Promotion system is overheating

Tekst Yvonne van de Meent - WO&O Magazine - 31 augustus 2026 - 10 Minuten om te lezen

The growth of the scientific staff lags far behind the rapid increase in the PhD student population. Illustration: Peter van Dorst

The Young Academy wants to talk about "pro-chickens." These are professors who have so many PhD candidates under their wing that little comes of their supervision. Data research by the youth division of the KNAW shows that at Utrecht University, 15 percent of PhD candidates have a supervisor overseeing ten or more PhDs; at TU Eindhoven, this figure is as high as 30 percent. This has consequences. In 2020, research by the PhD Network Netherlands (PNN) already showed that one in five PhD candidates sees their daily supervisor at most once a month. They saw their supervisor even less frequently. This neglect leads to delays, dropouts, and mental health issues. That is why the Young Academy advocates for a limit on the number of PhD candidates a scientist may supervise: a "Limes PhDs."

The 'profkip' is a problem

The Young Academy makes no pronouncement on how high the bar should be set. To this end, they organized a panel discussion in the spring with representatives of PhD candidates, postdocs, assistant professors, and a full professor. The panelists did not doubt that the "professor chicken" exists and is a problem. However, setting a limit on the number of PhD candidates per professor is starting from the wrong side of the problem, argued PNN chair Martijn van der Meer. “We must ask ourselves how many PhD candidates we have room for, given the available supervision capacity.”  

Overheating

The number of PhD candidates has quadrupled over the past 25 years to over 12.000 FTE in 2024, according to an analysis published by the KNAW in February. This figure only includes PhDs employed by a university, which is the case for only 58 percent of PhD candidates. Last year, nearly 41.000 people were working on a dissertation, including external PhD candidates who support themselves, PhDs coming to the Netherlands on a scholarship from their home country to pursue a doctorate, and externally funded PhD candidates who are given the opportunity to conduct doctoral research by their employer (source: Een gezonde praktijk in het Nederlandse promotiestelsel, Universiteiten van Nederland).

You cannot let science continue to grow endlessly.

The growth of the scientific staff lags far behind the rapid increase in the PhD student population. The number of professors and senior lecturers increased by 62 percent in 25 years, and is therefore only one and a half times as large as in 1998. The system is overheating. “There are far more PhD students than the system can handle,” states Van der Meer. “The balance is lost, and there are only two ways to restore it: train fewer PhD students or hire more supervisors on permanent contracts. The latter costs an enormous amount of money and is also unrealistic. You cannot let science continue to grow indefinitely.” (Article continues below infographic)

Image: Ivo de Boer

The overheating is causing bottlenecks higher up in the organizational structure. “We are now training people for positions that do not exist,” states Christine Teelken, Professor of Organizational Change at the Vrije Universiteit. 70 percent of PhD candidates aspire to a scientific career, while a permanent position at the university is in prospect for only 30 percent, notes the professor, who conducts research into the well-being of young scientists.

Postdocs are the real scapegoat.

University research is increasingly funded on a project basis, and as a result, the number of PhD researchers with temporary contracts (postdocs) is growing. However, only 20 percent of these postdocs progress to a position as an assistant professor each year. This creates a waiting room full of PhD researchers with limited career prospects. “Postdocs are the real scapegoat,” believes PNN Chair Van der Meer. “The ratio between the number of postdocs and the number of permanent positions is completely out of whack. PhD graduates who want to continue in research end up in a postdoc prison.”

Mental well-being

It is an invisible group. “Postdoc is not a job category, so we don’t even know how many there are,” says Teelken. At the end of September, she will deliver the kick-off lecture of the Postdoc Appreciation Week who needs to put these researchers a bit more in the spotlight. That is sorely needed, because her research shows that their mental well-being is not doing well. “In 2019, we conducted a survey among 700 postdocs, and we repeated that last year with 600 participants. 40 percent were already struggling with mental health issues, and that is increasing on all fronts. It has mainly to do with the end of their appointments. It does not matter at which university or in which sector they work, gender, nationality; the decline is visible everywhere.”

