The Irish men’s rugby team is currently number one in the world. We might therefore expect its governing body, the Irish Rugby Football Union (IRFU), to be a proficient and effective organisation, capable of meeting its own aims while setting examples for others to follow.
Unfortunately, however, when it comes to cogency and competence, some parts of the IRFU appear to fall short of the standards set on the pitch.
Last week, the IRFU set fire to Irish Twitter with its new policy banning trans women from competing in the female category of contact rugby in Ireland. Women’s rugby will now be “limited to those whose sex was recorded as female at birth,” a restriction the IRFU says was based “solely” (and I emphasise “solely”, because I wouldn’t want to imply that the IRFU was in any way influenced by transphobic culture-war hysteria) on “new research related to safety.”
The policy has proven to be deeply unpopular, not least among the IRFU’s own star players:
Solidarity🏳️⚧️wholeheartedly stand with trans players youth families friends&allies. You deserve better, you deserve to be included in a sport that values inclusivity. Hope @IrishRugby reconsider excluding a minority group & maintain case basis so the sport we love truly is for all https://t.co/WIwdJcbSAG
— Ciara Cooney 🇺🇦 (@CooneyCiara) August 10, 2022
But notwithstanding its claims about being science-based, the IRFU’s new transgender policy is in fact logically muddled, and therefore scientifically dubious. It is also inconsistent, applying a different standard to women’s rugby than it does to the men’s game.
The biggest problem is that the IRFU’s restrictions on women’s rugby make little sense in their own terms. The new policy applies a one-size-fits-all solution to a problem it acknowledges to be nuanced, and as such is guilty of a logical error known as the ecological fallacy. In so doing, it arbitrarily marginalises and stigmatises trans women rugby players, and, by extension, trans people in general.
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The IRFU’s statement announcing its new policy doesn’t exactly exude scientific authority. It contextualises the issue with the following oddly phrased assertion:
Recent peer reviewed research provides evidence that there are physical differences between those people whose sex was assigned as male and those as female at birth, and advantages in strength, stamina and physique brought about by male puberty are significant and retained even after testosterone suppression.
I find the first part of that statement weird. It is strange that the IRFU feel a need to cite “peer reviewed research” to justify its point that “there are physical differences between those people whose sex was assigned as male and those as female at birth.”
Why bother? The practice of sex assignment is itself based on the assessment of “physical differences” among babies: if a baby has one type of anatomy, it is assigned the sex of ‘female’; if it has another type of anatomy, it is assigned ‘male’. We don’t need after-the-fact “peer reviewed research” to then provide “evidence” of these same physical differences. Sex assignment requires there to be physical differences to begin with. The proposition is therefore true by definition.
Of course, the key issue at stake here is that assigning sex to babies on the basis of observable physical characteristics is somewhat inexact. Many people have a gender identity that differs from the sex they were assigned at birth. In Ireland, this is recognised in law: Ireland is one of the countries that facilitates people to achieve full legal recognition of their preferred gender regardless of their assigned sex. The country’s Gender Recognition Act, passed in 2015, allows all people aged 18 and over to self-declare their own gender identity and to acquire a new birth certificate that reflects any change.
(And, for what it’s worth, literally millions of people around the world have sexual characteristics that defy binary gender conventions: around 1.7% of people are born with at least one intersex trait, about the same number as are born with ginger hair.)
But it is the second part of the statement that the IRFU uses to support its new policy. This is the wording that claims that trans women possess “advantages in strength, stamina and physique” that result from male puberty, and that these are “significant” enough to endanger the safety of other women players.
Therein lies the problem.
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So what then is the ecological fallacy? Well, here’s how Wikipedia puts it:
An ecological fallacy (also ecological inference fallacy or population fallacy) is a formal fallacy in the interpretation of statistical data that occurs when inferences about the nature of individuals are deduced from inferences about the group to which those individuals belong.
Ironically enough, the ecological fallacy comes in many diverse forms. But the key point is this: such a fallacy arises whenever we make assumptions about an individual person based on the group they belong to.
The IRFU commits this fallacy by applying its new policy to all trans women players, without evaluating any individual player’s own strength, stamina, or physique. So even if a particular trans woman player were to have less strength or stamina than her team-mates, that wouldn’t matter. According to the IRFU, she is to be excluded anyway. She is declared to be a danger to others not because of her size, but because she is trans.
The IRFU is seeking to justify a blanket ban on every single trans woman using research statistics that summarise trans women as a group.
And that is what is meant by the ecological fallacy.
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It is not as though the IRFU didn’t consider the idea of basing player eligibility on evaluating individual players on a case-by-case basis. For example, its new policy allows trans players to play on men’s teams so long as an individual “risk assessment” is carried out.
Such risk assessments will take account of the individual player’s own particular level of strength and physique. If it is established that nobody will be endangered by their participation, they will be allowed to play.
So, you see, according to IRFU, it can be done.
Unless you are a trans woman that is.
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What makes the policy even weirder is the fact that physical differentials don’t seem to matter as much in rugby as they do in other team sports. Rugby famously prides itself on being a “a game for all shapes and sizes.”
For example, have a look at these two opponents, Hong Kong’s Chong Ka Yan and Aotearoa Mata’u from New Zealand:
And let’s not forget this memorable photo of Ireland lock Maz Reilly standing next to Hong Kong scrum-half Chloe Mak:
Reilly and Mak were reputedly the tallest and shortest players at the 2017 World Cup. Mak was 1.5 m tall (4 ft 11 in) and weighed just 50 kg (7 st 12 lb), while Reilly was 1.94 m tall (6 ft 4.5 in) and weighed 85 kg (13 st 5 lb).
Reilly played for Ireland in several World Cups, retiring shortly after the 2017 tournament. The IRFU will surely be aware of her existence.
I wonder would it have insisted on one of those “risk assessments” if Ireland had been playing Hong Kong?
Or is it just trans women’s physiques that the IRFU are concerned about?
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And a final reminder that the IRFU went to all this trouble drafting its elaborate policy even though there are only two registered trans women rugby players in the whole of Ireland.
Or should I say there were just two trans women players in Ireland. Because of the IRFU’s dalliance with the ecological fallacy, there are now none.
“A game for all shapes and sizes,” supposedly. But just not if you are trans.

Brian Hughes is an academic psychologist and university professor in Galway, Ireland, specialising in stress, health, and the application of psychology to social issues. He writes widely on the psychology of empiricism and of empirically disputable claims, especially as they pertain to science, health, medicine, and politics.