Alex Byrne is a philosopher and a professor at MIT in the Department of Linguistics and Philosophy. He is the author, most recently, of Trouble With Gender: Sex Facts, Gender Fictions.
In this week’s conversation, Yascha Mounk and Alex Byrne discuss the evolution of the concept of gender and whether it’s useful for understanding social reality; why pediatric gender medicine struggles with questions about how to properly care for young patients; and how we can move towards a society in which transgender people can live with greater dignity.
The transcript and conversation have been condensed and lightly edited for clarity.
Yascha Mounk: You've just published a new book called The Trouble with Gender. It's a very interesting book in itself, but there's also an interesting backstory here, where it was meant to be published by one of the premier academic presses in the world, but there was a kind of rebellion against it.
What happened in this process, and what was so unusual about it?
Alex Byrne: I became interested in the general topic of sex and gender a few years ago, and I'd written a few things for a popular audience on whether sex is socially constructed, whether sex is binary. A book was brewing. I thought a general interest book was needed on this topic, treating the issues from a philosophical perspective. Of course, I knew the whole topic was radioactive. It's kind of one of the third rails at the moment in the academy and outside. And I published a scholarly monograph with Oxford University Press before, on self-knowledge. And I had a great experience with them. To cut a long story short, eventually OUP gave me a contract, they were very enthusiastic about the book and they said they would promote it for a general audience. And then I started to write the book in 2021 with the OUP contract and then various things happened in the interim. So one thing that happened was that there was a big fuss, a protest over OUP's publication of another book on sex and gender by the University of Melbourne philosopher, Holly Lawford-Smith. This was called Gender-Critical Feminism. And Oxford, to their great credit, faced down this protest quite well, but I think it's very likely that they were spooked by the whole episode.
And after that, I had an invited chapter on pronouns—as in he, she, they, them—canceled by OUP, which was extremely unusual, basically unheard of. You don't invite someone to write, unpaid, a chapter in an OUP handbook and then refuse to publish the chapter without allowing the author to make any revisions. But that's exactly what happened. In my case, one of the editors of the handbook actually announced that they would not be publishing my chapter on Twitter. So the whole thing was just completely outrageous. And then Holly Lawford-Smith had run into some other problems with OUP when she was working on her second book, again on sex and gender, called Sex Matters.
My book was canceled by OUP fairly soon after I submitted it in 2022. And what normally happens is that you get a contract, you submit a draft, you then get reviews back from expert reviewers, you then make revisions and the process maybe iterates a few times and eventually the book is published. It's extremely rare for the book not to be published. It's even rarer for the draft manuscript to be rejected without inviting any revisions whatsoever. But that is what happened in my case.
Mounk: And what was the stated logic here? What is it that Oxford University Press said was wrong with the book?
Byrne: Well, there was just one line in the rejection email to the effect that the book didn't treat the subject in a sufficiently serious and respectful way. That was it. So there were no examples given of this lack of respect or lack of seriousness. The claim about lack of seriousness was particularly annoying because, as you'll see, if you've looked at the book, you'll notice that there are a huge number of endnotes and a massive list of references. So the idea that I didn't treat the subject seriously is a little ludicrous.
Nothing was identified in the book as particularly problematic. There was no reference to any specific poor argument that I'd made or specific error that I had committed. And I think it was clear why OUP didn't try to argue their way into rejecting the book because of course then I would have had an opportunity to say I don't agree for this reason. I wasn't given that opportunity. I think it was clear that they just didn't want to publish the book. So the easiest thing to do would be just to make this blanket, vague condemnation of the book.
Mounk: Well, thankfully the book was picked up by Polity, and it is now out in the United Kingdom and the United States. Let's delve into this subject, which is an important one that does deserve to be treated with seriousness. And it's one that I think has a lot of people understandably confused.
Why don't we start with a very basic set of questions: What is biological sex and what is the notion of gender and how are those different? Why is it that we need this additional category of gender in order to make sense of the world?
