It may be telling that, in responding to comments to my previous post on remembering JFK's assassination, I twice found myself moved to quote from The Hitch-hiker's Guide to the Galaxy. It's possible that absurdist philosophical satire is the most sane response to the tragedy that is the human condition.
We could do with some good satire on the assassination conspiracy theories. Oswald's motivations remain murky and I doubt we'll ever get to the bottom of them - heck, it's hard enough to explain Guiteau, and we know everything about him - but the actual physical facts of what happened are clearly established: three shots, one rifle, sixth floor, nobody else, nothing mysterious. Anybody who claims that there was anything impossible about this scenario - that Oswald couldn't have shot that fast, or that the bullet that hit both Kennedy and Connally would have had to turn in mid-air (the "magic bullet" theory), or that the movements of Kennedy's body mean he must have been shot from the front (the Oliver Stone theory)1 - is selling you a bill of goods. Here's a little something about that.
At this point I get to declare a personal interest in the matter. David W. Belin, one of the Warren Commission lawyer investigators who concluded that one bullet hit both victims, was a close family friend of ours. He'd known my mother since they were in college together, and he married her BFF (to use today's terminology).2 Here he is, with his characteristic bow tie, looking as I remember him from my childhood, on the job in the Texas School Depository building, with his colleague Howard Willens.
David wrote two books3 expounding the Warren Commission's conclusions about the facts of the assassination; he was particularly keen on pointing to the Tippett shooting as a key to Oswald's actions. The books are not easy reading, I'm afraid, and you might prefer Gerald Posner or Vincent Bugliosi for more lucid expositions. But David was as adamant as those authors that the Commission had come to the right conclusion. I remember once telling him about Greg Benford's novel Timescape, whose alternate-history plot depends on Oswald being Kennedy's sole assassin, as proof that not all of popular culture was against him. Friends who were at his deathbed say they knew he was gone when they'd whisper "Oswald didn't act alone" in his ear and not get a reaction.
So: yes, a lone assassin can kill a President. It doesn't require a world-spanning conspiracy or corrosive internal treachery. The world really is that tragic, and that preposterous. Time to break out the absurdist philosophical satire.
1. This would in any case point to the triple overpass rather than the grassy knoll, and that was originally considered, but there were too many people on the overpass and not enough murky shadows in photographs of it, so that was out.
2. B. and I still have on our coffee table the crystal bowl that David and his second wife (his first wife, my mother's friend, had died) sent us as a wedding gift. It's this bowl that keeps coming to my mind when I try to describe the shape of the auditorium in Disney Hall.
3. Yes, the third book is by him, too.