Labour leadership election: Why are Jeremy Corbyn supporters so fond of dishing out insults?

The verbal abuse directed at insufficiently left-wing members of the Labour party during the leadership contest is both comic and sinister. Comic because there is something unserious about a person making a judgement about you (who they don't know) based on the fact that you don't plan to vote for Jeremy Corbyn. Sinister because the abuse has brought to the surface a simmering undercurrent of anti-Semitism on the left (hurling the word Zionism around every two minutes is demonstrative of several things, of which concern for the Palestinians is not one).

That's for another article and another time, however; today I want to focus on the more run-of-the-mill abuse that seems to be an increasingly common feature of left-wing politics. The abuse of one's political opponents is not confined to the left. However, on the right it tends to be the preserve of the far-right – i.e. to the sorts of people for whom multiculturalism is a project dreamed up in dark cellars by freemasons.

As a test of this theory, start an argument with a Tory and see if you can coax them into likening you to some malevolent insect or disease. It almost certainly won't happen. The typical conservative may be horrifyingly wrong about almost everything, but they probably won't insult you about it. So why is it an increasingly common feature of the left? The following are, in my experience, the principle reasons:

The gap between the far-left and the centre-left is permeable

There is a lack of separation in progressive politics between the respectable left and the communist left. Or put another way, the entire political space on the left is permeable, and social democrats view communists as in some vague sense 'on the same side' as themselves (though the feeling rarely extends the other way). Consider the following: no Tory MP will march through Trafalgar Square alongside far-right thugs holding aloft portraits of the Fuhrer; yet Jeremy Corbyn can do the same with communists and portraits of Stalin.

This lack of a 'wall' between the hard-left and soft-left ensures that much of the bile on the fringes seeps into the mainstream – and there is a good deal of bile on the fringes. As with the far-right, many individuals on the far-left are attracted to politics because they see the 'movement' as a substitute for a world in which they feel alienated. As a member of a small conspiratorial group with a theory about everything, the activist and his comrades can invert things and project their own inadequacies on to the world: we do not have a problem; it is everyone else. Living human beings (who are obviously the victims of false consciousness) are also sometimes replaced by vague notions of 'humanity'; in extreme cases non-believers become non-people who can be treated with brutality and indifference (or called 'scum' on Twitter).

Some of the vitriol comes from a good (if misguided) place

Self-righteous people can often grant themselves licence to behave appallingly – they are after all on the right side of 'history', whereas those they are assailing are holding progress back. When an otherwise civilised person unleashes a volley of abuse at someone they have never met, they probably view it in the context of a struggle against a greater barbarism. You can't make a borscht without cutting up beets, or something like that.

Taken to its extreme, certain causes are attractive precisely because they provide an excuse for behaving badly – they give the believer the 'right to dishonour', as Dostoevsky puts it in Demons, his treatise on nihilism.

The left is weak

Socialist politics is in the doldrums. The left is not simply suffering an emotional spasm on the back of May's election defeat; it is still coming to terms with the rise of Ronald Reagan, Margaret Thatcher and the fall of the Berlin Wall. Few on the left have any idea what a viable socialist economy would look like in 2015 (Venezuela provides an example of what it should not look like); meanwhile the only form of social democracy that appears capable of coming within a sniff of power is of the anaemic New Labour variety.

Dogmatism on the left is a foil for feelings of impotence and insecurity against this bleak backdrop. The constant search for 'Red Tories' is the civilised equivalent of the religious fanatics who hunt for heretics when their own faith is wobbling.

There is a widespread misunderstanding about Conservatives

The Marxist canon assumes that all politically conscious people are motivated by economic self-interest. Or to put it more crudely, that Tories are Tories for no other reason than a desire to hang on to their money. Often this is true: who hasn't met the student radical in the Che Guevara t-shirt who suddenly wants to cut taxes when the well-paid job in the city beckons?

But other motivations cut across purely economic considerations. Wealthy people are not predisposed to villainy; they do not leap out of bed in the morning to invigorating thoughts of children wallowing in mud and rags. Many politically active Conservatives are also 'trying to make the world a better place' – their proposed solutions simply differ from those articulated by the left.

But this is a point rarely grasped. As things stand, admitting that you vote Conservative is comparable to saying you enjoy bludgeoning babies to death with a pickaxe. Tories are evil, scum, non-people etc – and 'Red Tories' are traitors in the left's midst.

This is not an attempt to explain every variant of abuse emanating from the left. Nor do most leftists direct personal abuse at people with whom they disagree. But a strangely high number do; the phenomenon of 'shy Tories' is surely testament to the fear many people have of admitting to holding the 'wrong' opinion.

In a democratic country you needn't be a Conservative to find it all rather shameful.

James Bloodworth is editor of Left Foot Forward. You can follow James @J_Bloodworth and his blog @LeftFootFwd.