Seventeenth-century French philosopher René Descartes had a habit of lying in bed until noon, just thinking. According to legend, he came up with the idea of Cartesian coordinates one morning as he watched a fly walking on the ceiling above him. Perhaps it was also during his pre-lunch lounging that he came up with his most famous saying: “I think, therefore I am.”

Descartes wondered how he could know for sure that his perceptions accurately portrayed the physical world. For that matter, how did he even know there was a physical world? What if some demon had cast a spell on him and everything he experienced was a hallucination? (Some readers may recognize this as the premise for the Matrix movies.)

In the end, Descartes decided there was only one thing he could be sure of, namely that he was aware of his own thoughts. In other words, Descartes’ mind was the ultimate reality, the only thing that absolutely existed. As for the physical world, well, it was probably real, but he couldn’t say for sure.

The notion that there’s a non-physical mind extending beyond the confines of the physical body is known as Cartesian dualism. Whether you call it a mind, a soul, or a spirit, some concept of a psychological self as the core identity of a person is probably a universal human experience. This leads us to the mind-body problem: What is the relationship between the mind and the body?

During the twentieth century, it became clear that the brain does indeed produce many of the functions that were traditionally assigned to the mind. Most psychologists today outwardly reject Cartesian dualism. “Minds are what brains do,” as cognitive scientist Marvin Minsky famously quipped.

Yet Cartesian dualism creeps back into the way psychologists think about their subject. For instance, neuroscientists talk about the “neural correlates of mental processes,” recognizing a relationship between brain activity and mental states without going so far as saying the first causes the second.

Another area where Cartesian dualism dominates thinking is in the field of human sexuality. Until fairly recently, the terms “sex” and “gender” have been used interchangeably in the literature. But now researchers are converging on a consensus: “Sex” refers to the physical attributes of the male or female body, while “gender” refers to the psychological experience of being a masculine or feminine person.

Incidentally, sexual orientation is a separate dimension from either sex or gender. Sexual orientation refers to the sex of other people you are attracted to, regardless of your own sex or gender. Thus, a man (that is, a person with a male body) can perceive himself as having a masculine gender (liking “guy stuff,” doing “guy things”), but have a sexual orientation toward other males. Probably most gay men see themselves this way.

The general population views sex/gender as binary categories—male/masculine and female/feminine. In contrast, some scholars and activists argue that both sex and gender extend along a continuum. There’s some truth to each view.

In the case of biological sex, almost everyone can be categorized as male or female. This is especially so if we use the simple criterion of penis=male and vagina=female. However, a few people are born with ambiguous sexual organs, a condition known as intersex. If we also consider secondary sex characteristics, such as angular face and broad shoulders for men or rounded face and wide hips for women, we see that people do extend along a line from extreme manly male to extreme womanly female.

However, this sex continuum isn’t like a rainbow, with bands of equal width. Rather, people’s sex is spread out according to what statisticians call a bimodal distribution—in other words, a double bell curve. Most men have average male body features, but a few extend out into the extreme manly range, while others have somewhat female characteristics. Likewise, most women have average female body features, with some extreme womanly types and others with somewhat manly characteristics.

We get the same double bell curve for gender. Most men and women are around the two midpoints, with a certain balance of masculine and feminine traits. Only a few are out on the extreme tails of the bimodal gender distribution.

For the vast majority of people, regardless of sexual orientation, psychological gender and biological sex more or less line up. But for some persons, there’s a mismatch between sex and gender, and they’ll express sentiments such as, “I feel like a man trapped in a woman’s body.”

Since this is an experience that few other people can empathize with, it’s long been considered a psychological disorder. But in recent years, psychologists have started using the term gender dysphoria (meaning “distress”) as opposed to gender identity disorder. In other words, the mismatch between sex and gender is not due to psychological malfunctioning. However, gender dysphoria does lead to psychological issues, in particular depression and anxiety, and these need to be addressed.

