The pundits have cracked it: Jeremy Corbyn ran a better campaign (see, for example, here and here) and Theresa May’s was rubbish. This is generally explained in terms of a ‘galvanised youth vote’ or that Jeremy Corbyn is a ‘natural campaigner’.

But these things do not explain how Corbyn’s campaign was supposedly ‘better’. Vague statements about a ‘galvanised youth vote’ do not explain how the youth vote was so ‘galvanised’. At the same time, Theresa May’s campaign was extremely calculated and professional. She appeared early in the campaign in key seats so she would get into the local news, getting free election coverage. She fought marginal seats with surgical precision. By the usual campaigning logic, this was a brilliantly efficient strategy.

So what, precisely, was better about Jeremy Corbyn’s campaign? The answer lies in the basic assumptions made about voter behaviour.

One theory of how voters decide is that the decision is based entirely on a single issue, or, failing that, the impression that the public has of the party leader. Let’s dub this the Stupid Voter Theory. A campaign run under the Stupid Voter Theory seeks to control the public discourse by loudly and uniformly proclaiming a single message that is calculated to be discouragingly simple—say, that Theresa May is a strong and stable leader and Jeremy Corbyn is a terrorist sympathiser. This message does not have to be supported by facts or to be particularly well delivered; rational engagement is not its purpose. Rather, the message needs to be repeated. People will either start to believe it and vote Theresa May, or be so annoyed by it that they refuse to vote.

The method works particularly well in controlling losses in safe seats, as all but the most unquestioning party loyalists will vote and everyone else will be discouraged by the simplicity of the message. It also works wonders when the other party engages with it. If Labour had started to argue its case on the basis that Theresa May is not strong and stable, the election would have been decided on a comparison of party membership and core vote. The main electorate will not see a clear difference between the parties and rational swing voters will stay at home.

And so far, the Single Issue Strategy relying on the Stupid Voter Theory has led to moderate Conservative wins. In 2010, focusing on the economic crisis managed to swing the country from moderate Labour to a Tory-Liberal Democrat coalition. In 2015, focusing the election on having a ‘strong economy’ delivered a slim majority. In 2016, focusing the EU referendum on controlling immigration delivered a slim Leave victory. Brilliant, the pundits said.

But now, focusing the 2017 election on Brexit negotiations led to a lost majority and searing criticism of May’s campaign. True, she didn’t attend debates, but neither did David Cameron with Ed Miliband. The Stupid Voter Theory demands that debates are declined, as it is impossible to keep to a single issue in a debate without sounding like a robot (ask Marco Rubio). And true, the 2017 manifesto was vague and attempted to cut down on protected benefits. But this was also true in 2010 and 2015, when the cuts were aimed at hospitals, the disabled, the justice system and other equally controversial areas. The Stupid Voter Theory predicts that when the election is about one big issue, the party can include controversial proposals in its manifesto in order to get them passed in Parliament afterwards, because 1) nobody will notice them in an uninspiring manifesto, and 2) the Lords cannot vote down a manifesto pledge.

By the edicts of the Stupid Voter Theory, Theresa May was sailing tested waters and making her bed for the coming parliament. So what was different?

Jeremy Corbyn’s voter theory turned out to be more accurate. Corbyn has always realised that normal people are not stupid, it’s just that they have a lot on their plate. Corbyn’s model is therefore not that the general electorate is too stupid to understand the election if it is about more than one issue, but that they are rationally apathetic. Rational apathy, the idea that it would cost more in time and energy to read the parties manifestos than you stand to win from voting, will deliver the same predicted outcome if there is no clear difference between the two main parties. Most people don’t care which of the two bad choices wins, so they stay at home. The election is then won by the core vote and fanatics.

But this can change if the campaign concentrates on a range of issues that are clearly different from the other main party. This was Corbyn’s strategy. He unveiled a new policy nearly every day, and every policy was diametrically opposed to its Tory counterpart. Free university. Increased corporation tax. Increased tax on the wealthy. Renationalisation of infrastructure providers. No matter how hard May screamed Brexit, Corbyn kept bringing up the stark differences in their actual policies. (Challenge: name one Tory policy unveiled by May’s campaign).

Corbyn bet big on his fundamental belief that normal people are not stupid, but only rationally apathetic. By striking these contrasts with actual issues that benefit a large number of uncommitted voters—young people and people from diverse backgrounds, for instance—he sought to make it clear that it was no longer rational to be apathetic about voting.

And it clearly paid off. The turnout was moderately larger than in 2015, but also there was a 30 percent swing to Labour in the voting behaviour of 35 to 44-year-olds. These are people who are normally too busy with their jobs and mortgages, and so will vote on a simple issue or image if given no clear choice. This time the choice was clear, and that is why Corbyn’s campaign was better.

It remains to be seen whether the Rational Engagement Method will take root in the UK. But it looks like the Stupid Voter Theory is disproven, struck dead and buried. Of course, the analysts are blissfully unaware of the shift—it looks like they are currently blaming their miscalculations on pro-Corbyn memes and, you know, the internet. I for one wish to add my voice to those congratulating Corbyn—I am glad someone believes that normal people are not stupid. Let’s hope this belief is reflected in the actual policies of whatever government we end up with.

Lead photo by Matt Brown / Flickr

Aleksi Ollikainen is a College Lecturer in Law at Keble College, University of Oxford.