Vasterman: The Battle Between Sex and Gender
Peter Vasterman examines the bill for a new transgender law, the works of Kathleen Stock, Debra Soh and Helen Joyce, and the consequences of self-identification for women, science and the consulting room.
A Bill That Removes Biology
The bill amending the Transgender Act, which Vasterman wrote about in 2021, sought to allow the sex on a birth certificate to be changed based solely on a declaration. No expert assessment, no physical process. The bill was withdrawn in 2025; the Transgender Act of 2014 still requires an expert assessment. Vasterman sums up the essence dryly: "the only thing that matters under the new law is the 'experienced gender identity'". This would have detached the legal concept of sex from the biological one. It seemed like an administrative adjustment, but it represented a shift in what a woman or a man is in legal terms — from an observable characteristic to an inner feeling.
Three Philosophers Who Dissect the Ideology
Vasterman discusses three books: Material Girls by philosopher Kathleen Stock, The End of Gender by sexologist Debra Soh and Trans by journalist Helen Joyce. None of these authors denies that trans people deserve rights. What they dispute is the claim that an inner "gender identity" literally makes someone a woman or a man. Their work restores the distinction: sex is biological, gender is a set of social expectations, and self-identification changes neither. It is precisely this distinction that the Dutch bill erased.
Biology Matters — Including in Behaviour
The claim that gender differences are purely social constructs does not hold up in light of what animal and human research show. Foetal testosterone influences play behaviour, career preferences and interests. Soh analyses this extensively: the image of a "blank slate" on which culture alone writes does not stand up. Vasterman draws the logical conclusion: if sex produces biological differences in behaviour, the claim that "being a woman" is a purely social label is an ideological claim, not a scientific one.
A New Group of Girls Changes the Picture
Since 2012, huge numbers of teenage girls have presented at gender clinics without any history of childhood gender distress. On TikTok, Tumblr or in groups of friends, they suddenly discover that they are "actually a boy". This profile does not match the classic patient for whom the Dutch Protocol was written. The background to that Dutch treatment model is described elsewhere on this site. Vasterman sees here where Lisa Littman's hypothesis of social contagion gains empirical traction. The claim that dysphoria is always innate and always persists breaks down when confronted with this cohort.
Women’s Spaces and Sport Under Pressure
Once "woman" is redefined as "anyone who feels that way", the legal basis for female-specific facilities evaporates. Vasterman lists them: "It is not only about separate toilets, but also changing rooms, prisons, women's shelters and, of course, sport." In each of these domains, safety or fairness considerations exist that are explicitly based on biological sex. In her book, Joyce documents how British and American policies were changed over the course of a few years without public debate, resulting in concrete harmful incidents.
Science Gagged
The taboo on criticism has a suffocating effect on research. Stock was driven out by students and colleagues at her university. Such ostracism of dissenters is described as a mechanism on gendersekte.nl. Researchers who raise questions about puberty blockers, social contagion or comorbidity are labelled "transphobic". Vasterman writes that "many subjects have been declared taboo". The irony is that in virtually every medical field where there is so much uncertainty, science demands more research. Here, the question itself is criminalised.
Diagnostics Based on Self-Reporting
Vasterman points to a fundamental diagnostic problem: "Not only is diagnosing gender dysphoria problematic, because everything depends on what the person says themselves." There is no objective test, no biomarker, no scan. The diagnosis is whatever the patient reports — preferably in a story that aligns with the existing criteria. For adults, this may be an acceptable trade-off. For thirteen-year-old girls, often with autism, an eating disorder or depression, it opens the door to irreversible interventions based on self-reporting.
Detransitioners as a Blind Spot
A growing group of former patients — especially young women who received testosterone and mastectomies during their teenage years — are speaking publicly about regret and lasting physical harm. Trans activists respond with denial or minimisation. Vasterman describes this as a stifling effect "that not only harms the social position of women, but also has a stifling effect on science". Those who silence these voices exclude precisely the cohort that has the most to say about treatment outcomes.
What Is at Stake
Vasterman offers a synthesis: the battle is not about whether trans people exist or deserve rights. They do. The battle is about whether a felt label overrides the actual biology of a body — legally, medically, athletically and linguistically. The three books he discusses answer no, on clear scientific and philosophical grounds. The Dutch bill answered yes, without the debate ever being properly conducted. The difference between these two positions will shape every policy discussion about changing rooms, clinics, sport and speaking spaces in the years to come.