Aquinas on Sexual Sins – The Dangers of Speaking Formally

Which is worse: adultery or masturbation? Rape or masturbation? Did Aquinas teach that masturbation is a greater sin than rape, because masturbation is unnatural, and rape is not? If so, what did he mean by speaking in this? The suggestion that masturbation is ultimately a greater sin than adultery or rape is immediately repellent to us. In fact it is ridiculous, yet certain authors attribute precisely this position to Thomas Aquinas, reading him to be saying that the sin of masturbation is simply speaking, ultimately, worse than the sins of adultery and rape. Moreover, the further argument is made that the Church upheld this position for a long time, and this (false claim) is used to attack the Church's credibility in sexual ethics. Doubt is sometimes expressed regarding various teachings or practices of the Church, e.g., regarding the Church's affirmation that homosexual intercourse is wrong, or the restriction of priestly ordination in the Roman Rite to those who freely choose to embrace celibacy. The argument is made that if the Church "taught for a thousand years that masturbation is a worse sin than rape", its teaching on sexual matters can't be very sound.

This misunderstanding of the Church's traditional teaching on sins against nature seems to be more prevalent than I realized. I hadn't previously realized how many authors and teachers assert that not only many medieval theologians, but even Thomas Aquinas taught this. Here are some sample quotes from books discussing masturbation in Aquinas:

[In Aquinas's view], Because sins against nature were sins against God, they were considered more serious than sins against other people, such as adultery, seduction, and rape (John F. Schumaker, Religion and Mental Health [Oxford University Press US], 1992), 76).To make his point perfectly clear, Aquinas poses a question: are not rape and adultery worse than unnatural acts, since they harm other persons, while consensual sins against nature do not? The answer is unequivocal: the four non-procreative forms of sex are worse, since–though not harmful to others–they are sins directly against God himself as the creator of nature. According to this logic, rape, which may at least lead to pregnancy, becomes a less serious sin than masturbation (Louis Crompton, Homosexuality and Civilisation, [Harvard University Press, 2006], 188).

"A practice opposed to the pattern set for us by nature" exceeds in wickedness the seduction of an innocent of the opposite sex, adultery, and rape (II-II 154:12) (Sex from Plato to Paglia, by Alan Soble [Greenwood Publishing Group, 2006], 1053).

One unfamiliar with the scholastic manner of speaking formally about an issue, that is, addressing precisely the question at hand, might easily get this impression from Aquinas's treatment of sexual "sins against nature."

Here is the text itself. In the Summa Theologiae II-II, q. 154, a. 12, Aquinas says:

In each kind of thing the worst corruption is the corruption of the principle on which other things depend. Now the principles of reason are the things in accord in nature… and therefore, to act against what is determined by nature, is most serious and base. Therefore since in the sins against nature man transgress what is determined by nature in regard to sex, the sin in this matter is the gravest kind of sin. After this is incest… while by the other species of lust one transgresses only that which is determined according to right reason, but presupposing the natural principles. But it is more contrary to reason to have sex not only contrary to the good of the offspring to be born, but also with injury to another. And therefore simple fornication, which is committed without injury to another person, is the least kind of lust.

The first objection of the article argues that sins against nature are not the worst, because they are not the most contrary to charity: "The more a sin is contrary to charity the graver it is. Now adultery, seduction and rape, which are injurious to our neighbor, seem to be more contrary to the love of our neighbor, than unnatural sins, by which no other person is injured. Therefore sin against nature is not the greatest among the species of lust." St. Thomas replies to this objection: "As the order of right reason is from man, so the order of nature is from God himself. And therefore in sins against nature, in which the very order of nature is violated, injury is done to God himself, the one who ordains nature."