Gender dysphoria is an area where psychology still struggles to resolve the mind-body problem. There’s a lot of speculation about biological underpinnings for the condition, from genetic anomalies to hormone exposure in utero, but the findings reported so far in the literature fail to replicate in follow-up studies. So there’s still a lot we need to learn about this condition.

Since gender dysphoria is conceptualized as the distress that occurs when biological sex and psychological gender don’t match, the approach to treating the condition is to find a way to line up the two. In theory, you can change gender to match sex, or you change sex to match gender. As it turns out, it’s easier to change sex than change gender.

Sex reassignment therapy typically involves a hormone regimen that brings body chemistry in line with the perceived gender. This is then followed up by surgeries that reshape the body into the person’s new sex. The transition from male to female is usually more successful than from female to male, mainly because surgeons still don’t know how to create a functioning artificial penis.

These medical interventions are not without risks, however. In about a quarter of the cases, the distress that was interpreted as gender dysphoria continues even after sex reassignment is complete. In other words, the real cause of the dysphoria may have been something other than gender identity. And so, while sex reassignment therapy can help some people become happy and productive members of society, it also needs to be approached with the utmost caution.

Although psychotherapy is an important component in sex reassignment, counselors generally avoid therapies that involve reconciling psychological gender with the physical body. At least in part, I suspect, this is because such approaches smack of the “conversion therapies” that were once used—with disastrous consequences—to “cure” homosexuality.

But there’s a big difference. Same-sex orientation doesn’t lead to distress in and of itself. It’s only the negative social attitudes and having to deal with discrimination that create psychological problems. In an open society, homosexuals are just as happy and productive as heterosexuals. In contrast, people suffering from gender dysphoria are fundamentally unhappy with the disconnect between sex and gender that they perceive within themselves. In other words, they feel a need to fix something.

For some, changing the body to match the mind may be the appropriate solution. For others, an exploration of the issues underlying the dysphoria, with the goal of reconciling their gender identity with the body they have, may be more effective. Mental and medical health care providers treating people suffering from gender dysphoria need to be open to both approaches.

Most psychologists today disagree with Descartes. As scientists, we need to accept the primacy of physical reality, and our job as students of the mind is to explain how psychological experience relates to that reality. Yet when sex and gender mismatch, the Cartesian primacy of psychological experience still prevails. It behooves therapists dealing with gender dysphoria to examine the mind-body problem before recommending a course of action to their clients.


Cohen-Kettenis, P. T. & Steensma, T. D. (2016). Gender dysphoria. In J. C. Norcross, G. R. VandenBos, D. K. Feedheim, & N. Pole (Eds.), APA Handbook of Clinical Psychology: Psychopathology and Health, (pp. 395-406). Washington, DC: American Psychological Association.

Cousino, M. K., Davis, A., Ng, H., & Stancin, T. (2014). An emerging opportunity for pediatric psychologists: our role in a multidisciplinary clinic for youth with gender dysphoria. Clinical Practice and Pediatric Psychology, 2, 400-411.

Johnson, L. & Shipherd, J. (2016). The psychologist’s role in transgender-specific care with U.S. veterans. Psychological Services, 13, 69-76.

Sánchez, F. J. & Pankey, T. (2017). Essentialist views on sexual orientation and gender identity. In K. A. DeBord, A. R. Fischer, K. J. Bieschke, & R. M. Perez (Eds.), Handbook of Sexual Orientation and Gender Diversity in Counseling and Psychotherapy, (pp. 51-74). Washington, DC: American Psychological Association.

Schiffman, M. et al. (2016). Behavioral and emotional problems as a function of peer relationships in adolescents with gender dysphoria: A comparison with clinical and nonclinical controls. Psychology of Sexual Orientation and Gender Diversity, 3, 27-36.

David Ludden is the author of The Psychology of Language: An Integrated Approach (SAGE Publications).

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