What Is a Woman? Applying Thomistic Principles to the Case of Complete Androgen Insensitivity Syndrome

Abstract

Even in extremely conservative circles, the question “What is a Woman?” is controversial when one examines the case of persons with Complete Androgen Insensitivity Syndrome (CAIS), wherein the person has XY chromosomes and testes, but due to a total inability to respond to testosterone, the person develops in all ways in a feminine fashion (the person will also be infertile). Some Thomist scholars have argued that these people might be sexless, or that we cannot determine what sex they are, or that they are women. Using Thomistic principles of human sexuality, teleology, hylomorphism and the conclusions of biology, I will argue that these persons are ontologically male, albeit with a severe disorder of sexual development (DSD). Thus, these persons are not eligible for Catholic marriage. Then, I will suggest that these men (who have the bodily and psychological features of women) should live as women in society, thus proposing an authentically Thomistic “trans-genderism” which differs totally from the ordinary use of the term.

1. Introduction

This paper will use a Thomistic account to argue that persons with Complete Androgen Insensitivity Syndrome are ontologically males. Yet, due to the incredibly difficult Disorder of Sexual Development of these people, they ought to be allowed to live as females. However, since these people are male, but cannot complete the sexual act as a male, they cannot enter into Catholic marriage. The Thomism this paper relies on is grounded in the hylomorphic account of the human person, a teleological understanding of the body, and Aquinas’s principles about the metaphysical origins of sexual difference. Also, this paper engages Thomistic accounts about how to identify a person’s sex.

First, this paper briefly summarizes Aquinas’s metaphysics of human sexuality. Second, it examines the biology of sexual development. Third, it reviews various ways that Thomists identify a person’s sexuality. Then, it applies their methods to the case of Complete Androgen Insensitivity Syndrome in order to test them. This paper ends by proposing a Catholic, Thomistic “transgenderism.”

2. Aquinas on the Metaphysics of Sexual Difference

In De ente and Q. D. De anima, Aquinas states his basic position on the metaphysics of human sexuality. Aquinas’s position is that sexual difference stems from the body and not the soul. In the main articulation of this view he writes, “Some accidents follow from the order the matter has to a special form, as the masculine and the feminine in animals, the difference between which is reduced to the matter, as the Philosopher says in Metaphysics 10.9. Hence, the form of the animal having been removed, these accidents do not remain except in some equivocal sense” (Aquinas 2017, c. 6).1

The context of this statement is that Aquinas is discussing accidents and their essences in chapter six of De ente. He explains that accidents do not have their own distinct essences apart from the substance in which the accident adheres. For example, there is no such thing as pure blueness, only blue things. Yet, like substances, the essence of an accident is its definition. Since accidents only exist in a substance, the essence and the definition of an accident will include reference to the substance in which the accident adheres. Logically speaking, but not temporally, the substance must precede the accident in existence. Aquinas notes that accidents can either stem from the form of the composite substance or from its matter. There are two kinds of accidents that stem from the matter. First, there are accidents that “stem from matter in relation to the specific form” (ibid., c. 6). Second, there are accidents that “stem from matter in relation to the generic form” (ibid., c. 6). Aquinas says that sexual differentiation is the first category. Sexuality (i.e., being male or female) is an accident that stems from the matter in relation to the specific form. An example of the other type of accident that stems from matter (i.e., an accident that stems from the matter in relation to the generic form) is skin color. Aquinas explains that the first type of accident (i.e., accidents that stem from the matter in relation to the specific form) are reduced to matter, “Some accidents follow from the order the matter has to a special form, as the masculine and the feminine in animals, the difference between which is reduced to the matter, as the Philosopher says in Metaphysics 10.9. Hence, the form of the animal having been removed, these accidents do not remain except in some equivocal sense” (ibid., c. 6).

One difference between accidents stemming from matter in relation to the specific form and those in relation to the generic form is that after death those accidents stemming from matter in relation to the generic form remain in the corpse (a corpse still has the same generic color). Hence, material accidents stemming from the generic form refer to accidents of a body in general (accidents of a body qua body), while material accidents from a specific form require the form to be present, thus they are accidents of the composite substance as such and not just accidents of matter in general. For this reason, only actively living composite substances can have sexual difference. As Aquinas says, a corpse does not possess sexuality properly speaking.