Byrne: Just to start with biological sex, there's a chapter in the book called “Clownfish and Chromosomes,” which is all about biological sex. I mean, there's a huge amount of confusion on this topic, both in philosophy and gender studies, which I try to unravel in that chapter. And as far as the question “What is sex?” goes, here I just lean on the absolutely standard textbook account of what the two sexes are. In a nutshell, to be male is to have a body plan that is designed to produce small gametes, sex cells, i.e. sperm. And to be female is to have a body plan that's designed to produce large gametes or sex cells, i.e. eggs. So this distinction between male and female has nothing in particular to do with primary or secondary sex characteristics like having a penis or having a vagina or having breasts. It has nothing to do with having XX chromosomes versus XY chromosomes.
There are plenty of sexed animals—of course, plants also come in sexes—that have no sex chromosomes at all. So the relevance of sex chromosomes is simply, in the case of mammals, to be the mechanism by which organisms come to be male and female in the first place; it's part of the sex determination mechanism. Other animals have different sex determination mechanisms. I mean, some animals have temperature-dependent sex determination mechanisms; depending on the ambient temperature when the eggs hatch, that's going to determine whether the animal pops out as male or female. So that's what the two sexes are. That is straightforward. Though if you read the philosophical or gender studies literature, sex, according to that literature, is often portrayed as this sort of confusing mélange of traits like chromosomes, hormones, genitalia and so on.
And sometimes people say which traits we pick to define the sexes depends on the context, perhaps also on our political aims. Further, some people have suggested—the biologist and gender studies theorist Anne Fausto-Sterling is an example—that there may be more than two sexes: She once suggested that there are at least five. And just to add to the confusion, it's often said—again, Fausto-Sterling is a source for this—that a significant proportion of the population is intersex, neither male nor female. So being neither male nor female is supposedly as common as having red hair, close to 2% of the population. All that according to me is just completely wrong. There's no truth to that whatsoever.
Mounk: So perhaps there’s two natural kinds, which are organisms that produce large sex cells and organisms that produce small sex cells. The question though is why is that the definition of male and female, particularly because as I understand it, there could be some circumstances in which an organism that produces large sex cells, that ordinarily would be an egg-producing biological female, will present (and this is the point made by those who focus on intersex conditions) in a way that in very important ways appears to be male—for example, by having a penis or by having anatomical features that look to us more narrowly male.
Why is it that the question of whether we are large sex cell producing or small sex cell producing creatures should be taken to be definitive of our understanding of sex? It may be definitive of something, it may be some important distinction in the world. But why is it obviously the distinction we should use to define biological sex?
Byrne: Well, perhaps it's not completely obvious, but if you look at the wide range of males and females across the animal and plant kingdoms, it's the only account that makes any sense. Certainly an account in terms of appearance—broadly speaking, primary or secondary sex characteristics (having a beard or a penis or whatever)—is absolutely not going to work.
Asparagus plants come in male and female varieties, and a male asparagus plant is just as much a male as you are. Being male just can't amount to these superficial features. And, of course, biologists themselves recognize that some males, for example, appear just as females and some females appear just as males. So for example, the female hyena has a fake penis, a clitoris, through which it gives birth, which looks just like a penis and also a fake scrotum. And the female hyena is also very aggressive. So in a way, the female hyena is more male than the male hyena, but the biologists do not think that the females are really the males. They know perfectly well what's going on: these are females that in certain respects behave and look just like males.
Mounk: So we've discussed the concept of biological sex at good length now. Do you believe that the concept of gender is nevertheless useful?
Broadly speaking, the way I understand it is to say that there's biological sex, and biological sex has historically come with a certain set of gendered expectations, which is to say that depending on the society, there's been assumptions about how men act and how men should act, and how women act and how women should act. I take it that the concept of gender was used to critique the expectations that have historically come with belonging in a particular sex category. And that surely sounds like a useful concept.
