talk about the foundation. One of Ruffin's secretaries has found a key to the professor's safe deposit box in the parking lot, where he had lost it earlier. The professor is grateful.

Back at the house, a call to Donald Freed in L.A. to compare notes about hypnotized assassins. Freed, co-author of Executive Action with Mark Lane, has a new book coming out about the programming of Sirhan Sirhan.

"I stayed up until 4:30 last night marking passages in the documents for you," the professor tells him. "Just don't get your movie out before I get my story out!" (Freed is seeing Orson Welles these days about movie rights.)

Outside, the ocean breezes sponge the air. A few students are dropping by once again, veterans of Watergate. That means they spent hours in the professor's garage helping clip and file the newspapers. It's getting dark when the doorbell rings again and, casually, Julie goes to answer it. The professor turns to me confidentially, whispering: "Don't you think she should be a little more careful?"

All perspective is fading. I remember a conversation about ex-neighbors, how Barry Goldwater used to haunt La Jolla and Earl Warren even lived next door. I remember the professor wondering aloud: "Is Care CIA?" I remember the Midwest stakeout starting up again with some students from the New German Critique, a radical journal.

The last thing I recall is sitting on my bed transcribing a taped interview with a CIA man about murder attempts on Castro. The professor is on the floor below, sifting through reams of files. A car is screeching up outside. Anxiously, I peer out the windows. I walk around in a zombie - like state checking that all the doors are locked.

Another book published during this period was The Second Oswald by Richard Popkin. It was a short book, only 174 pages including nine appendices, and first appeared in condensed form in the July 28, 1966, issue of The New York Review of Books.

Most of the critics had never heard of the author. "Who is Popkin?" Harold Weisberg asked Sylvia Meagher in August. Popkin was then the chairman of the Department of Philosophy at the University of California in San Diego; he had previously published a book called The History of Skepticism from Erasynus to Descartes.

Ostensibly, Popkin's article was a review of Whitewash and Inquest. Popkin acknowledged that the former was the first critical study of the Commission's case based on a close analysis of the twenty-six volumes, but said its power was diminished by its noisy and tendentious tone. Inquest, on the other hand, was "a remarkably effective book" that explained how the Warren Commission's main objective was presenting a politically acceptable account of the assassination.

But the thrust of Popkin's article was a theory he felt explained the assassination based on the available evidence. The first-generation critics - and here Popkin meant not just Weisberg and Epstein, but Vince Salandria, Fred Cook, Sylvan Fox, and even Thomas Buchanan - did little more than raise questions that the Warren Commission had left unanswered. An alternative explanation was needed. As Allen Dulles had commented, if the critics had found another assassin, "let them name names and produce their evidence."

The solution offered by Professor Popkin was what he called the "second Oswald" - a scenario derived from the official evidence suggesting that someone might have been impersonating Lee Harvey Oswald in the weeks and months before the assassination. The twenty-six volumes, Popkin wrote, contained numerous reliable reports placing Oswald in one location when equally reliable reports placed him elsewhere at the same time. Toward what end? "Critics have brought up the second Oswald as an insufficiently explored phenomenon that might throw light on the case.

One of those critics was Harold Weisberg, who during the summer of 1966 was beginning to feel more optimistic about his work. Whitewash was about to be serialized in a Spanish newspaper and was selling well enough for him to have another five thousand copies printed. He also felt the attitude of the American press was beginning to change. He was being called more often to make speeches and to appear on radio and TV.

When Weisberg read Popkin's article, he concluded Popkin had stolen his work. An entire chapter in Whitewash was devoted to what Weisberg called the "false Oswald," which he said proved there had been a conspiracy. Popkin's plagiarism was so obvious, Weisberg told Sylvia Meagher, that even her old associate Curtis Crawford had mentioned it to him.

Meagher thought the allegation was absurd. "I am amazed at the suggestion that any plagiarism was involved," she told Harold. "What do you refer to? I am very careful always to take into consideration parallel discovery and reasoning, which is widespread among critics of the WR and almost inevitable."

Weisberg declined to elaborate. But this was not the first time he had lashed out at other critics, and it was a cause of some concern for Sylvia; she was beginning to think Weisberg suffered from a persecution complex. The previous spring Weisberg had clashed with Vince Salandria after concluding Salandria could have placed a review of Whitewash, but did not, in Liberation. He had also been angry with M.S. Arnoni, who had dismissed Whitewash as having nothing new. "You are much too conceited about your book," Arnoni told him. Weisberg challenged this, but Arnoni would not be drawn into a debate.

Forswearing philosophy for a spell in the 1960's, Dr. Popkin joined the chorus of doubters who prominently disputed the Warren Commission Report on the assassination of President John F. Kennedy. In an article in The New York Review of Books and in a paperback he argued that the commission's single-assassin solution was not just implausible, but also impossible in terms of the commission's evidence.

The book, "The Second Oswald" (Avon, 1966), promptly came under attack. Eliot Fremont-Smith, in a review in The New York Times, called it "a very hasty book, but fascinating reading."

In the field of the history of philosophy, Richard Popkin, who has died aged 81, was best known for his work on scepticism, and especially for his classic study The History Of Scepticism From Erasmus To Descartes (1960).

A professor at the University of California, San Diego, (1963-73) and Washington University, St Louis, Missouri (1973-86), he was among the founders of the Journal Of The History Of Philosophy, and, with Paul Dibon, started the International Archives In The History Of Ideas; he also wrote about the 1963 assassination of the US president, John Kennedy.

The History Of Scepticism revolutionised the received picture of both the history of philosophy and the history of science, by demonstrating the influence, in the century before Descartes, of ancient Greek sceptical arguments about the impossibility of knowing God and the world.

In making his case for this central contribution to the development of modern science and philosophy, Popkin gave attention to the intellectual context of the time, especially the role of religious disputes in the take-up of philosophical scepticism deriving from the discipline's Greek founder, Pyhrro. Instead of treating the history of science and philosophy as a series of breakthroughs by canonical figures, Popkin sought to view the thought of the past from within its own framework...

Popkin also achieved fame with The Second Oswald (1966), the book in which he disputed the findings of the Warren commission that Kennedy was killed by a lone assassin. He foresaw the rise of religious fundamentalism in the United States and the Middle East, contributing an analysis of its American dimension in Messianic Revolution (1998, co-authored with David Katz). He also wrote for a general philosophical readership, with such books as Philosophy Made Simple (co-authored with Avrum Stroll, 1969).

Popkin was an inspirational teacher who gave great encouragement to younger scholars, such as myself. When I first met him, I was struck by his wry sense of humour, and the touch of scepticism that ensured he never took himself or others over-seriously. All who knew him remember his generosity; and he was always good company and an entertaining raconteur.

Richard H. Popkin, a retired professor of philosophy at the University of California, Los Angeles, who became a specialist on skepticism and its history through the centuries, died here Thursday, his family said. He was 81 and had emphysema, which caused him to use a wheelchair.

Dr. Popkin, despite limited vision, had been working on a book about the 16th-century Rabbi Isaac of Troki in Russia, said his son, Jeremy, of Lexington, Ky.

As an author, Dr. Popkin published his most durable book, ''The History of Skepticism From Erasmus to Spinoza," in 1960, and continued updating it through a 2003 edition.

He attracted mainstream readers with such books as his 1966 ''The Second Oswald: The Case for a Conspiracy Theory," about the assassination of John F. Kennedy. In the book, Dr. Popkin strongly challenged the finding of the Warren Commission that Lee Harvey Oswald had acted alone in fatally shooting the president during a 1963 motorcade in Dallas.