Commentaria in Summam contra Gentiles, Liber III

The second condition of marriage ¹ is that it be of one man to one woman. Now, although this conclusion was touched upon to some extent in the preceding chapter, ² yet because it was not proved there, but rather presupposed, St. Thomas therefore proves it in this place.

1. First, he argues as follows. Every animal desires to enjoy freely the pleasure of intercourse, just as also the pleasure of food. But this freedom is hindered by the fact that several access one, or vice versa. Therefore, it proceeds from natural instinct that one woman belongs to one man.

The minor premise is explained both from the freedom of enjoying food, which is hindered if another animal usurps the food that one animal desires to take; and by this sign: that animals fight similarly on account of food and on account of intercourse.

II. Secondly: and this is a special reason in human beings. Man naturally desires to be certain of his offspring. But this certainty would be entirely taken away if several men belonged to one woman. Therefore, etc.

Moreover, St. Thomas adds that there is a difference with respect to several not belonging to one. For toward the fact that one female is not known by several males, both of the stated reasons concur; but as to the fact that one male does not know several females, only the first reason concurs, and not the second. For certainty of offspring is not taken away on this account; but the freedom of using the husband is indeed taken away from the female, which the first reason touched upon.

From which it is inferred that, because certainty of offspring is the principal good sought from marriage, no human law or custom has permitted that one woman be the wife of several. Hence this was also regarded as unfitting among the ancient Romans, as Valerius witnesses.

2. Concerning what is said—that certainty of offspring is the principal good sought from marriage—it should be noted that this is not said as though the principal end of marriage, taken absolutely, were certainty of offspring, for certainty of offspring is not the principal end, but rather the generation and education of offspring; but because without it there cannot be the education of offspring, which is the principal end of marriage together with procreation. Hence, when it is said to be the principal good of marriage, it must be understood not as its principal end, but as necessarily accompanying the principal end.

3. It must also be observed, from the teaching of St. Thomas in IV Sent., d. 33, q. 1, a. 1, ad 7, ³ that for one man to have several wives is not against the primary precepts of nature, but against the secondary ones, which are derived from the primary: because it neither totally takes away nor in any way hinders the primary end that nature intends from marriage, namely the procreation of offspring and their education; since one man suffices for making several wives fruitful and for educating the children born of them. But it indeed greatly hinders the secondary end, which is the mutual sharing of the tasks that are necessary in life, because there cannot easily be peace in a household where several wives are joined to one husband. But for one wife to have several husbands is against the primary precepts of the law of nature. For in one respect the good of the offspring is taken away entirely: namely, as to its education, which is removed through the uncertainty of the offspring with respect to the father. But in another respect it is hindered, namely as to procreation: because if a woman, after a first impregnation, is impregnated again by another, it can scarcely happen without corruption occurring with respect to both fetuses or with respect to one of them.

Therefore, because reason is not so obscured concerning the primary precepts of the law of nature, which are like common conceptions in speculative matters, ⁴ as it is concerning its secondary precepts; for that reason, although some human law or custom among some peoples has obtained that one man could have several wives, yet by no law or custom, as is said here, has it been permitted that one woman have several husbands.

III. Thirdly. Among all animals, the male has the greatest care for offspring in the human species. Therefore, it is natural to man that one male have one female, and vice versa. — The consequence is proved: because in every animal species in which the father has care for offspring, one male has only one female. For one male would not suffice to provide help in the education of offspring to several females.

2. Concerning this last statement, it must be observed that this is true only in males of a different species from man; for concerning man it has been said, ⁵ according to the mind of St. Thomas, that one suffices for educating the children of several wives. But then it seems that the argument concludes nothing about man. For the consequence would be denied; and it would be said in response to the proof that, if in other animals in which there is solicitude for offspring in the father, one male has only one female, it is not necessary that this also be the case in man. And the reason for this is that in other animals one male does not suffice for educating the children of several, but in man he does suffice.

He answers that this argument proceeds from a certain similitude. For just as the solicitude that is in the father for the offspring is the reason for other animals that one female belongs to one male, so also in human beings. But that one belong to one is for the former according to the primary inclination of nature, because otherwise offspring could not be educated, which is the primary good intended by nature. But in man it is from the secondary inclination of nature: because from solicitude for offspring it proceeds by natural instinct that husband and wife remain together, and consequently that they communicate with one another in the necessary tasks of life; which would not fittingly occur if one man had several wives, because peace in the household would be hindered.

Hence St. Thomas intends to argue thus. Just as, when animals are naturally inclined to the conjunction of male and female, nature's primary intention is toward the education of offspring; so by nature's secondary intention, proceeding from that primary one, man is inclined to the mutual sharing of the tasks of life between male and female. But other animals, because from a plurality of females for one male the education of offspring would be hindered, have it from nature primarily that one male have only one female. Therefore, since the said sharing of the tasks of life is also hindered by a plurality of wives for one man, it is from the secondary instinct of nature that one man have only one wife; and also conversely that one woman have one husband, because peace in the household would also, and much more, be taken away if one woman belonged to several men.

IV. Fourthly. If it were not lawful for a woman to have several husbands, but it were lawful for a man to have several wives, the friendship of the wife toward the husband would not be free, but servile, as it were. But this is unfitting. Therefore, etc. — The consequence is proved: both by reason, because friendship consists in a kind of equality; and by experience, because among men who have several wives, the wives are held like handmaids.

It must be noted that the proof of the consequence tends to this: that just as the husband is related to the wife in friendship, so also the wife is related to the husband, the same proportion being preserved, because friendship consists in a kind of equality, namely of proportion. But since the wife cannot have several husbands, if the husband has several wives, the husband seems to relate to them as to handmaids and entirely subject persons. Therefore their love toward the husband will also be servile, not free.

