Man hath no love greater than this: that he lay down his country for his frenemies

What can one possibly say about the murder of Jo Cox, an unassuming, hardworking Labour MP while she went about her job of listening and talking to her constituents, whether Labour voters or not? Her murderer is said to have had mental health problems and to have subscribed to fascist and racist publications and groups. The weight you give to both aspects of his life largely depends on a complex mix of preconceptions and biases. The hard-right newspapers such as the Sun and the Mail are keen to portray him as a 'mad loner' and downplay his politics; commentators on the left want to see it as an act of political terror.

My honest answer is that I don't and can't know the precise causes. Being a wet liberal I've always assumed that anyone who deliberately kills other than in self-defence, from a general to a drunk, is mentally ill in some way, but I'm also fully aware that of the enormous number of us who suffer from a range of mental illnesses only the tiniest fraction harm themselves, let alone others. I'm also very uncomfortable with the idea that because someone has an unspecified mental illness, we should deny them the agency of political views and the responsibility for their actions. If Thomas Mair was a racist bigot, we can't simply assume these are the products of his illness, however tempting and comforting that may be. It lets him off, but it also lets off those clamorous voices in the media which have grown ever more shrill and sinister: Donald Trump, the Daily Mail and the Express, Britain First and everyone who 'likes' their moronic Facebook posts, Nigel Farage and his friends, not forgetting those who cynically stoke up the fires of hatred out of opportunism rather than belief.

Only a few days ago we mourned the murder of fifty people for their sexuality in the United States, often accompanied here in Europe with a subtext of 'it couldn't happen here'. It probably couldn't, at least not on that scale thanks to the gun laws, but Jo Cox's murder should remind us that those instincts aren't exclusive to the USA. The managerial, technocratic politics of the End-of-History, which simply suppressed deep social fissures by proclaiming the triumph of the market has caused an atavistic resurgence of mostly hard-right, neofascist politics amongst those excluded from the magic political circle. I want a political system that's responsive, hard-fought, passionate and ready to have big arguments over the things that matter: it's not a gentlemen's game or the equivalent of management consulting, and when it seems like them, the people get angry. But nor do I want a politics that's played out on the street, a politics of shouting-down and beating-up or, as yesterday, of murdering our opponents.

What seems to have been lost is the notion of good faith: the idea that your opponents, however deluded, want the best for their chosen polity, whether that's a country or some other imagined community. Is anyone to blame for this? The easy answer of course is to say that we all are: that the corrosive cynicism of particular newspapers, commentators, culture and our own lazy assumptions have conspired to make politicians seem irreversibly cynical, lazy and corrupt. All of these things are true: Jo Cox, my own MP Rob Marris or any number of MPs from every party go to work every day dealing with things ranging from the horrors of the benefit system and what it does to their constituents, to painstaking, boring, line-by-line analysis of new legislation, to voting whether or not to bomb one country or hug another. It's hard, tedious and often lonely work.

However, politicians themselves must shoulder much of the blame. Those on the left and the right have worked hard to restrict politics as a practice to Westminster; they've abandoned much of their responsibilities to the market and ended up looking either like cheerleaders for the zero-hour, financialised economy and neoliberal, Clash of Civilisations hegemony, or as helpless onlookers of it. They've narrowed the boundaries of what can be reasonably discussed, from nuclear weapons to taxation to immigration (respectively my instincts are for abolition, raising and appreciating) and the type of people who are allowed to engage (it still very much helps if you're English, southern, white, male, privately-educated, went to Oxbridge, though women and homosexuals are gaining grudging acceptance). Nor does it help when credit is grabbed with both hands while blame is apportioned to others, currently the poor and the foreign.

The most breathtakingly cynical act of modern British politics recently was this European referendum. No major change in the UK's membership is proposed. A United States of Europe has not been declared, more's the pity. No earth-shaking constitutional changes are mooted. Rather the Prime Minister decided that the entire future of his country was a small price to pay for a temporary ceasefire within his own party and to fend off the advances of UKIP to his right. What's the old saying? 'There is no greater love, than that a man lay down his country for his frenemies'. The UK has for too long used the European Community/Union as a bogey-man or a scratching post: I'm frankly surprised that the rest of the EU isn't having a simultaneous referendum on throwing out the UK. As the debate has become less and less anchored in reality, xenophobic and atavistic tendencies have emerged. Whatever the contribution mental illness made to Thomas Mair's actions, the ruling classes bear an awful lot of responsibility for turning political engagement from a mass activity to a spectator sport, in which the teams are impossible to distinguish. It was inevitable that cynics would direct the unfocussed anger of the excluded into frightening channels, and that some tiny number of the dispossessed would emerge to do terrible things.

I will also say this: all politicians are guilty to some extent for behaving as though we shouldn't worry our little heads about politics. However, despite the public pressure not to 'politicise' the murder of a politician by a man shouting a political slogan, I believe that in particular, the Conservative Party's turn to neoliberalism has directly led to yesterday's murder. It turned away from 'One Nation' paternalistic conservatism and became the local branch of untrammelled, unregulated capitalism and financialisation. Anything the state does is now suspect. We have been trained to want the sale of our public services and to abandon our commitments to shelter the needy and those driven from their homes by war and terror. Our mental health services have been driven into the ground and those who – possibly including Thomas Mair – might benefit from therapy and care are left to fend for themselves, or offered mindfulness classes. Having encouraged us to see immigrants and refugees (or more accurately, poor, black immigrants and refugees) as freeloaders, bloodsuckers or diseases, often for electoral advantage, the Conservative Party cannot then disclaim responsibility for those even more extreme voices which simply follow their logic. The 'ratchet effect' of the 1980s claimed that a concerted effort to move political discourse to the right would force Labour to follow, and they were right: but the more space the Tories opened to the right, the more they had to occupy it themselves, however high-pitched the dog-whistle may be at times. If you want to see what a small-state, 'there is no such thing as society' polity looks like, you no longer have to move to Somalia. You can see it in microcosm when a man can become as ill and extreme as Thomas Mair without anyone noticing.

Who is more guilty than the politicians? We are. As a net-syndicalist I would say that as soon as we allowed politics to become a specialised activity practised by rich weirdos in hermetically-sealed spaces, we engineered our own disenfranchisement. They became the captives of their party whips, their donors and their increasingly unrepresentative parties. Look at the Conservatives now: a party essentially without a membership, and one which would far rather take millions from oligarchs to pay for Facebook campaigns than a party which actually wants to hear from millions of potential voters and members. Labour too has these tendencies: professional politicians in all parties think that the voters are basically selfish bigots to be appeased rather than the source of radical and progressive ideas who have a right to determine the nation's path. Donors are much more impressive, with their sharp suits, PPE degrees and private jets. But around the edges the extremist parties are peeling off the disillusioned with simple answers and easy solutions…

Politicians can't save us, but we can save the politicians. Nigel Farage and his friends aren't the cause: they're the symptom and the product of our age. If we encourage the best in our representatives and enforce a new mode of participatory political action – however uncouth and uncomfortable it may be at times – perhaps, just perhaps, we can reduce the chances of another Thomas Mair meeting another Jo Cox.