And then I guess in the second step, there's then the idea that perhaps we do have some amount of useful gender expectations that correlate with biological sex (and here you can see how some of the trans discourse actually in an odd way can be a little bit traditionalist). But if we're comfortable with that, if it's fine to have certain sets of behavioral expectations around what it is to be a man and what it is to be a woman, then perhaps there are certain members of the category of biological males who prefer to live in keeping with the expectations that have historically been applied to women. And those may, in our parlance, be trans people. One way of understanding them is to say they are biological males who, for whatever reason, whether that's an innate, inborn thing or whether it is not believe that they would rather put on dresses and speak in a more feminine way and whatever set of expectations our society happens to have about what it is to act as a biological female.
What do you make of that notion of gender and that justification for at least a thin notion of what it would be to be transgender and, perhaps, to respect that choice?
Byrne: Just to start with gender, the original sex-gender distinction was made by the UCLA psychiatrist, Robert Stoller, who in 1968 wrote a famous book called Sex and Gender. And in Stoller's hands, the notion of gender didn't play the role that you mentioned. It wasn't intended as part of some critique of gender norms or gender stereotypes or anything like that. Stoller defined gender as the amount of masculinity or femininity found in a person. And which was, if you think about it a bit, a pretty terrible definition. It makes it very hard to use that word. But it also renders the question, “what gender are you?” somewhat nonsensical. But Stoller's distinction was picked up by in particular the British feminist sociologist Ann Oakley in the 1970s, and a lot of second wave feminists ran with that distinction, modifying it a lot along the way. And as you said, in one version of the distinction, it's between sex on the one hand and sex-typed social roles, sex-typed social expectations or sex-typed norms on the other. So there's a distinction between male and female on the one hand, and how males and females actually behave in a particular society, how they're expected to behave in a particular society, and so on. And this of course is a genuine distinction. There really is a distinction between being a female on the one hand and behaving in a certain culturally circumscribed way on the other or being subject to a set of norms that apply only to female people.
These are all useful distinctions. I mean, they're kind of obvious distinctions if you think about them. It's not some great discovery that there is such a distinction. You can find such distinctions back in the ancient philosophers, Plato, for example, even though of course they didn't use the word gender to mark that distinction. Now, I think that because gender has another very common meaning, namely as a synonym for sex. It's just incredibly confusing to draw this distinction between sex and sex-typed norms or sex-typed social roles using the word gender. It just leads to no end of confusion. And gender also has other meanings as well within philosophy and gender.
Mounk: So one way of putting a point is that in the word “gender norms,” you could actually just substitute it with “sex norms,” and it would mean much the same thing.
Byrne: Yeah, that's exactly right. The reason why the word “gender” came to mean “sex” is that it usefully disambiguates sex. So sex itself, just like numerous other words, is ambiguous, of course, between the intercourse sense and the male and female sense. And these days, of course, we talk about sexual intercourse all the time. It's like 24/7. And we do that using the word sex. So it's very useful to have another word that means male or female so we don't get confused.
That explains why gender became a very popular replacement for sex in the male or female sense. And that is not going away. So given that there is this constant pressure to use gender to mean male or female, introducing or stipulating another sense of gender to mean sex type, social norms or masculinity and femininity or gender identity—that's another sense of the word gender. It just piles confusion upon confusion. The first thing you ought to ask when reading anything that's written about sex and gender, which just throws around the word gender is “What on earth did the authors mean by the word gender?” And it's often extremely unclear. In fact, in the work of Judith Butler, it is notoriously unclear what she means by gender.
Mounk: So what about the kind of core sense of this that some members of the trans movement would point towards, which does seem to have an obvious first order plausibility, which is to say, let's use the term “sex norms,” right? There are certain norms associated with your biological sex in the United States, even in 2024. And some people don't want to live in accordance with those sex norms, right?