Elsewhere, in Q. D. De anima, Aquinas writes, “There are three genera of accidents: some are caused by the principles of the species, and are called proper accidents: for example, risibility in man; others are caused by the principles of the individual, and this class is spoken of in two ways: first, those that have a permanent cause in their subject, for example, masculine and feminine, and other things of this kind, and these are called inseparable accidents” (Aquinas 1949, q. 12, ad 7).

From these quotations several key things about Aquinas’s basic position on this topic are made clear. First, sexuality or sexual difference stems from our animal and bodily natures, from the matter and not from the soul or form.2 Secondly, sexuality is an essential, inseparable accident of the human person—each human must be either male or female and sexuality (i.e., maleness or femaleness) is only properly present when the person is alive (nonhuman sexuality, that of animals, is found only in living animals) (Gondreau 2021, p. 210). Third, and related to the second, men and women have the same type of substantial form or soul—both are human.

Aquinas’s view that sexual difference stems from the individual’s body is essential to the argument that this paper presents below.3 It teaches us to look to the body to identify which sex a person is.

3. Sexual Development in Utero

Biologically speaking, sexual differentiation begins at conception with the difference in chromosomes, specifically, the 23rd chromosome of the sperm of the father which is Y for males or X for females (Fortin 2008, pp. 26–27). The chromosome of the egg provided by the mother is always X. Sexual development does not begin until about six weeks after conception (Hooven 2021, pp. 58–59). Thus, it is accurate to say that sex is determined at conception (based on the chromosomal type of the sperm which fertilizes the egg) but does not yet fully exist. This is analogous to one’s eye color, which is genetically determined at conception but will not become actualized until later in the person’s development (Fortin 2017, p. 408). Sexual development begins about six weeks after conception when the SRY (Sex Determining Region on the Y Chromosome) gene on the Y Chromosome activates, triggering the production of the protein TDF (the Testes Determining Factor) (Hooven 2021, pp. 58–59; Fortin 2008, p. 27).

The biological material, the flesh, which will become either the testes or the ovaries, is undifferentiated prior to this point of gestation. The same piece of flesh will develop either into testes or into ovaries. The TDF triggered by the activation of the SRY causes this undifferentiated material to develop into testes. Absent this effect, the undifferentiated proto-sexual gonad will develop into ovaries (Hooven 2021, p. 60; Fortin 2008, p. 27).

The internal sexual organs (cervix, uterus, and fallopian tubes for women and seminal vesicles, epididymis and vas deferens for men) are made from separate pieces of material in the embryo. In every embryo, they are ordinarily both the Mullerian ducts (which in female development become the cervix, uterus, fallopian tubes, and upper vagina) and the Wolffian ducts (which in male development become the seminal vesicles, epididymis and vas deferens). The base track of fetal sexual development would be for the Wolffian ducts to recede and the Mullerian ducts to develop into internal female sexual organs. But, if testosterone is present, then the opposite happens and the Mullerian ducts recede and the Wolffian ducts develop into the male internal sexual organs (Fortin 2008, pp. 27–28). Other hormones play a key role here. The testes produce AMH (Anti-Mullerian Hormone) which causes the Mullerian ducts to recede and for the full development of internal female sexual organs more estrogen is needed from ovaries (Difference Between Müllerian Duct and Wolffian Duct 2022).

The external sexual organs (vagina and penis) are like the gonads (ovaries and testes), in that they develop from the same, previously undifferentiated, flesh. In the absence of testosterone, this flesh develops into a vagina, but testosterone (and other androgens, but chiefly testosterone) causes it to develop into a penis (Fortin 2008, p. 27; Fortin 2017, p. 410). This development begins around eight weeks after conception (Hooven 2021, p. 62).

One can easily see that the default sexual development of a human fetus is female. For male development to successfully occur the SRY gene, TDF, and testosterone (and other androgens) must interrupt and redirect the developmental path (Buskmiller and Hruz 2022, p. 66). Once the testes are producing testosterone, that testosterone has further masculinizing effects on the rest of the body, including the brain. If ovaries develop, then the estrogen produced has feminizing effects on the woman’s body, including the brain (Fortin 2008, pp. 34–35). The order of normal biological sexual development thus goes: first chromosomes at conception, then gonads are differentiated around six weeks later, then the gonads produce different hormones which have opposing effects on the other sexual organs and the rest of the body, including the brain (Sodergren 2022, pp. 106–8).

