Where Sex and Gender Part Company
For centuries, the words “sex” and “gender” were used interchangeably in the English language. That usage changed after World War II, when sexologists, psychologists, psychiatrists, social scientists, and feminists began to distinguish— usefully and provocatively— between sex and gender. In recent years, however, that postwar distinction has become a casualty of the culture wars— and both gender activists and social conservatives are in part to blame.1 When political opponents use the same words to mean different things, there’s bound to be conflict and confusion.
“One is not born, but rather becomes, a woman.” This well-known aphorism from Simone de Beauvoir’s The Second Sex (1949) encapsulates the postwar sex/gender distinction. In everyday language, female and woman mean virtually the same thing, as do male and man. But in the language of second-wave feminism, female is to sex as woman is to gender: being born female is not the same thing as becoming a woman.
The psychiatrist Robert J. Stoller crystallized the postwar consensus on sex and gender in 1968 in his lucidly titled book Sex and Gender: The Development of Masculinity and Femininity. Stoller reserved the word “sex” for the male/female distinction, a distinction based on reproductive functions. While intersex conditions or differences in sex development (DSDs) may lie outside the male/female binary, most individuals fall “under one of [the] two separate bell curves”: male or female. In 99.98% of all cases, sex can be determined by observable biological traits: “chromosomes, external genitalia, internal genitalia (e.g., uterus, prostate), gonads, hormonal states, and secondary sex characteristics.”2
Gender, on the other hand, was assigned a different meaning. It referred to something more abstract, namely (1) the recognition or self-awareness that one is male or female and (2) one’s own sense of “masculinity or femininity.” If sex was a relatively straightforward function of biology, gender was culturally, psychologically, and socially constructed. Men might display conventionally “masculine” qualities and women conventionally “feminine” qualities, but there were “mixtures of both” to be found in everyone.
Gender has often been used as a polite-sounding euphemism for biological sex, but scrupulous writers and speakers— especially those schooled in postwar feminism— used to speak a common language regarding sex and gender.3 More recently, however, there has been a decided preference for “gender” and its seemingly endless possibilities over the predictable binaries implied by “sex.” The result has been a rapid proliferation of the gender concept, often to the neglect of biological “sex.”
Take, for example, the strange misnomer now used for “all-gender” bathrooms. Historically, schools and other public places have separated male and female restrooms. These are segregated on the basis of sex, not gender: they are examples of what lawyers and academics call “sex-segregated” spaces. In the modern era, sex-segregated bathrooms have been justified as a form of protection for women in public— a way to minimize unwanted male attention and male sexual aggression. It’s the sex (not gender) binary that explains the absence of urinals in female restrooms and the absence of sanitary product dispensers in male restrooms.
“Unisex” or “mixed-sex” public toilets are designed for use by both sexes, including trans men and trans women, and by those who identify outside the gender binary. But gender activists do not like the term “unisex” because it calls attention to the binary nature of “sex.” Activists argue that the very existence of intersex variations— the fact that a small number of people are born with bodies that do not fit the categories male/female— calls into question the legitimacy of the male/female distinction.4
The gender concept suggests fluidity and choice. Language such as “all-gender” and “gender-free” seems to transcend the male/female binary by ignoring it altogether. Exchanging sex for gender opens up political opportunities and opportunities for self-expression, but it also leads to some predictable confusion. School leaders might be forgiven for not knowing exactly how to satisfy a mandate if schools were required to make menstrual products “available for any gender who needs them.”5
Gender activists seem to want everyone to have access to public bathrooms that are safe and consistent with one’s gender identity. But conflating sex and gender makes it harder to arrive at a consensus on public policies and harder to communicate with people who may disagree. Some gender activists see sex-segregated bathrooms as a form of gender discrimination. And at least some of their legal advocates dismiss the argument that females need privacy and protection from predatory males.
Sports competitions, like public bathrooms, have historically been segregated on the basis of sex, not gender. In athletics, the process called “gender” verification should really be called “sex” verification. Because females participating in male sports are at a competitive disadvantage, sex verification is mainly female sex verification: it is done to athletes competing in the female category— to protect female athletes from unfair competition. The International Olympic Committee stopped mandatory gender (i.e., sex) verification in 1999. Historically, this was based on chromosome testing and medical exams; today it consists mainly of hormone testing. For obvious reasons, sex verification cannot be based on how one identifies.6
If the confusion over sex and gender were limited to the words “sex” and “gender,” the problem would be simpler. One of the more confusing aspects of modern gender discourse is the way academics and activists have redefined the terms “man” and “woman.” As scholars sought vocabulary to discuss social and cultural aspects of difference separately from biological aspects, the terms man/woman increasingly became associated with gender in academic discourse. Understanding this distinction in feminist theory helps make sense of otherwise confounding statements. The Office of Research on Women’s Health (part of the National Institutes of Health) explains on its website: “a person with typical female (sex term) sex traits may or may not be a woman (gender identity).”7
In Beauvoir’s analysis, sex and gender intersect. For Beauvoir, biological facts are the irreducible foundation on which gender is constructed. Before becoming a woman, one is born female. But female sex characteristics do not determine a woman’s life. If biology is not destiny, it nevertheless matters.