Aquinas is focusing on the sins precisely as a violation of the right use of sexuality, and abstracting from other aspects of them. As justice is a greater virtue than chastity, so injustice is a greater evil than unchastity, and thus all things considered, Aquinas would consider rape a greater evil than masturbation or contraception. This formal way of speaking is recognized by some more considerate authors:

The teaching of medieval theologians that such sexual sins as masturbation, sodomy, and contraception are more perverse, as sexual sins, than fornication or adultery or even rape (the former were said to be contra naturam whereas the latter were said to be praeter naturam), angers many people today. But this teaching must be understood properly. The medieval theologians are claiming that certain kinds of sexual sins more seriously offend the virtue of chastity than do others. They are not saying that these sins are for this reason less grave as sins than adultery or rape, for instance. After all, adultery and rape are very serious violations of the virtue of justice as well as being violations of the virtue of chastity. Thus, as a sin, rape is far more serious than masturbation or homosexual sodomy because it not only offends chastity but also gravely violates justice. (Ronald David Lawler, Joseph M. Boyle, William E. May, Catholic sexual ethics: a summary, explanation & defense).

It is important to understand this formal way of speaking, considering one aspect of human behavior and abstracting from other aspects. But as Aquinas himself says in another context, "where such a manner of speaking is found in the writings of an authority, one should not continue to speak in this manner, but should piously explain what is said" (Summa Theologiae I, q. 31, a. 4, loose translation).

In regards to the comparison between fornication and masturbation, St. Thomas may have in mind fornication in an instance where there is a potential marriage between the two persons (even if they are not engaged), since otherwise it would be contrary to the good of the offspring who might be born. Whether he had this in mind or not, it does seem to me that there are many cases where fornication is worse than masturbation, on account of the harm done to the other party, and on account of the potential harm of children conceived and born as a result (e.g., if they are thereby deprived of the presence of one parent in the home).

The Reception of Thomas Aquinas

I would agree that Thomas Aquinas's classification of sins as received by moralists in following centuries became a problem, in part because it was not used formally, but materially; that is, the descriptions of sins and the various gravity of different sins or aspects of sins were applied directly to physical, material acts. Even Alphonsus Liguori, named the patron of confessors and moralists by Pope Pius XII, seems to have fallen into this error. And in this respect I do see problems with the Church's usual approach to sexual morality for centuries, not sexual morality in particular however, but simply morality in general, the tendency being to take an extrinsic, legalistic approach to morality, and to focus on sins, rather than an approach focused on the real nature of human goods. This was to some extent an outgrowth of nominalism, which made of natural law a kind of arbitrary imposition by God's will. In another post I'll come back to this general topic of legalistic morality.


I gather from the questions that bring people to this post that this anachronistic reading of Thomas Aquinas (and the other scholastics) is a common one. Aside from some general queries such as "contra naturam in Aquinas," or "Aquinas' thoughts on rape," or "Aquinas on sexual morality," "Thomas Aquinas on masturbation," "Aquinas' views on rape," there are a number of questions that suggest having encountered such a view:

1. When did rape become worse than masturbation? (Related questions: Rape is not as bad as masturbation? Is masturbation a greater sin than rape? Masturbation worse than incest? Which is worse, masturbation or adultery?)

It was all along. But if the question is meant in the sense "when did people stop making technical lists of how fundamentally an act goes against the sexual purpose of the genital organs?", the answer is, "when they in general stopped making such technical lists."

2. Is masturbation worse than fornication? (Similar related queries: Is masturbation a greater sin than having sex? [This must mean "having sex" outside of a marital relationship.]; is masturbation better or worse than actual intercourse?)

In most cases not. First, as noted above, in the many cases where the present relationship or the capacity for a committed and unselfish relationship in the future is seriously harmed, or where danger to offspring is present, fornication is objectively graver. Moreover, masturbation requires, and in most cases involves, a much less deliberate act of will than fornication does, and therefore the sin is any case subjectively less bad.

3. The catholic church taught that masturbation is worse than rape because at least the latter might result in conception. (Related questions: Rape is much less a sin than masturbation. Masturbation is worse than rape? [Did] Aquinas [teach that] rape is better than masturbation?)

No, it didn't.

4. Is masturbation worse than adultery?


Send Forth Thy Spirit

Send forth thy Spirit, O Lord, and renew the face of the earth!