4. Various Thomist Positions on Identifying Sexuality

There is disagreement within Thomist circles about how to precisely identify which sex a person is, over which features are key. This disagreement probably arises due to the reality of Disorders of Sexual Development (hereafter DSD). DSD name a range of conditions where a person’s biological sexual development diverges from the normal progression;4 at some point in the normal development of an XX girl or a XY boy something occurs which prevents the normal development from occurring. People with DSD may not have normal sexual characteristics of either sex (ambiguous genitalia which are not clearly a penis or a vagina) or they may have a mix of sexual characteristics of men and women.

Ordinarily, sex is simply determined by the chromosome type provided by the father’s sperm. The presence of the Y chromosome normally orders the sexual development into the male pattern by the SRY gene activating, causing the undifferentiated sexual gonads to develop into testes and then testosterone causing most of the further masculinizing of the fetus including genitalia developing into a penis instead of a vagina, masculinizing the brain, normal male-type bone and muscle structures, etc. Since nature is always or for the most part,5 altering the normal mode of identifying which sex one is (by the chromosomes, specifically the SRY gene on the Y chromosome–recall that SRY is short for Sex Determining Region on the Y Chromosome, thus it is scientifically clear what determines sex, the SRY gene) due to rare and unusual circumstances (i.e., DSD) is odd and shows an undercurrent of empiricist-style thought wherein a rule must hold true one-hundred percent of the time, like the laws of nature.

Nicanor Pier Giorgio Austriaco helpfully notes that healthy sexual development requires many things working together and cannot be reduced to the SRY gene alone (Austriaco 2013, p. 713). Yet, the SRY is the main factor in the process and begins the process in the development of the male. Austriaco then uses the Thomistic principle that action follows being to argue that we should most precisely identify an individual’s sex by the type of acts they can do (i.e., whether they produce sperm or eggs) (Austriaco 2013, pp. 713–14). Austriaco goes on to note that in cases of severe DSD where the individual produced no sexual gametes (neither sperm nor eggs) his mode of identifying the sex of the person simply would not work. He concludes that the sex of such persons is unknowable, at present at least (Austriaco 2013, p. 714). This is an unacceptable solution (a reductio ad absurdum) and proves his method for identifying the sex of individuals is inadequate.

John Finley gives a similar function-based approach. He follows Aristotle and Aquinas to define the male as the one which generates in another and the female as the one which generates in itself (Finley 2015, pp. 610–11; Finley 2022, p. 6). He uses this to argue that sex reassignment surgery (hereafter SRS) cannot truly change one’s sex since it renders one sterile (Finley 2015, p. 613). Also, he asserts with Austriaco that in cases of severe DSD a person’s sex cannot be known (Finley 2022, pp. 32, 43).

Similarly to Finley, William Newton defines men and women by their ability to produce their sex-specific type of sexual gamete, by their sexual organs, internal and external (Newton 2020, p. 200). Critically, he expands his position by saying that it is the individual’s teleological ordering towards developing these organs that determines sex, not the actual development of the organs in question (Newton 2020, pp. 200–1). Thus, Newton makes a crucial point, that the Y chromosome has a teleological ordering to produce a male, to develop the fetus along the male developmental path. Even if the fetus never develops due to early death or other health issues (i.e., DSD), the fetus is a male or female by the purpose of its matter. Thus, Newton puts the identification of the person’s sex ultimately on the chromosomes.

Paul Gondreau concurs that it is the chromosomes which determine one’s sex, “Sexual difference owes not to the soul, but to the biological design of our animal-like bodies, to ‘animal nature,’ as Aquinas again puts it, ultimately to the XX and XY karyotypes” (Gondreau 2021, p. 212). Gondreau shows he is considering the teleology of the Y chromosome when he repeatedly points to it as the root of sexual difference, since it causes the rest of the differences between the sexes (Gondreau 2021, pp. 187, 195–96).

Timothy Fortin also defines sex according to the chromosomes and their teleological ordering:

The beginning of sexual difference in a new human being depends upon which of those sperm–the one bearing the X or the one bearing the Y–wins the race to the heart of the awaiting ovum. Thus, the first determination of a new human being as male or female follows from this material disposition and is coincident with his or her first act of existence. Yet, it is not so much the genetic composition in itself that defines sexual difference as that to which the genotype disposes the new individual. Thus, at the moment of conception, each individual is determined to his or her sex, though not yet possessing that sex in act, much like one with a gene for blue eyes is determined to have blue eyes but does not yet have them in act.

