Here is my Common Sense take on the issue.
The single best argument against Oswald being part of a conspiracy is that he got his job at the TSBD well before anyone knew a presidential motorcade would be going right past that building in late November. Whether one postulates Oswald was a shooter as part of a conspiracy or patsy chosen to take the fall, the plotters couldn't have known that the job at the TSBD would give Oswald a the perfect perch to shoot JFK from. Even if they knew JFK was coming to Dallas, they would have to have specific knowledge that there would be a motorcade and that it would pass directly in front of the TSBD.
The CTs might counter that the conspirators just took advantage of the situation when they discovered their shooter/patsy was at a workplace overlooking the parade route. The question then becomes, why would they have selected Oswald for either role if they didn't know in advance of the golden opportunity his employment at the TSBD would present. Why would these conspirators select an average USMC marksman to do the biggest contract killing in American history? It makes no sense. It is also a bit far-fetched to think they had already contracted with Oswald to do the shooting and just got lucky when the motorcade route was announced. What are the odds of that happening.
Then the CTs might ask, didn't Oswald just get lucky when he learned of the motorcade route. Yes he did, and if Oswald was the only mentally unbalanced person in the country with a rifle and a propensity to commit such a heinous act, it would have been a remarkably bad piece of luck. But the fact is there might have been dozens of such people in the country, maybe hundreds, who would have done what Oswald did if given the opportunity. Given the fact we had a President who traveled all over the country and had a fondness for riding in slow moving motorcades in an open top car, it's not at all surprising that he eventually might cross paths with one of them. The key word here is "opportunity". This was a crime of opportunity. Oswald won the assassin's lottery when JFK's motorcade was routed right past his workplace and he took full advantage. Maybe if another site for the luncheon had been selected we would have never heard of Lee Harvey Oswald. Maybe it would have been another assassin in another city at another time who was dealt such an opportunity or maybe it would never have happened at all. Life can be that random. Who could have guessed that the choice for the site of the luncheon would have such devastating consequences, but that is what happened.
I often challenge CT arguments on the basis
“That simply makes no sense.” Honesty and my own nagging doubts about the LN scenario compel me to acknowledge three CT scenarios at which this challenge can’t be leveled: (1) Oswald as a dupe in a Mafia plot; (2) Oswald as a dupe in an anti-Castro plot; and (3) Oswald as a willing participant in a pro-Castro plot. To make sense, I believe all three would have to be tight, minimalist conspiracies, and number (3) would have to involve pro-Castro types little more sophisticated than Oswald himself (
i.e., nothing official).
For any of these, Oswald with his pro-Castro high profile could have been on the radar screen long before the JFKA. He would have been on the radar screen for numbers (1) and (2) because he would have been an almost too-good-to-be-true patsy. He would have been on the radar screen for (3) because he was an in-your-face Castro supporter (and god knows what wild things he may have said in New Orleans or Mexico City). To be on the radar screen would not have required anyone to know in advance that he would be working in the TSBD or the exact motorcade route.
JFK’s trip to Dallas was known even before Oswald went to Mexico City. There were surely umpteen locations along the route from which the JFKA could have been carried out. I think there is a tendency to reason backwards: Oswald was in fact working in the TSBD, the sixth floor provided an excellent perch, the limousine slowed to a crawl when it turned onto Elm, and the JFKA was in fact highly successful – ergo, this must have been “the plan” from the get-go. But this is not true at all. How do we account for Oswald pretty clearly scouting the Allright Parking Garage just a week before the JFKA?
I don’t say that any of the three CT scenarios I posit is anywhere near as likely as the LN scenario. To tilt the scales would require either or both of (1) really compelling evidence that there was such a plot and that it involved Oswald and/or (2) really compelling evidence that the LN scenario – probably meaning the SBT – is not a plausible explanation for what occurred in Dealey Plaza.
I do say, however, that none of the scenarios is nonsensical or subject to the charge
“That simply makes no sense.” If we’re going to be intellectually honest and accuse CTers of making no sense when that charge fits, I think we have to be careful to distinguish between genuine “common sense” and mere “LN salesmanship.”
One bit of common sense that I think is very difficult for any CT scenario to overcome is:
In any conspiracy, it is hard to imagine a gunman hitching a ride with a coworker to retrieve his disassembled $20 rifle the evening before the assassination. That's a toughie, hence the CT propensity to say "That's not what happened."