Today’s gender activists argue it is wrong to assume that one’s biological characteristics exert a significant influence on one’s gender identity. But men’s and women’s lives are shaped not only by their social roles and culture but by their physical characteristics. Today’s gender activists embrace gender identity in part because it seems more flexible and inclusive than biological sex. But dismissing biological sex as a misguided social construct only makes it more difficult to identify invidious sex-based distinctions. “Over time,” wrote the Guardian journalist Susanna Rustin, “the internal contradictions created by definitions that are subjective and unstable will, I think, pull gender-based feminism apart.”8
It’s unlikely that the various factions in the culture war will agree on the merits of “gender ideology” or “intersectional feminism” anytime soon.9 But the first step would seem to be agreeing on the meaning of words. Conflating sex and gender makes it harder to communicate medical screening guidelines, to agree on rules for athletic competitions, and to write clear, enforceable legislation. When different parties are using the same terms to mean different things, there’s bound to be confusion and conflict. Using sex and gender interchangeably makes a wide spectrum of important conversations even less likely to happen.
The term “gender activist” refers here to an advocate for social and political change informed by “gender identity,” a sense of self that may or may not be congruent with one’s “sex assigned at birth.” Sometimes called “gender ideology,” usually by its critics, this matrix of beliefs draws on Judith Butler’s influential critique of the sex/gender distinction in second-wave feminism. Gender activists contend that neither sex nor gender is immutable and binary. Gender identity is protean— it can change over time— and yet it may be necessary to bring one’s body into alignment with one’s gender identity. Many of the basic elements of gender ideology were popularized by Gender Spectrum, an organization founded in 2006 by Stephanie Brill to promote gender inclusiveness.
Leonard Sax has estimated the prevalence of intersex to be about 0.018% (100 times smaller than Anne Fausto-Sterling’s often-quoted number). Unlike Fausto-Sterling, he restricts the term to “those conditions in which chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female.” L. Sax, “How common is intersex? a response to Anne Fausto-Sterling,” J Sex Res. 39, no. 3 (2002):174-8. doi: 10.1080/00224490209552139.
Many institutions still uphold the postwar consensus. Take, for example, the Yale School of Medicine. Yale regards sex as “a classification, generally as male or female, according to the reproductive organs and functions that derive from the chromosomal complement [generally XX for female and XY for male].” Similarly, Yale hews closely to the postwar definition of gender as “a person's self-representation as male or female, or how that person is responded to by social institutions on the basis of the individual's gender presentation.” (In the words of the National Institutes of Health, gender encompasses “identity and expression, as well as social and cultural expectations about status, characteristics, and behavior as they are associated with certain sex traits.”) Carolyn M. Mazure, “What Do We Mean By Sex and Gender,” Yale School of Medicine, Sept. 19, 2021, medicine.yale.edu/news-article/what-do-we-mean-by-sex-and-gender/; “Sex and Gender,” Office of Research on Women’s Health, National Institutes of Health, accessed 4. Jan. 2025, orwh.od.nih.gov/sex-gender.
See, for example, E. Matteo Diaz, “Stop Telling Me There Are Only Two Sexes,” The Harvard Crimson, Feb 22. 2024, www.thecrimson.com/column/transcriptions/article/2024/2/22/diaz-stop-only-two-sexes/. Often cited in this context is Tom Laqueur’s Making Sex (1990), a cultural history of reproductive anatomy and physiology. Laqueur suggests that a “two-sex model” of the body— a model describing two fundamentally different sexes rather than a “one-sex model” that emphasized similarities in male and female anatomy— did not emerge until the eighteenth century.
Bali White, “Creating Safe Spaces: Why All-Gender Restrooms Are Essential for Health and Well-Being,” The EDI Pulse, National Institutes of Health, 5 June 2023, www.edi.nih.gov/the-EDI-pulse-blog/creating-safe-spaces-why-all-gender-restrooms-are-essential-health-and-well-being.
Irena Martínková, Taryn Knox, Lynley Anderson, and Jim Parry. “Sex and Gender in Sport Categorization: Aiming for Terminological Clarity.” Journal of the Philosophy of Sport 49, no. 1 (2022): 134–50. doi:10.1080/00948705.2022.2043755.
“Sex and Gender,” ORWH, NIH. Italics and parentheses are in the original.
Susanna Rustin, “Feminists like me aren't anti-trans – we just can't discard the idea of 'sex,’” The Guardian, 30 Sept. 2020, www.theguardian.com/commentisfree/2020/sep/30/feminists-anti-trans-idea-sex-gender-oppression.
For one faculty member’s experience with “gender ideology,” see Tiffanie Victoria Jones, “Gender Ideology Is Destroying Academia,” Journal of Free Black Thought, May 9, 2024, and “Gender Ideology Is Destroying Academia, Part II,” Journal of Free Black Thought, May 28, 2024.