Why Do the Bells Toll? : How to Understand and Address the Disputes Around Evidence in Support of the Use of Puberty Blockers for Young People with Gender Incongruence/Dysphoria.

Disputes around puberty blockers and gender-affirming hormones for transgender and gender-diverse youth (TGDY) are often framed as disputes around evidence. Recent reviews, including NICE (2020) and the Cass Review (2024), have characterized the supporting evidence as "remarkably weak," prompting calls for further research and regulatory restrictions. This paper explains why producing more or "better" data is unlikely to resolve these disputes. Drawing on Kuhn's account of paradigms and the theory-ladenness of observation, I show that disagreements in paediatric gender medicine reflect not merely gaps in knowledge but deeper metaphysical and normative divergences about sex, gender, health, human development, and the legitimate goals of medical intervention. What counts as evidence, which outcomes matter, and how findings are interpreted depend on competing conceptual frameworks and value commitments. In this light, the proliferation of studies and continuing dissatisfaction with their results are symptomatic of a paradigmatic crisis, rather than a simple evidentiary deficit. This paper does not deny in any way the value of empirical research. It rather points out that appeals to "evidence" risk obscuring the normative dimensions of clinical judgment. Resolution will depend less on the accumulation of data than on explicit ethical deliberation, clinical experience, and engagement with the worldviews that shape what is taken to be meaningful knowledge. This paper first explains why repeated calls for stronger evidence persist despite a substantial empirical literature, by showing that these calls rest on divergent standards of evidential relevance. Second, it shows that the dispute is paradigmatic and as such cannot be adjudicated by data alone. This paper resolves an apparent impasse in the literature and clarifies the limits of data-driven resolution, with implications for clinical guideline development and evidence review processes.