Did Thomas Aquinas write anything about hermaphrodites? I have not been able to find his opinions on the matter.

  • Hermaphroditism occurs today in about 0.0012% of births. Many of these require modern medicine to diagnose. 750 years ago they would be even less detectable, and would tend to be hidden if possible. Saying that its incidence was 1 in 100,000 would be generous. The condition would be very rare, and even if Aquinas had encountered it, it would likely have been lumped in with the many, much more common, other forms of physical birth defects. They would probably not have been noticed as anything special, not worth writing about, certainly not by a philosopher and theologian. Apr 17, 2022 at 23:51
  • @RayButterworth St. Thomas certainly knew about offspring with birth defects.
    – Geremia
    Apr 18, 2022 at 4:21
  • @Geremia, yes, but the rarity of this one specific condition makes it very unlikely he'd single it out from among the many other types of "monster" (which, as I type this, I now notice that that is the generalized approach you took in your own answer). Apr 18, 2022 at 13:38

2 Answers 2


The closest St. Thomas comes to discussing androgynous or hermaphroditic individuals seems to be Summa Theologica I q. 93 a. 4 (Whether the image of God is found in every human?) ad 1:

after the words, "To the image of God He created him," it is added, "Male and female He created them" (Gn. 1:27). Moreover it is said "them" in the plural, as Augustine (Gen. ad lit. iii, 22) remarks, lest it should be thought that both sexes were united in one individual.

Gen. I, cum dixisset, ad imaginem Dei creavit illum, scilicet hominem, subdidit, masculum et feminam creavit eos, et dixit pluraliter eos, ut Augustinus dicit, ne intelligatur in uno individuo uterque sexus fuisse coniunctus.

A hermaphrodite is "both sexes" "united in one individual".

The words hermaphroditus, gynandria, and androgynia* do not appear in St. Thomas's works, but he does discuss monstra ("monsters") 79×.

*cf. these terms in the 1917 Code of Canon Law

A monstrum is an offspring with a birth defect; Summa Theologica II-II q. 51 a. 4 c.:

monstrous births of animals are beside the order of the active seminal force, and yet they come under the order of a higher principle, namely, of a heavenly body, or higher still, of Divine Providence.

monstruosi partus animalium sunt præter ordinem virtutis activæ in semine, tamen cadunt sub ordine altioris principii, scilicet cælestis corporis, vel ulterius providentiæ divinæ.

Note also: St. Thomas opposes Origen's theory that humans were androgynous before the Fall, that male and female genitalia were added in view of or after Adam's sin. See Summa Theologica suppl. q. 80 a. 1 "Whether all the members (parts) of the human body will rise again?"; St. Thomas shows the male and female genitalia are part of human nature, even before the Fall.


"This can be made clear if we observe the mode of generation carried out in various living things. Some living things do not possess in themselves the power of generation, but are generated by some other specific agent, such as some plants and animals by the influence of the heavenly bodies, from some fitting matter and not from seed: others possess the active and passive generative power together; as we see in plants which are generated from seed; for the noblest vital function in plants is generation. Wherefore we observe that in these the active power of generation invariably accompanies the passive power. Among perfect animals the active power of generation belongs to the male sex, and the passive power to the female. And as among animals there is a vital operation nobler than generation, to which their life is principally directed; therefore the male sex is not found in continual union with the female in perfect animals, but only at the time of coition; so that we may consider that by this means the male and female are one, as in plants they are always united; although in some cases one of them preponderates, and in some the other."


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