UK 24 August 2015 What's the cause of Corbynmania? The group dynamics of a leadership contest were always going to incline towards an extreme conclusion of one kind or another, explains Steve van Riel. Getty Images Sign UpGet the New Statesman's Morning Call email. Sign-up Political metaphor is full of gathering storms and unstoppable tides. And yet, politics involves largely the same people, voting on largely the same issues, year-in, year-out. Whether it’s the Blairite glory days of Cool Britannia, the brief outbreak of Cleggmania in 2010 or the apparent surge behind Jeremy Corbyn today, it’s easier to talk zeitgeists and national trends than to break it down to the very specific: who has changed their minds and why? The easiest specific answer is always the arrival of new people. Entryism’s less dramatic cousin, exitism, probably also plays a role. And perhaps that’s all that is going on with the Labour Party: some loud, new people joining, others quietly leaving. Yet this fits suspiciously neatly into another fallacy: assuming that people’s views are inherent to them rather than influenced by the context in which they find themselves. Cass Sunstein, who is best known as one of the co-authors of the behavioural economics bestseller “Nudge”, wrote another book a few years ago called “Going to Extremes” focussed on one recurring finding in psychological research: that groups, of any kind, tend to become more hardline, the more they debate an issue. Business students and chess players become bolder after discussing with others while more cautious groups become even more cautious. Juries award higher awards after deliberation than they would have done individually. The phenomena occurs whether the question is, for example, race, feminism or American foreign policy. So it shouldn’t be a shock that when Labour Party members gather online or offline to choose a new leader, they become less moderate than they were beforehand. In other circumstances, with a different discussion, party members might have moved from a mild concern about winning elections to the kind of obsessional devotion to winning that Philip Gould described in the Labour Party of 1997. In this case, however, the indications are that the psychologically predictable shift to less compromising positions has manifested itself as a shift towards the Campaign Group vision of the left. If I show you photos of some short people, you’ll overestimate how tall you are. If I start spending more time with leftwing basketball stars, I may start to believe I’m centrist and short, even if I’m still relatively leftwing and tall compared to the rest of the population. I’m unlikely to hear many anti-basketball arguments and if any of us are a ambivalent about basketball, we are less likely to voice that feeling than the most confidently committed fans. Economists think of market bubbles coming from informational cascades: if most people I know tell me that house prices are going to rise, eventually it may become rational for me to suppress any private doubts I have. The same motor powers group polarisation. Why this particular shift? One feature of attitude shifts that Sunstein and others have identified is that the situation can sometimes give one side a “rhetorical asymmetry” that predicts which direction the shift will take. For example, law students found it easier to argue for a higher fine than a lower fine for a corporation, even before they knew the details of a case. I suspect the same has now happened to the left/right debate in the Labour Party: after five years of a leader who often gave the impression that he thought those to his right were morally weaker than he was, it isn’t surprising that people now find it easier to take an ever-more-left position. That’s before we start actually denouncing each other. Some of this has come from the top but it seems to be a particular favourite of political Twitter in the UK. And if rudeness can spread like a virus through a population, then perhaps so can the tendency to denounce other members of your political party. Such denunciations may not merely silence the doubters, they may give believers a false impression that there are only a few doubters. Online discussion has been found to create a strong sense of group membership, and so is especially susceptible to polarisation, because it allows people to emphasise what they share (through, say, a campaign Twibbon) and underplays the many differences between, for example, the middle aged, male Twibbon-bearer in the North and their young, Black, female, Southern comrade. In the case of the Labour Party, there may have been one final accelerant. The group polarisation effect sometimes appears to work more strongly with people who are closer to the poles of an argument. I suspect it may be that it is harder for group discussion to turn a Brownite into a passionate member of the Milifandom than it is to turn a Milifan into a Corbynista. There’s nothing especially leftwing about this or indeed a need for it to be expressed on a left/right spectrum. Whether any particular shift in attitudes is good or bad is entirely up to you. But when something starts to spiral into a self-sustaining dynamic, towards ever-greater certainty, it should set alarm bells ringing. Sunstein reassures his readers that there is a break to how far a group can veer off any one direction. This is because “political organizations are interested in attracting members and in achieving their goals and this has significant limiting effects on potential movements… [in the same way as companies] will be punished if consumers do not like their products.” The big question posed by Corbynism isn’t whether he can win the leadership, it’s whether the Corbynistas can remove that brake completely. › Proms 2015: There's nothing better than late night Bach Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!