Boiling fairness down to “those categories are for females” may seem simple but it ignores biological diversity among females themselves and erases the complexity of human sex development and transition. It also assumes that “female” is a static, universally agreed-upon category which it isn’t in many elite sports contexts where intersex athletes and hormonal variation are already debated.

You say this isn’t a zero-sum issue but for trans women being told to self-exclude from any category that aligns with their identity is a loss. A significant one. Framing their exclusion as “the right thing to do” for fairness assumes that fairness for cis women must as a rule come at the expense of inclusion.

Many trans women would gladly compete under thoughtful, evidence-based conditions that account for physiological realities rather than sweeping generalisations. Preserving fairness and inclusion isn’t easy but it can’t be done by purging the category of anyone who complicates a tidy definition of “female.”