Even though they are, for example, biologically male, they prefer to wear dresses and high heels and to have painted fingernails; they prefer to speak in a more high-pitched voice and do whatever else we would ordinarily associate with biological females in our culture. And that is a helpful distinction to make between their biological sex and their preference as to how they want to lead their lives. And therefore, to the extent possible—and we can go on to the debate about when there's real trade-offs involved—we should treat them with respect and allow them to do that: If they prefer to live as though they were biological women, in a liberal society, in which we believe that people are self-determining and in which we uphold something like the harm principle, we should say “Well, why on earth not? You do you.” Right?
Byrne: I completely agree. Of course you mentioned Mill's harm principle, which is extremely relevant because of course there are some tricky cases involving males where the harm principle does seem relevant. But perhaps another distinction would be useful.
Let's just think about children for the moment. Of course, some male children, for whatever reason, are, if you like, naturally very feminine. And this is highly correlated with growing up to be a gay man. And of course you can be a very feminine fingernail-painting, high-pitched male who is perfectly happy being a male and identifies as a man and just grows up to be this very feminine man. So there's a distinction between the very feminine man and a natal male who suffers extreme distress, gender dysphoria, and at some point transitions, perhaps with the help of surgery or hormones, to live as a woman. So these are two very different outcomes for a young male child who's very feminine from the get-go.
Of course, the really difficult hot-button issues concern the treatment of gender dysphoric youth, whether, for example, they should be given puberty blockers. This was a huge issue in the UK, which ultimately led to the ending of the gender identity development service in the UK. It was closed down, partly due to various scandals involving puberty blockers. So that's one issue. And then of course another issue is now, turning to adults, whether you allow natal males who've gone through a male puberty, but who live as women, to compete in the female sporting category, for example, or you allow them to go into rape crisis centers, just like any natal female. These are not trivial issues that I think can be brushed aside. There are serious questions here.
Mounk: So let's start with the first set of these questions, perhaps. I suppose I see two complications here. One is that what we want is a society in which people are empowered to make life choices that are going to serve them well and make them happy and have a worthwhile life. And certainly overcoming a constraining binary gender or, if you prefer, sex norms, which say that if you're born into this category you must act this way and if not there's something defective about you and we're going to socially shame you, is a terrible and very violent thing that we want to overcome.
Of course, the question is how best to overcome that, and you might think the best way to overcome that is either allowing people to transition to live in accordance with the sex norms that don't correspond to their biological sex. Or you might say it is allowing people to present however they wish on a much broader range of forms of expression. And to some extent—and I think this is one concern that you hear from some gay men and some lesbian women—this particular form the transgender movement has taken can cut against that, so that you're telling that young, effeminate boy not that it is fine to be a boy and be effeminate, that there have always been men who are more effeminate and that's one possible way of being a man; but rather, if you're effeminate, if you prefer to play with dolls, then you must truly be a girl or a woman and you must transition.
The second set of complications, as you pointed out, is about biological transition, in particular in younger people. So perhaps you can help us puzzle through that a little bit. What was the concern with the Tavistock Clinic in England run by the National Health Service that got it closed down? Why is it that some people who don't see themselves as reactionaries have genuine concerns about the way in which younger children or teenagers are given puberty blockers or go through transitions in the United States today?
Byrne: There's a great book about the closure of the Tavistock Clinic and the events leading up to it by the journalist Hannah Barnes called Time to Think, which I thoroughly recommend. And I'm probably not going to get all the details exactly right, but some years ago in the UK, a case for judicial review was brought by a woman called Keira Bell, who was treated by Tavistock, given testosterone. She had a double mastectomy, and then she decided that all this was a big mistake. And that I think opened the floodgates somewhat and Tavistock's practices began to be more carefully scrutinized. And they had adopted the so-called Dutch protocol for treating juveniles with gender dysphoria, which was started to be developed in the ‘90s and involved giving so-called puberty blockers very early in puberty. And the original thought was that these drugs would function as a pause button. They would allow “time to think.”