Homily of Pope Benedict for the Solemnity of Pentecost (Italian text at the Vatican website)

Dear Brothers and Sisters!

Every time we celebrate the Eucharist, we live in faith the mystery that is accomplished on the altar, that is, we participate in the supreme act of love that Christ realized with his death and resurrection. The unique center of the liturgy and of Christian life — the paschal mystery — then assumes, on different solemnities and feasts, specific "forms," with further meanings and particular gifts of grace. Among all the solemnities, Pentecost is distinguished by its importance, because in it that which Jesus himself proclaimed as the purpose of his whole mission on earth is accomplished. In fact, while he was going up to Jerusalem, he declared to the disciples: "I have come to cast fire on the earth, and how I wish that it were already kindled!" (Luke 12:49). These words find their most obvious realization 50 days after the resurrection, on Pentecost, the ancient Hebrew feast that, in the Church, has become the feast of the Holy Spirit par excellence: "There appeared to them parted tongues as of fire … and all were filled with the Holy Spirit" (Acts 2:3-4). The Holy Spirit, the true fire, was brought to earth by Christ. He did not steal it from the gods — as Prometheus did according to the Greek myth — but he became the mediator of the "gift of God," obtaining it for us with the greatest act of love in history: his death on the cross.

God wants to give this "fire" to every human generation, and naturally he is free to do this as and when he wants. He is spirit, and the spirit "blows where it wills" (cf. John 3:8). However, there is an "ordinary way" that God himself has chosen for "casting fire upon the earth": this way is Jesus, the incarnate only begotten Son of God, who died and is risen. For his part, Jesus Christ established the Church as his mystical body, so that it might prolong his mission in history. "Receive the Holy Spirit" — the Lord says to the Apostles on the evening of his resurrection, accompanying those words with an expressive gesture: he "breathed" on them (cf. John 20:22). Thus he showed that he was giving them his Spirit, the Spirit of the Father and of the Son.

Now, dear brothers and sisters, in today's solemnity Scripture tells us how the community must be, how we must be to receive the Holy Spirit. In the account that describes the event of Pentecost, the sacred author writes that the disciples "were together in the same place." This "place" is the Cenacle, the "upper room," where Jesus had held the Last Supper with his disciples, where he appeared to them, after having risen from the dead; that room that had become the "seat," so to speak, of the nascent Church (cf. Acts 1:13). Yet the Acts of the Apostles intends more to indicate the interior attitude of the disciples than to insist on a physical place: "They all persevered in concord and prayer" (Acts 1:14). So, the concord of the disciples is the condition for the coming of the Holy Spirit; and presupposed to concord is prayer.

Dear brothers and sisters, this is also true for the Church of today. It is true for us who are gathered here together. If we do not want Pentecost to be reduced to a simple ritual or to a suggestive commemoration, but that it be a real event of present salvation, we must predispose ourselves, through a humble and silent listening to God's Word, to God's gift in religious openness. In order that Pentecost may renew itself in our time, perhaps there is need — without taking anything away from God's freedom — for the Church to be less "preoccupied" with activity and more dedicated to prayer. Mary Most Holy, the Mother of the Church and Bride of the Holy Spirit, teaches us this. This year Pentecost occurs on the last day of May, when the Feast of the Visitation is customarily celebrated. This event was also a kind of little "Pentecost," which brought forth joy and praise from the hearts of Elizabeth and Mary — the one barren and the other a virgin — who both became mothers by an extraordinary divine intervention (cf. Luke 1:41-45).

The music and singing that is accompanying our liturgy, also help us to be united in prayer, and in this regard I express a lively acknowledgment to the choir of the Cologne cathedral and the Cologne Chamber Orchestra. Joseph Haydn's "Harmoniemesse," the last of the Masses composed by this great musician, and a sublime symphony for the glory of God, was chosen for today's Mass. The Haydn Mass was a fitting choice given that it is the bicentennial of the composer's death. I address a cordial greeting to all those who have come for this.

