Sweden’s youngest PhD has had a busy few weeks. Since completing his doctorate – becoming the youngest person in the country to do so – he has done plenty of media interviews about his work, appearing in over 50 publications.

“It’s been great, because you don’t normally see philosophy in the news!” he tells us when we meet in his office at Stockholm University. “And not many people have heard of the philosophy of mathematics.”

Summing up his thesis, Buijsman explains: “I'm looking at how we learn maths – and trying to understand what it is. Is maths about anything real, or is it just something we’ve been making up for 3000 years?”

Buijsman, originally from Leiden in the Netherlands, completed his work in just one and a half years (after finishing his Master's aged 18).

“The main reason was that I had lots of supervision from two very good professors; they were one of the reasons I chose to come to Stockholm. I wrote a chapter of my thesis every two weeks, then they’d tell me for three hours straight every single thing that was wrong with it. I’d write something new and then two weeks later we would repeat the process!”

The philosopher credits Sweden's more informal working culture with making this possible. Compared with the Netherlands, he says “getting help is easier here, people are very approachable. So it's much easier to go to a professor and talk about what you’re interested in or struggling with”.

Stefan meets the Dutch Ambassador after completing his PhD. Photo: Anna-Karin Landin

But what makes his speedy completion of the doctorate even more impressive is the fact that he didn't need to pull any all-nighters in the library to achieve it – quite the opposite.

“I try to limit very strictly how much I work,” says Buijsman. “In my experience, if I work more than 35 to 40 hours per week, it’s too much. Especially with work that’s mentally demanding, your brain needs long breaks so you have the energy to be creative.”

This relaxed – and very Swedish – approach to working hours has also given the academic plenty of time to get to know his new country and to meet people.

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He hasn't found that his age has been a barrier to socializing with fellow PhD's.

“I skipped my first class at the age of four, I have always been around older people so I don’t really know anything else. For the first two weeks, it’s a bit strange for everyone else, but then they get used to it – I’m doing the same kind of work so people forget that I'm 20.”

Despite being close to a decade younger than the average PhD in Sweden, Buijsman wasn’t nervous about his defence – the public debate with professors which marks the conclusion of the degree.

“It was a lot of fun!” he laughs. “One of the professors is designated as your 'opponent', and they question you on your ideas. We spent half the time just discussing my ideas and getting excited about what to do next.”

Indeed, Buijsman's work could prove very useful for teachers, psychologists, and everyone who has ever complained that they just don't 'get' maths.

He explains that the field of philosophy of maths has for a long time been dominated by two groups: “One group believes numbers are things which really exist, and that when we do mathematics, we discover things about them. The other believes they do not exist, and we just make everything up.”

Photo: Anna-Karin Landin

Buijsman's research looked at how non-experts use maths in everyday life, for example when shopping – and discovered that “absolutely none” of the theories philosophers had come up with can be applied to how ordinary people use maths.

“This means some people are making it all more complicated than it needs to be – and we don't have a good understanding of how people learn maths.”

Having reached this conclusion in his PhD, Buijsman's post-doctorate studies – which he started “pretty much immediately” after finishing celebrating – will look at how people do use maths in real life.

“What’s next is the interesting and useful bit,” he says, adding that he hopes his work will prove useful for teachers and psychologists, as well as students.

“It could be very helpful. Of course, telling people some philosophical story of what numbers are isn't very useful, but right now we don't have a story that everyone agrees on anyway. Understanding how we learn maths may help give us more effective teaching methods.”

The 20-year-old received offers from several universities when he was applying to do his PhD, and chose Stockholm not only because he was keen to work abroad – “getting to know a new culture is nice even though Sweden and the Netherlands are fairly similar!” – but also because Sweden is one of the few countries with funding for his field.

He hopes that other countries will start taking a leaf out of Stockholm’s book when it comes to research funding.

“In the Netherlands and other countries, the rationale for cutting funding to the humanities is that it isn’t producing anything economically valuable straight away.”

“Swedes have much more long-term thinking – they recognize that this work could be very beneficial to society, it just doesn’t produce something that you can sell one year after the research has finished. The system is also much more flexible so you there's a lot of opportunity to do whatever you are passionate about.”

As for whether he will stay in Scandinavia once his three-year post-doctoral studies have finished, he isn't sure. “It depends on job opportunities, which are always a very uncertain thing in the academic world,” says Buijsman.

“But I certainly wouldn’t mind if it became long term!”