But then it turned out—perhaps not surprisingly, in retrospect—that puberty blockers seemed to be a fast forward button rather than a pause button. Something like 95% of children put on puberty blockers—I think these are Tavistock’s own figures—went on to take cross-sex hormones and to medically transition. And so that's one issue. And then another issue is just the health impacts of puberty blockers themselves and whether they actually help with kids' mental health: There's really not very much evidence that they're particularly effective in that regard. And of course, this is an extremely serious issue because (this is just a general point, it has nothing to do with the transgender issues specifically) all else equal, you want to avoid contact with the healthcare system as much as possible. Especially, you don't want to go anywhere near a surgeon if you can possibly help it.
Again, this has got nothing to do in particular with trans issues, but if all else is equal, you can choose the path of not having surgery and hormones, which have like enormous health complications, then that's what you should do. So the first line of treatment should really be to encourage people to be comfortable living in their own sex bodies, rather than giving them puberty blockers, which just seems to speed up the process of medical transition, in which case you end up as a lifelong medical patient. Of course, if the first line of treatment doesn't work and the dysphoria persists into adulthood and you find you just can't live in your natal sex, then sure, go ahead and transition. But it does seem to be remarkably irresponsible, in my view, to treat medical transitioning for children as just some regular piece of medical care with clear benefits, whereas it's really very experimental and the evidence base for it is severely lacking.
Mounk: Or to put it perhaps in a milder way, in any medical treatment, you want to understand the trade-offs, right? You take aspirin and you have the indication of aspirin, what it is that aspirin allows you to do, and you have a long list of possible side effects of aspirin, and you are supposed to weigh those two against each other. And of course, sometimes it makes sense to pop aspirin, but you should think about the trade-off before you do. I think one of the things that I found striking in the debate about this is the unwillingness to acknowledge that there's a difficult trade-off here.
I agree that by all accounts there are people who suffer from terrible gender dysphoria, who suffer from being in the body they are born into, who feel that this somehow is unbearable and that at least in some cases, that seems to lift after they transition with surgery and other things. And so that's the prima facie case for allowing people to undergo those treatments in general and perhaps even at a young age. Now, of course, the trade-off that you have to look at as well includes things like the fact many of these people become infertile and that this is a very difficult thing to make decisions about when you're 15 or 16. Secondly, there seem to be some serious concerns, for example, about the potential loss of bone density because it is when going through puberty that you have a great increase in bone density and so on. And there's just some questions about what the health of some of these people are going to be when they're 70 or 80 years old, whether they're going to be significantly weakened by this, much more subject to dangerous injuries, like breaking their hips. And then third, of course, there are the cases like Keira Bell—whose story she actually published, for the first time, in Persuasion—to regret transitioning. And there is a very heated, very complicated debate about how high the rates of detransition are.
But what I don't understand about this, and what I have become very saddened by, is that all of this is treated as in some way being anti-trans—that may be true of certain people in this debate, but it's certainly not true of most of the people who have these concerns, including clinicians who have worked with these populations for a very long time who are attracted to this field because they had a lot of empathy for them, but who came to worry that they perhaps in certain cases are doing harm.
Byrne: I think that's exactly right. And you raised a very important point about fertility and consent which I forgot to mention. I mean, sometimes you get the impression from the more overheated rhetoric that skeptics about youth gender medicine are rather like skeptics about vaccines, as if their positions are just as implausible.
There's a phrase that often gets flying around, namely that gender affirming care is “life-saving treatment.” And so the opponents are portrayed just as people who are, in effect, skeptical of a vaccine: “Here is this treatment which saves many, many lives a year and for some perverse reason, you bigots are against it.” But there's no evidence whatsoever that this treatment is life-saving. It may well be beneficial in some cases, but obviously before the Dutch protocol came along, there's no evidence that hundreds or thousands of children were committing suicide or dying prematurely through lack of gender affirming treatment. You're absolutely right, that this is a complicated matter of trade-offs, complicated ethical issues about consent.
