As a JFK assassination buff, I learned long ago that it is near impossible to argue with most conspiracy advocates - just as I'm sure that many conspiracists have found it difficult to argue with those who support the conclusions of the Warren Commission.

This happens because most of us have an emotional stake in the argument and can't abide anyone who doesn't  see the "truth" as it has been revealed to each of us individually.

This is where skepticism and reasoned argument must step in and play a role. Constantly challenging one's assumptions is the gateway to knowledge. For those who look at the Kennedy assassination, this is especially true. There are literally hundreds of books that cover every conceivable aspect of the assassination. No one could possibly read them all (given how much crap is being pushed in most of those books, that's probably a good thing). But serious researches have posited serious theories about what happened 50 years ago and who was responsible.

Marc Ambinder writes in The Week about his own conversion from conspiracy advocate to accepting the conclusions of the Warren Commission. He writes of the power of Oliver Stone's "JFK" had on him and how it validated many of his conlcusions:

A year later, the day that Gerald Posner's Case Closed came out, I remember sitting in my high school library waiting for my chance to page through U.S News and World Report, which was serializing the chapter on the "single bullet." I was nervous. Part of me didn't want to read a book that concluded something that was precisely the opposite of what I believed. But, clearly, I wasn't totally convinced, because I wanted to read it in the first place.

I took the magazine and began to read. I can pinpoint the moment when my blinders came off, when my childhood assassination conspiracy fantasies dissolved. Posner pointed out that (a) the president's row of seats inside the presidential limousine were built to be higher than the row of seats where Gov. John Connally and his wife Nellie would sit; and (b) all the photographs of the motorcade entering Dealy Plaza showed Connally sitting closer to Nellie, away from the edge of the car.

And suddenly, the single bullet theory made absolute sense. The trajectory of a bullet fired from the Texas School Book Depository absolutely could have entered JFK's upper back, exited his throat, tumbled through the governor, lodging, finally, in his leg. The two men were perfectly aligned. It was just true. No "in mid-air-mind you, the bullet changed direction." None of that was necessary. If the single bullet theory had to be true — and it did, because no one was capable of firing two bullets at precisely the same "x", one of them hitting Kennedy and the other missing Kennedy and hitting Connally on an angle that passed through JFK's torso — then everything else I thought I knew had to be questioned.

Keep in mind: I was 15. This was a seminal intellectual experience for me. It was my first exposure to the powers of skepticism and reasoned argument.

Posner was given the assignment by his publisher because he didn't think Oswald acted alone. By the time he finished his extensive research, he was convinced otherwise.

Anyone who has seen the ABC News special The Kennedy Assassination - Beyond Conspiracy" knows what Ambinder is talking about when he describes the angle of the single bullet.

Posner and Ambinder had their minds changed because they were broad-minded enough to seriously challenge their own views on the assassination. New information altered their thinking and reasoned argument led to a re-evaluation of their positions.

I have always believed Oswald was the lone shooter in Dealy Plaza but I have gone back and forth over the years about whether or not Oswald was part of a larger plot. When the Dallas policeman's dictabelt recording of a shot from the grassy knoll that the House Assassination Committee said was "proof" of a second shooter was thoroughly debunked, I believed the best evidence for conspiracy went with it. Now comes Ion Mihai Pacepa, a former Romanian secret policeman, who believes Oswald was a KGB assassin.The theory is not new, of course, but Pacepa has some interesting documentary evidence that suggests there may be something there. So once again, my assumptions about the assassination have been shaken.

As a lesson in critical thinking, THe JFK assassination teaches us a lot.