Kristian Niemietz is Head of Political Economy at the Institute of Economic Affairs.

“Hey guys, wanna feel old? I’m 40. You’re welcome”, Macaulay Culkin – the actor who is most famous for having played the role of Kevin McCallister in the Christmas classics Home Alone (1990) and Home Alone 2 (1992) – tweeted last summer. His tweet received over half a million retweets, and over three million likes, presumably because it created a nice bit of cognitive dissonance in the minds of millions of people.

If, like me, you have been watching the movies every Christmas for as long as you can remember – something in your mind will militate against picturing “Kevin” as a middle-aged man. It just does not compute. The more rational part of your brain will be quite capable of working out that 2020 minus 1980 equals 40, but that will not stop the more intuitive part of your brain from screaming: No, Kevin is a boy! He cannot be 40! 

Something a bit like that has happened, collectively, to the Millennial generation as a whole, albeit more as a result of a semantic confusion. If Google Books Ngram Viewer is anything to go by, the word “Millennials” entered the English language at the end of the 1990s, and then began to take off in the mid-2000s. At some point, probably soon after, “Millennials” simply became a synonym for “very young people”.

At the time, this was, of course, entirely correct. Millennials are people who were born between the early 1980s and the mid-to-late 1990s, which means that when the term entered popular usage, the oldest Millennials were in their mid-20s, and the youngest ones were still children.

However, linguistic conventions, once established, develop inertia, and become hard to shift, even as the reality they try to describe changes. Today, the term “Millennial” still has the same connotations it had one and a half decades ago, but the people it describes have not stayed as young as they were then. Hey guys, wanna feel old? Some Millennials are 40. You’re welcome.

This is not just a matter of linguistic pedantry. The fact that we still use “Millennials” and “young people” synonymously seems to be causing some real confusion. As I show in my recent IEA report Left Turn Ahead?, over the past five years or so, there have been a flurry of surveys showing a rising popularity of socialist ideas among Millennials (as well as, increasingly, Generation Z). A generation, if not two generations, has turned against capitalism.

If you hold the uncool, unfashionable “OK Boomer” opinion that capitalism is a lot better than its reputation, this should be a cause for concern for you. And yet, oddly, people on the pro-capitalist side of the argument have not shown much interest in the rise of “Millennial Socialism”.

They usually brush it aside with phrases such as “The young have always gone through a socialist phase”, “They will grow out of it”, “It’s easy to be a socialist as long as mummy and daddy pay your bills”, “Wait until they start working”, “Wait until they start paying tax”, “Wait until they enter the real world”, and so on.

People who dismiss the rise of Millennial Socialism in this way seem to be picturing somebody in their late teens or early twenties. Because Millennials are 20 years old, and Kevin is a boy, right?

But what the survey data really shows is that socialist ideas are still just as popular among people in their early 40s as they are among people in their late teens. This does not mean that those views are set in stone, and that the Millennial generation is a lost cause for supporters of the market economy.

But it does mean that Millennial Socialism cannot be dismissed as an expression of youthful naivete, a lack of real-world experience, or as a passing phase. Rather, among politically engaged Millennials, socialist opinions have become default opinions. Default positions can be changed, but only with active efforts. They do not change on their own.

At the moment, Baby Boomers and the preceding generation – generations which tend to be more sceptical of socialist ideas – still outnumber Millennials and adult members of Generation Z. But already over the course of this decade, that lead is going to disappear, and turn into a solid Zoomer-Millennial majority.

If I were Jeremy Corbyn, I would try my luck again in a few years’ time. If demographics is destiny, the future belongs to the socialists.