(Fortin 2017, p. 408)

He later further stresses that it is the teleological ordering of the chromosomes which determines sex. In a footnote he says:

Though the first six weeks of development appears to be indistinguishable, it does not seem to be correct to say that this newly forming organ stands in equal potency to become either gonad. We shall see when briefly examining the intersex disorders that it is almost never the case that, when gonads attempt to form in a manner contrary to the genetic determination, they result in healthy, functioning organs. Such situations almost always result in sterility. Thus, it is clear that the genetic determination truly disposes the matter for one form over the other.

(Fortin 2017, p. 409)

The mistake I want to avoid is to identify one’s sexuality by developed organs. From a Catholic and Thomistic perspective, there are two issues with this approach. First, it is simply not looking deep enough nor considering the teleology of the chromosomes which lead to the organs. Second, it risks exposing one to objections from SRS. Currently, SRS leaves one sterile. But this may not always be the case. It is possible that a female-to-male transgender person could receive a testicular transplant and thus be able to produce sperm and reproduce in the male mode.6 Uterine transplants are effective and can currently be used to have one successful pregnancy. There have not yet been uterine transplants into a male-to-female transgender individual, but people are working on this technology and it is sure to occur soon (Richards et al. 2023, pp. 390–91). Further, ovarian transplants are possible and effective and can lead to natural pregnancy (albeit the ovary does not continually produce new eggs like the testes produce new sperm so ovary transplants seem more akin to egg donation) (Silber 2016). Thus, it seems that if transplant surgeries become effective enough then SRS surgery could make a transgender person fertile according to the mode of the other sex (i.e., according to the mode of the sex they identify as). According to mode of identifying sexuality of Finley and Austriaco, these people who received these potential surgeries would seem to have successfully become the other sex. Thus, it seems best to instead identify sex based on the clear teleology of the Y chromosome–which would ordinarily match most individuals’ sexual organs and psychology.7

The Y chromosome is trying to develop the fetus into a full adult, fertile male. At conception, and thus for the entire duration of the person’s life, this order exists in potency (first six weeks of gestation), is being actualized (until puberty or perhaps later), or is actualized (adulthood). If there is a DSD which prevents this order from being actualized, the order still exists and, as Fortin points out, the alternative sexual developmental path does not typically become actualized. And, as previously pointed out, the Thomist understanding of nature should not fundamentally change due to the exceptional cases—nature is always or for the most part.

5. Complete Androgen Insensitivity Syndrome

Complete Androgen Insensitivity Syndrome (hereafter CAIS) is a genetic condition where a person with XY chromosomes is completely immune to the effects of testosterone. Testosterone has no effect on their body. CAIS is a condition with genes other than the SRY gene. The SRY gene is normal in people with CAIS. The genetic issue in CAIS is in the AR gene (Androgen Receptor gene). AR provides directions for how to synthesize proteins called androgen receptors which allow the body to respond to androgens (i.e., male hormones, chiefly testosterone). In CAIS, there is a mutation in the AR gene which prevents androgen receptors from functioning properly and thus androgens from causing their normal effects on the body (Batista et al. 2018).

6. Identifying Sexuality

Recall that in normal sexual development, the ordinary developmental track is for female development in internal sex organs, external sex organs, and secondary sex features. In order for male development to occur, the SRY gene must activate and trigger the development of testes. Then, the androgens produced by the testes (mainly testosterone) cause the rest of the male development. Without the androgens the other sex features (external genitalia and secondary sex characteristics) will develop along the female path. Thus, persons with CAIS have male internal sex organs (testes) but since the androgens their testes produce have no effect on their body, they develop along the female path in all other ways. These people have XY chromosomes and testes within their bodies, but female genitalia, female secondary sex characteristics, and their brains develop more according to the female manner. Usually, people with CAIS are identified as female at birth (since they have female genitalia and secondary sex characteristics), and their condition is often not diagnosed for many years. They are infertile: they can neither get pregnant nor impregnate.

Note, since people with CAIS lack ovaries, they do not produce the normal amount of female hormones and thus the parts of their development which follows female tracks is still not quite the normal female path as they are deficient in female hormones.

CAIS is a difficult case because these people externally appear to be female and have more female-typical psychology since their brains were never masculinized by androgens. People with CAIS are often thought to be female and raised as girls until the age of puberty when their condition is finally diagnosed as a result of their failure to menstruate. Several Catholic authors identify people with CAIS as female (Buskmiller and Hruz 2022, pp. 81–83; Evert 2022, p. 62).

