The strict mental illness narrative may be relevant to 'explaining' the Arizona assassination but in my experience of working with psychotic individuals -- including murderers and the like -- it is not very useful to divorce a persons' mental state from the broader social (and political) context. In this case, the linkage to contemporary politics is self evident as it was a political event with a history of some bitternes leading up to it.
If you compare this shooting with the slaughter managed by Martin Bryant in Australia the context is very different despite how psychotic both guys were at the time of the killing.
While people can brew a quite mad cocktail in their own heads it is difficult to imagine this event at a political rally occurring anywhere else outside the US except in a war zone.
And the US has to be seen as a war zone.
If a Islamist walks into a Baghdad market place and blows himself and 30 others up -- he is as mad/as pathological as this guy in Arizonia. If Sarah Palin calls for the assassination of Julian Assange (as she has) she's fuckin mad too...
At some point you have to look upon madness as an ideology embraced by both individuals and groups -- political currents and otherwise -- regardless of how much it is accepted as 'normal' discourse.And in the US 'normal' does no longer exist. Barbarism and psychosis are really one and the same head space.
It also seems to me that a lot of the response needs to face up to the fact that violent politics is as American as apple pie...and to defer too much to the individual case of mental illness argument merely lets the whole filthy capitalist mix off the hook.
Mental illness, even psychosis, is not a fast track sentence to murder .
After the Bryant massacre there was debate here on the left about gun ownership in response a massive recall of weaponry in private hands. Similarly Bryant was later sent to a mental institution ...and not executed as we had mass campaigns here against capital punishment way back in 1965/67.
The fortunately rare instance of serious political violence in Australia, -- the attempted assassination of the ALP leader Arthur Calwall in 1966 -- has the epilogue that its perpetrator Peter Kocan has just won Australia Council's Writer's Emeritus Award for poetry.
So in that sense the sort of step back we need to adopt has to be genuine and generous.
Like the argument in this post.
It has to be about adopting the moral high ground the exploiting the opportunity to foster reflection.