Fifthly: and this is a confirmation of the preceding reason. Intense friendship is not had toward many, as is clear from Ethics VIII. Therefore, if the wife has only one husband, but the husband has several wives, the friendship will not be equal on both sides. Therefore it will not be free, but servile, as it were: namely because the wife will love the husband intensely, but the husband will not love the wife intensely.

Sixthly. It is contrary to good morals that one man have several wives. Therefore, etc. — The consequence is proved: because marriage in human beings ought to be ordered according to what pertains to good morals. — And the antecedent is proved: because from this there follows discord in the household, as is clear from experience.

To this Durandus says, in Capreolus, Fourth Book, d. 33, ⁶ that it has no force, because it is accidental that there is not peace where there are several wives, namely from the fact that they are sometimes contentious. — But he does not see that, although in some cases a plurality of wives may sometimes be compatible with peace, nevertheless, for the state of fallen nature, it hinders it for the most part, since it gives rise to jealousy and many other disadvantages. Now art and law consider not only those things that are per se and necessary, but also those that happen for the most part.

The conclusion is confirmed by the authority of Genesis 2.

V. By this, indeed, the custom of those having several wives is excluded; and the opinion of Plato positing that wives ought to be common; and also of Nicholas, who was one of the seven deacons.

But concerning this a doubt occurs. For it seems to contradict what was said above, ⁷ where it was said that no human law or custom has permitted that one woman be the wife of several. For if Plato willed wives to be common, it is established that he willed one woman to belong to several.

He answers that the opinion of Plato that is reported here is taken not according to the truth, but according to what Aristotle imputes to Plato in Politics II. ⁸ For as St. Thomas says in IV De Regimine Principum, ⁹ since Socrates and Plato were devoted to virtues above all philosophers, it does not seem credible that they instituted such a community as Aristotle imputes to them, namely that women should be common to all as to intercourse: because this is more bestial than human. But they willed wives to be common to all as to the affection of love and mutual affection, but not as to intercourse.

Nicholas the Deacon, however, posited that not because he judged it to be good in that way, but relying on the authority of Plato, whom he thought, from Aristotle's report, to have willed wives to be common as to intercourse.

VI. Against the aforesaid conclusion one can argue in multiple ways. First. When a secondary end prejudices a principal end, the secondary end is to be neglected for the sake of the principal one. But sometimes peaceful dwelling with one wife prejudices generation, which is the principal end, because that wife is barren. Therefore, etc.

Secondly. It is lawful with cause to renounce one's right no less in part than in whole. But by the fact that a husband emits a vow of chastity, the other is prejudiced in whole; whereas by the fact that marriage is contracted with a second, it is prejudiced only in part. Therefore, if by the wife's permission and her consent it is lawful for the husband to emit a vow of chastity, by parity of reasoning, on account of the wife's barrenness, with the permission of the first wife, it is lawful to take a second.

Thirdly. The Pope can dispense in a solemn vow of continence on account of lack of an heir. Therefore he will be able to dispense so that a prince who has a barren wife may, while she is living, take another.

VII. For the evidence of this, it must be considered that, since having several wives is against the secondary precepts of nature, it belongs to him alone to remove this precept and to dispense in this who is the author of nature, and who gave such an inclination and such precepts to nature: for it belongs to him to dissolve a law to whom it belongs to establish it. And therefore, since God alone is the author of nature, he himself can dispense in this, and this dispensation belongs to him alone; but not to any other, except by divine commission.

Nor does it stand against this that dispensation can be given in vows, the fulfillment of which is nonetheless of divine and natural law. For when a prelate dispenses in a vow, he does not dispense in a precept of natural or divine law, as St. Thomas says in II-II, q. 88, a. 10, ¹⁰ but he determines that in some case that is not suitable matter of a vow which previously was suitable matter. And therefore neither by one's own authority, nor by the authority of any man, can anyone have several wives at the same time.

2. To the first, therefore, it is said that the major premise is false if it is understood that the secondary end is to be neglected by anyone on his own authority. But if it is understood that it is to be neglected by divine dispensation, it is conceded. And by the same reasoning, it is conceded that by divine authority someone could have several wives.

To the second it is said, first, that not only is it from this that one man cannot have several wives—namely that one woman has full right over the husband—but because this is against the precepts of natural and divine law, against which no one, without divine dispensation, can lawfully act. And therefore, however much one wife may wish to renounce the jurisdiction that she has over the husband's body, there remains nonetheless the precept of nature, against which it is lawful for no one to act.

It is said, secondly, that it is not similar concerning a vow of continence made by permission of the wife, and concerning the taking of another wife. For just as it is not repugnant to the law of nature that some particular human being not contract marriage, so it is not repugnant that he abstain from the marital act by permission of the wife. But to have another wife besides the first is repugnant to the law of nature impressed upon the human mind. Therefore the husband, with the wife consenting, can vow chastity, but not have several wives.

To the third it is said, first, that the assumption, according to St. Thomas, is false: as is clear in II-II, q. 88, a. 11; although in IV Sent., d. 38, q. 1, a. 4, ¹¹ he was of another opinion.

It is said, secondly, that granting that point, the intended conclusion still does not follow. Because, as was said above, in a dispensation of a vow there is no dispensation in a precept of natural or divine law, but it is only declared that in such a case that is not suitable matter of a vow. But in a dispensation for several wives, an action would be taken against natural law and divine law.

3. Aureolus makes other arguments by which he proves that having several wives is against the primary precepts of nature, and that in no way can dispensation fall there, even from God. See in Capreolus, in the place cited. ¹²