But more often in this country, assassins are just plain crazy. Maybe not legally insane — few qualify for that designation — but crazy in the vernacular sense of unhinged and obviously out of touch with reality. As disturbed individuals, their thinking is idiosyncratic and unpredictable, and their propensity for violence is sometimes telegraphed and noted ahead of time, although often formless and quite general. More importantly, what finally tips them over the edge into action can in many cases never be known, and appears almost arbitrary from the outside.

Who could have ever guessed, for example, the trajectory of John Hinckley, Reagan’s wannabee assassin whose bizarre obsession with Jodie Foster in the movie Taxi Driver led to the near-fatal shooting of the president? Loughner’s writings and YouTube videos so far indicate that his real motivations are likely to have been at least as idiosyncratic, bizarre, and incomprehensible as Hinckley’s, and probably more so. In fact, Loughner’s mind may be so disordered that he could end up making Hinckley look like a model of rationality in comparison.

Those who linked Loughner’s act to inflammatory Tea Party rhetoric didn’t want to wait to find out what they were dealing with. After all, political hay was to be made. If they had been a little more judicious, they would have discovered that this particular killer had been telegraphing his disordered and chaotic thinking for quite some time, thoroughly frightening quite a few people and institutions in the process, although all seemed powerless to stop the train wreck in the making.

But political points aside, what is the possible role of heated political rhetoric, be it on the left or the right, in motivating violent acts such as Loughner’s? It’s entirely unknown, but there’s no particular reason to believe such speech is especially influential. The first category of shooters — the cold-blooded and rational political assassins, out for political gain—are highly unlikely to be swayed by it. The second — the crazies, for want of a better term — can be motivated by nearly anything, and conventional political rhetoric tends to play only a small part in their confused and rambling diatribes.

Mere words are hardly enough to incite an act so extreme and so vicious, whatever the strength of one’s political convictions, and however great the anger at the opposition. Most people understand figures of speech, whether the mention of guns be Sarah Palin’s “reload” statements or the president’s campaign call for bringing guns to knife fights, and most homicidal lunatics are motivated by something far deeper, and far more perverse.