Jared Loughner has appeared in court in Tucson, Arizona, charged with several counts of murder and attempted murder following the weekend’s carnage at a political meeting.

Meanwhile, debate rages as to just how widely blame for the shootings should be extended.

There has been something of a backlash against the notion that the violence of political rhetoric on the American right, exemplified in particular by Sarah Palin and Fox news, should take a share of the responsibility. David Griffin, writing to Crikey yesterday, was representative when he said it was “like blaming Marilyn Manson for the Columbine massacre.” My colleague Richard Farmer draws attention to similar arguments in Der Spiegel.

But I think much of the commentary rests on a misunderstanding of how causation works. Causal processes are not hard facts; they’re not “things” that we discover out in the world. What actually exists is the events themselves; causation is an interpretations that we impose on those events, reflecting human purposes and interests as well as the underlying physical reality.

So while most of the time the concept of causation works perfectly well and gives us nice clear answers, it’s always liable to break down at the margins and display its fuzzy edges. In a case like this we can find ourselves asking questions that just can’t be answered, even in principle.

All the more important, then, to be clear about what we’re not looking for. No one is suggesting that Palin or anyone like her intended something such as this to happen, or is anything less than sincere in her condemnation of the murders. Even her worst enemies (such as Andrew Sullivan have been crystal clear about that.

Nor does anyone think it likely that Loughner will turn out to have been himself a tea partier or to be directly associated with any overtly political group. There’s been a suggestion that some of his writings show an affinity with the ideas of conspiracy theorist David Miller, but Miller himself — who believes that punctuating his name correctly makes him immune from taxation — is so far outside the mainstream that even if true this would not add much to the picture.

The sort of causation involved — if “causation” is the right word — is much more indirect. What we do is influenced by the atmosphere around us; we pick up on the tone and direction of what is said by the thousands of people around us, and on what is treated as normal or otherwise, in ways that could never be tracked precisely.

With that background, there is surely nothing crazy about the suggestion that a political shooting is in part — in addition, that is, to the shooter’s own personal demons — a result of the increasingly violent nature of political discourse. In Paul Krugman’s words, “there’s a big difference between bad manners and calls, explicit or implicit, for violence; insults aren’t the same as incitement.”

If, most improbably, it could be shown that Loughner had never watched Fox news and never heard of Sarah Palin, then we could have some confidence that there was no causal relationship involved. Even then, however, it would still be true that turning down the heat on violent rhetoric would be a good thing.

Whether or not we blame the voices of hate for what happened in Tucson, we can certainly blame them for making exactly that sort of thing more likely.