The shooting of US Congresswoman Gabrielle Giffords and 23 other people is an appalling act. Rightly, the search for the cause of the outrage has begun.

Some say Sarah Palin and the Tea party are to blame. Some say lax gun laws are to blame. Some say the political culture of the US is to blame. No doubt the proximate causes are important. The political right in the US have been in a state of near hysteria since Obama became President. The merest hint of an alternative to unrestrained corporate rule at home and imperial chauvinism abroad induces a fervour normally only seen in counter-revolutionary movements facing an imminent socialist insurrection. Moreover, these populist right wing moods encompass a section of the working class.

There can be little doubt that whatever the individual motivations of the killer, these wider political factors have played a part. But there is a deeper question. Why is US politics like this? If we are to look at the fundamentals of US political culture there is one thing that is striking: the establishment political spectrum contains only pro-capitalist political parties. Its as if the only parties in the UK were the Tories and the Liberals. There is no Labour Party in the US and the unions are considerably weaker than they are here or in most other industrialised countries.

We’ve been told for a decade in this country that we should aspire to a ‘non-ideological’ politics. We should drop all the old dinosaur politics of class and just go with whatever policy works best. and if this is a market solution, which it nearly always turns out to be, then the left shouldn’t worry about embracing it.

But the trouble with taking ideology and class out of politics is that its a bit like taking principle out of politics. In fact its a bit like taking the politics out of politics. And when you take the politics out of politics what is left? Well, ambition, avarice, greed, corruption, egoism, personality politics, individual rivalry, that’s what’s left. If politicians don’t believe in anything but themselves, if they can’t locate themselves in a political tradition, with principles and solidarities…then its every Jack (and a few Jills) for themselves. This is what has increasingly happened in Britain and its been this way in the US at least since John Wilkes Booth shot President Abraham Lincoln.

A strong labour movement and Labour Party disciplines the whole political spectrum. It forces the left into more organised and serious politics and limits the individualism, syndicalism and autonomism that result from a lack of organised left politics. But it disciplines the right as well. It forces them to contend with the left in the political arena and raises the penalty bar for acts of extra-judicial violence. The US lack of a strong Labour movement has, from the Pinkertons to the KKK, allowed paramilitary forms of violence free rein. Small surprise if some individuals choose the same path.

And the more the political establishment fails, and Obama is failing just as surely as George Bush failed before him, the more political action flows into channels that are unpredictable. The anger of the right at the rise of Obama and the disappointment of the left at the decline of Obama is a dangerous moment. Class politics and the principle that goes with it would, more than any other single factor, improve the state of US politics.

In the 1880s Frederick Engels, no friend of reformist politics, argued that the creation of a Labour Party would be a step forward in the US. That is still true. A stronger far left and stronger unions as well would be even better.

Of course, not even a Labour Party and stronger unions would end the threat of right wing violence, as the assassination of Prime Minister Olof Palme in 1986 in social democratic Sweden illustrates. There are many other factors that can produce an assassin. But the persistent recurrence of political assassination in the US and the routine use of extra legal violence would be suppressed. For its abolition, socialism is necessary.