Most postdocs consider their work to be very important in terms of content.

The uncertainty takes a heavy toll on their well-being. Postdocs postpone buying a house or having children. They feel constant pressure to perform and accept overtime so as not to jeopardize the chance of a permanent position. “But you shouldn’t be too dramatic about it,” says Teelken. “Most postdocs find their work substantively very important. They want to contribute to research that addresses societal issues. The temporary nature of their job makes it stressful.”

Unhealthy practices

The growth in the number of PhD candidates is facilitated by the PhD premium, states Rivke Jaffe, Professor of Urban Geography at the University of Amsterdam and a panel member at the debate on the 'profkip' in May. Annually, approximately 500 million of the 3,1 billion euro research budget is distributed based on the number of PhDs and design certificates. In 2025, a PhD yielded 96.199 euros, according to the Higher Education Finance Regulation (see box at the bottom of this article).

It is not only about becoming a good researcher in terms of content, but also a productive, healthy scientist.

“That bonus is a strong incentive to hire as many PhD candidates as possible,” states Jaffe. Which leads to the creation of ‘pro-chickens’. She herself supervises a maximum of six PhD candidates, always together with a co-supervisor. “That is my personal limit, which fits the holistic way in which I want to supervise PhD candidates. I find the pastoral dimension of PhD supervision, with attention to well-being, meaning, and a good work-life balance, just as important as the substantive guidance. A PhD trajectory is not only about becoming a good researcher in terms of content, but also a productive, healthy scientist.”  

Relatively without rights

The PhD premium leads to unhealthy practices, such as recruiting PhD candidates whom you do not have to employ because they bring a PhD grant from their home country or support themselves through side jobs. A quarter of PhD candidates fall into that category. This has been bothering Jaffe for years, not only because these PhD candidates are often in a precarious financial position, but also because they are relatively powerless without an employment contract. “PhD candidates are already vulnerable, but grant holders have no employment rights at all. If, for example, you come into conflict with your supervisor, you are often defenseless.”

Universities won't be cheering.

Rivke Jaffe would prefer to abolish the PhD premium. PNN chairman Martijn van der Meer is also a proponent of this. He would like to distribute research funding more based on supervision capacity. “You could distribute a portion of the 500 million currently spent on the PhD premium based on available supervision capacity. However, this does lead to significant redistribution effects that disproportionately benefit small universities with few PhD candidates and a relatively large number of professors and associate professors. That is why such a change must be introduced very gradually. It is currently risky for individual universities to appoint fewer PhD candidates when other universities are focusing on growth. Adjusting the distribution key can serve the collective interest of a good balance between the number of PhD candidates and available supervision time. Universities will not be cheering, but it would be very beneficial for the PhD candidates of the future.”

Dissatisfaction among a number of professors

Resistance is bound to come. In the spring of 2025, the Faculty of Science at the University of Amsterdam decided to stop hiring scholarship PhD candidates due to concerns about inequality in the workplace. This has led to dissatisfaction among a number of professors who argue that scholarship PhD candidates are necessary to build a research line. “To qualify for a research grant from science funder NWO, which allows you to hire a PhD candidate, you must first demonstrate extensive results in the form of publications,” states one of them in the university newspaper Folia. With fifteen Chinese scholarship PhD candidates, it has been possible to build up expertise that now makes it possible to obtain funding from NWO and companies. A fellow professor believes it is unfair to deny scholarship recipients the opportunity to pursue a PhD at a top university like the UvA—they sign for the grant themselves—and feels that his academic freedom is being curtailed by the faculty board.

You have no right to exploit someone else's labor, even if that person signed for it themselves.

“Absurd,” says Jaffe. “So these professors are saying: I have a right to the labor of a scholarship recipient, otherwise I cannot make a career in science. But you have no right to exploit someone else’s labor, not even if that person signed up for it themselves.” “Some professors view a PhD candidate merely as a publication supplier,” states Christine Teelken. “PhD candidates are not means of production,” believes Martijn van der Meer. “They are young people who deserve the best possible supervision. I think in terms of opportunities for the PhD candidate, not opportunities for the established scientist.”