To indicate the Holy Spirit, in the account of Pentecost in the Acts of the Apostles, two great images are used: the image of the tempest and the image of fire. Clearly, St. Luke had in mind the theophany of Sinai, recounted in Exodus (19:16-19) and Deuteronomy (4:10-12:36). In the ancient world the tempest was seen as a sign of divine power, in whose presence man felt subjugated and terrified. But I would like to highlight another aspect: the tempest is described as a "driving wind," and this brings to mind the air that distinguishes our planet from others and permits us to live on it. What air is for biological life, the Holy Spirit is for the spiritual life; and as there is air pollution, which poisons the environment and living things, so there is a pollution of the heart and the spirit, which mortifies and poisons spiritual existence. In the same way that we should not be complacent about the poisons in the air — and for this reason ecological efforts are a priority today — we should also not be complacent about that which corrupts the spirit. But instead it seems that our minds and hearts are menaced by many pollutants that circulate in society today — the images, for example, that make pleasure a spectacle, violence that degrades men and women — and people seem to habituate themselves to this without any problem. This is said to be freedom, without recognizing that all this pollutes, poisons the soul, above all the soul of the new generations, and ends up limiting freedom itself. The metaphor of the driving wind of Pentecost makes one think of how precious it is to breathe clean air, whether it be physical air with our lungs, or spiritual air — the healthy air of the spirit that is love — with our heart.

The other image of the Holy Spirit that we find in the Acts of the Apostles is that of fire. At the beginning I compared Jesus with the mythological figure of Prometheus. The figure of Prometheus suggests a characteristic aspect of modern man. Taking control of the energies of the cosmos — "fire" — today human beings seem to claim themselves as gods and want to transform the world excluding, putting aside or simply rejecting the Creator of the universe. Man no longer wants to be the image of God but the image of himself; he declares himself autonomous, free, adult. Obviously that reveals an inauthentic relationship with God, the consequence of a false image that has been constructed of him, like the prodigal son in the Gospel parable who thought that he could find himself by distancing himself from the house of his father. In the hands of man in this condition, "fire" and its enormous possibilities become dangerous: they can destroy life and humanity itself, as history unfortunately shows. The tragedies of Hiroshima and Nagasaki, in which atomic energy, used as a weapon, ended up bringing death in unheard of proportions, remain a perennial warning.

We could of course find many examples, less grave and yet just as symptomatic, in the reality of everyday life. Sacred Scripture reveals that the energy that has the ability to move the world is not an anonymous and blind power, but the action of the "spirit of God that broods over the waters" (Genesis 1:2) at the beginning of creation. And Jesus Christ "cast upon the earth" not a native power that was already present but the Holy Spirit, that is, the love of God, who "renews the face of the earth," purifying it of evil and liberating it from the dominion of death (cf. Psalm 103 [104]: 29-30). This pure "fire," essential and personal, the fire of love, descended upon the Apostles, gathered together with Mary in prayer in the cenacle, to make the Church the extension of Christ's work of renewal.

Finally, a last thought also taken from the Acts of the Apostles: the Holy Spirit overcomes fear. We know that the disciples fled to the cenacle after the Master's arrest and remained there out of fear of suffering the same fate. After Jesus' resurrection this fear did not suddenly disappear. But when the Holy Spirit descended upon them at Pentecost, those men went out without fear and began to proclaim the good news of Christ crucified and risen. They had no fear, because they felt that they were in stronger hands. Yes, dear brothers and sisters, where the Spirit of God enters, he chases out fear; he makes us know and feel that we are in the hands of an Omnipotence of love: whatever happens, his infinite love will not abandon us. The witness of the martyrs, the courage of the confessors, the intrepid élan of missionaries, the frankness of preachers, the example of all the saints — some who were even adolescents and children — demonstrate this. It is also demonstrated by the very existence of the Church, which, despite the limits and faults of men, continues to sail across the ocean of history, driven by the breath of God and animated by his purifying fire. With this faith and this joyous hope we repeat today, through Mary's intercession: "Send forth thy Spirit, O Lord, and renew the face of the earth!"