Mounk: How do we puzzle through this? On the one hand, we have established the general presumption that if people want to live in accordance with the norms of a particular kind of gender, then they should be able to do that. And if that means they'd rather play on the women's team than the men's team, in principle, there shouldn't be a problem. The worry, of course, is that people who have gone through male puberty, who have gone through puberty as biological males with the levels of testosterone that this involves, would end up having a competitive advantage over biological women in virtually all sports. So how do we resolve this tension or this trade-off?
Byrne: Okay, that is an excellent question. Maybe I should say just one thing. First of all, I mean, you already alluded to it with male puberty. This has got nothing to do with some anti-transgender prejudice, as the case of trans men—that is, natal females who take testosterone and transition to live as men—shows.
They have not gone through male puberty. They pose no competitive threat to natal males competing in athletic categories. So there should be no issue and indeed there is no issue about whether they can play on the men's team. Go right ahead. So if the position were symmetrical for trans women, there would be absolutely no issue, but it isn't symmetrical because male puberty does give you, through testosterone, as you said, a considerable athletic advantage. Now, sometimes people say, what about Michael Phelps? He is an exceptional male in certain respects. We don't ban him from swimming just because, I don't know, he has exceptionally low levels of lactic acid or large feet or something like that. And that's true. But Michael Phelps is a developmentally ordinary male. There's nothing qualitatively different about him compared to other males, whereas the male and female body are really quite different.
The University of Pennsylvania swimmer Lia Thomas is an example. They really are quite different from females, even setting aside abstract issues about fairness or whatever, just as a practical matter. Given that there are so few of these people and given that they make, as it were, a huge splash when they do win and people get really annoyed and lots of women complain and say, “Gosh, why can't we just have a category for females? Why can't we just celebrate the female body?” Given all that, I think it's perfectly reasonable to exclude natal males who've gone through male puberty from the female category. And there's an easy fix, which is just to turn the category for men into an open category. And there should be no presumption that if you enter the open category, you live life as a man. It's perfectly consistent with entering the open category that you live life as a woman.
Mounk: Finally, let me just understand one thing, which is that you have an interesting philosophical contribution to make, but much of our conversation ended up feeling less philosophical, or at least I wasn't always able to see sort of where the line was. So to what extent do these questions actually hinge on philosophy? And to what extent do they hinge on simply taking into account the interests of different people in a reasonable way and having a realistic view of how social institutions work? To what extent does what we should do about trans questions actually turn on these fundamental philosophical questions?
And then secondly, I have to say that after all of this conversation, I'm a little bit baffled about what is so controversial about this book. So, why is it and what is it about this conversation that is supposed to have been so un-serious or so concerning?
Byrne: Even though we've talked about social and political issues, including youth gender medicine and who should compete in what sporting category, that is not what the book is about by design. I wanted to decouple the social and political issues, questions about what we should do, what policies we should adopt, from the more descriptive, factual questions: What is a woman? What is gender identity? Do we all have gender identities? What are the differences between human males and females? There's even a chapter on patriarchy and what explains the persistence of patriarchy throughout history. And then there's a chapter that we didn't actually touch on at the very end about identity and the true self. And there are all these questions, the answers to which are often taken to be highly relevant to the social and political issues.
And I suppose one moral of the book is that there's really no straight line from the answers to these questions to policy. So there's no straight line, in particular, from answers to questions about what a woman is to policies about who should be allowed to compete in what sporting categories. But the more factual descriptive questions are, I think, just fascinating in themselves. Everyone is fascinated by these issues. And so they certainly deserve an entire book, but the book itself doesn't pretend to settle the social and political questions insofar as it bears on them. It's to suggest that there's less of a connection between the answers to these factual questions and questions about policy than is often assumed.
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Alex Byrne on the Trouble with Gender