The term “gender identity” is often treated in public debate as an established, measurable fact: someone has it, feels it, and the rest of the world must acknowledge it. In his new book Gender Identity: The Career of a Category (Polity, 2026), American sociologist Rogers Brubaker takes a different approach. He does not ask what gender identity really is, but what the category does: how it functions in laws, clinics, schools, and social movements. According to reviewers, this makes the book the most useful overview to date of what is happening in the “gender world.”

A Social Category, Not an Inner Fact

Brubaker’s central move is methodological: he treats gender identity not as a thing in itself, but as a social category—much like sex, sexual orientation, race, ethnicity, nation, or religion. Such categories operate in several ways at once. They are performative: individuals and institutions take action on the basis of them. They are productive: the category generates not only labels, but also types of people who begin to act in accordance with them. And they are interactive: engagement with the category changes its meaning, or even gives rise to new categories. Through this lens, Brubaker does not need to take a position on what gender identity metaphysically “is”—he simply describes what happens under that banner.

The Problem with the Word “Gender”

According to Brubaker, much of the confusion lies in the ambiguity of the word “gender” itself. It can refer to sex in the conventional sense (male/female), to the social structure and culture surrounding sex, or to gender identity as an inner feeling supposedly related to gender. Philosophers such as Kathleen Stock (Material Girls) and Alex Byrne (Trouble with Gender) attempted to define precisely what this inner feeling means, but ran into a second problem: is that feeling an innate “true sex” that can differ from one’s sex at birth, or rather a subjective self-image with a cultural mode of expression? Brubaker himself cites the “strong” and “weak” definitions circulating in the field: the strong definition—which emerged alongside the medicalization of transsexuality in the mid-twentieth century—sees gender identity as a fundamental and unchangeable identification with one of the two sexes; the weaker, more recent definition makes it an individual experience of gender that may or may not be linked to the binary sex classification.

Why the Sociological Approach Helps

The advantage of Brubaker’s approach is that he does not need to settle this definitional dispute in order to say something meaningful. By examining what concretely happens under the heading of “gender identity”—which laws are passed, which clinical protocols emerge, and which social movements take shape—he can map the dynamics without first having to adopt a metaphysical position on the nature of the phenomenon itself. This is a useful step in a debate that often stalls because supporters and opponents talk past one another about what the word is supposed to mean.

Significance for the Broader Debate

For those following the debate around gender care and policy, this book is relevant because it offers a third path alongside the two polarized camps: one camp that treats gender identity as an unquestionable inner fact, and another that rejects the concept altogether. Brubaker shows that it is possible to seriously analyze the social operation of a category—including the institutions, laws, and clinical practices built around it—without having to answer the question of the “true nature” of gender identity. This makes the book essential reading for anyone seeking to engage in the debate more precisely, regardless of their own position.