In contrast, I argue that the sex of a person must ultimately be determined by the teleological ordering of chromosome of the father’s sperm. If we determine sex based on genitalia (asserting that people with CAIS are female), then there seems to be no good reason why SRS cannot genuinely change one’s sex.8 The sexualization of one’s brain is clearly a secondary sex characteristic and cannot determine one’s sex. The type of sexual gamete one produces does not seem to be a valid determination either for several reasons.

First, females produce all their eggs while in utero while males do not begin producing sperm until puberty–yet each are male or female throughout their entire lives, and a castrated male remains a male (likewise a woman who had her ovaries removed remains a female). This means that one would have to say that the type of gamete one had the potency to produce or used to produce (because women do not produce eggs in an ongoing fashion and castrated males are still males despite not producing sperm) would determine one’s sex. But this would just put the biological determination back to the chromosomes which determine how the sexual gonads develop, into testes or ovaries, and thus which type of gamete one has the potency to produce. This would also apply to cases of DSD where the person produces neither type of sexual gamete.

Another alternative which some people choose, as seen, is to assert that we simply cannot know what sex some people are. This is an extremely unsatisfying answer and it seems an admission of defeat for these people’s positions about how to identify sexuality.

Thus, it seems the only alternative is that one’s sex is determined by the teleological ordering of chromosome of the sperm from one’s father. Thus, a person with CAIS is truly suffering from a great disability.9 They are males who failed to develop as a normal healthy male and instead developed, in most ways, along the female track.10

7. Catholic Transgenderism

In order to avoid great cruelty, it seems that a man with CAIS should be permitted to live as a female, to occupy a woman’s gender role. Since these persons look like women in every external way, have the psychological characteristics of women, and were likely raised as girls until puberty when their condition was first diagnosed as a result of a lack of menstruation, the appropriate way to live with this unique condition seems to assume (or continue) the gender role of a woman—to live and present oneself as a woman. The chief reason is that asking these people to assume the gender role of a man to match their sex seems both cruel and nearly impossible to achieve since they have the psychological characteristics of women. Thus, as a concession to their grave medical condition, these men with CAIS should be allowed to live as women. Part of this would include ordinarily using female pronouns to refer to them. Indeed, these people would not need to tell their friends about their condition.

Yet, a few key qualifications need to be made in this suggestion that men with CAIS live as women. First, it seems that these people are not eligible for Catholic marriage. This is not some cruel torture, just a recognition of the limits their medical condition includes. Clearly, they cannot be a husband since they cannot fulfill the marital act as a man which is a requirement for marriage (Canon 1993, #1084), and since they are not female, they could not be a bride. Thus, due to their unique medical condition, God calls these people to a life of celibacy. Second, although they are males, these persons cannot become priests. It would cause scandal by appearing to be a case of a woman-priest and the person, because they look like a woman, could not be a suitable icon of Christ. As the CDF cites Aquinas to say, “Sacramental signs represent by a natural resemblance” (Aquinas 2009, d. 25, q. 2, a. 2, qcla. 1, ad 4).11 The current Code of Canon Law includes this notion that a candidate for Holy Orders needs certain physical qualities when it says, “Only those are to be promoted to orders who… are endowed with integral morals and proven virtues and the other physical and psychic qualities in keeping with the order to be received” (Canon 1993, #1029). One physical quality in keeping with Holy Orders is being possessing a natural resemblance to Christ (i.e., clearly being male), but people with CAIS lack this.

In a way, I am proposing a Catholic transgenderism. I am proposing that men with CAIS live as the opposite gender, as women. Clearly this has nothing to do with the ordinary transgender question. Instead, this is an attempt to correctly identify the sex of people with CAIS and charitably help them bear their very unique cross. It could be compared to the unique lives and vocations of other people experiencing great disabilities. These persons have a great sexual disability, and thus their sexuality will be lived very differently from the norm.

8. Conclusions

The topic of how to identify the sex of persons with severe DSD is important for the Church because it concerns the eligibility of these people for certain sacraments (i.e., marriage and holy orders). While CAIS is a rare condition, with only 1 in 25.000 to 1 in 99.000 live births occurring each year (Batista et al. 2018, p. 228), the proper identification of sexuality matters tremendously to these people and matters for the coherence of the Catholic Church’s sacramental practice. Further, this Thomistic analysis provides a solid foundation concerning sexual difference (i.e., how does one determine which sex a person is) from which the Church can then engage contemporary issues surrounding more common transgender issues and questions of sexual difference. By following Aquinas’s key principle that sexual difference stems from the body, as well as teleology in nature, the identification of the sex of persons with CAIS becomes clear.