a. Double Proof of the First Main Conclusion

α. First Proof

12. For proof of the first conclusion [n.7] let this be the first prior conclusion: that man want to procreate offspring in the human species is an act capable of being circumstanced with the right circumstances. And the proof is that the act is not per se evil such that it be incapable of being rightly circumstanced (such as is ‘to give what is another’s’).

13. This is plain:

First because it is not more contrary to right reason or inclination of nature that man preserves his species than that any other animals save their own; indeed, it is the more according to inclination the more this species is more perfect; but this species cannot as a rule be preserved save through offspring.

Next second because, although man was to be immortal yet it was to belong to him, according to the right inclination of nature, to communicate his species in the way in which it was to be possible for him, that is, by propagating.

Next third, from matters of belief, because a precept is not given about anything illicit, but in Genesis 1.28 before the Fall, and in Genesis 9.7 to Noah and his sons after the Fall, a precept is given about propagation: “Increase and multiply.”

Next fourth because, according to right reason resting on faith, it is not evil but honorable to act, according to divine predestination, for the repair of angelic ruin and of the heavenly city Jerusalem; but the elect, predestined for the repair of that ruin, are not commonly produced save by propagation;     therefore etc     .

14. So therefore does it appear that the act is not of itself evil; therefore, it is either of itself good or is capable of being well circumstanced.

15. But that it is not of itself sufficiently good with moral goodness the proof is that no ‘to will’ is of itself good from the fact that it focuses on an object morally good, unless it focus on an object that is in itself something to will, that is, that is simply the ultimate good. This ‘to will’ is to love God, where it cannot be against right reason, rather it is necessarily according to right reason, that such act tend to such object. But this is because this object is the ultimate end to be willed according to itself by anyone ordered to an end in the way of being able to love that end. For a man can rightly or not rightly make a distinction about everything that is for the end, because he can do so either by ordering it to God and thus use it, or by not ordering it and so enjoy it, which is a great sin.

16. But the good on which focuses this act (which is procreation or wanting to procreate offspring) is plainly not the ultimate end but only something ordered or orderable to the ultimate end; therefore such an act is not of itself sufficiently good morally; therefore it is capable of being well circumstanced [sc. so as to be morally good].

17. Again, both facts, namely that this act is not of itself good and not morally bad, can be proved by one argument: because only that act is of itself bad whose object it is repugnant to that the act is good, or whose object is repugnant to the goodness of the act, or which act is repugnant to the agent according to natural right reason; and, by arguing through the opposite, only that act is of itself good whose object necessarily agrees with the agent’s act according to right reason; therefore, this act is neither of itself good nor of itself bad. For no act is good of its kind, or from its object alone, save loving God, which act has its goodness from the object alone; nor is any act bad of its kind, or from its object alone, save hating God. Hence neither of these acts is it necessary to specify or to circumstance; nor is either capable of being circumstanced. For God cannot be too much loved (understanding this of the love of friendship) nor can anyone hate God well.

18. This therefore is the first conclusion, that to will to procreate offspring is an act capable of being circumstanced with the right circumstances [= the first preceding conclusion, n.12].

β. Second Proof

19. The second conclusion [sc. the second prior conclusion, n.12] is that the first circumstance required for the moral goodness of this act is the circumstance of the end, as is universally the case in morals. And there is this circumstance in the proposition at issue: to will to procreate offspring to be religiously educated for the increasing of divine cult.

20. This is proved by reason, because perfect human operation is the end of man, Ethics 1.9-10.1099a7-9b28, 10.1.1174b18-5a1. Therefore, for this end should anyone want to have offspring.

21. This is also proved from matters of belief, because anyone should love his neighbor from charity as he loves himself, that is, for the same thing; but anyone should love himself for honest conversation and divine cult; therefore he should thus love his neighbor, and especially the offspring to whom he is especially bound.

22. This is confirmed by Augustine [in fact Lombard, Sent. IV d.31 ch.2 n.4, though they are quoted as Augustine’s by Richard of Middleton], “Not everyone,” he says, “who has offspring has the good of offspring, because the good of offspring is not said to be the offspring itself, but the hope or desire whereby offspring are sought for this, that they be religiously formed.”

23. But this circumstance does not suffice, although it is first and leads to all the others. And therefore a second circumstance follows, namely that this act ought to be between determinate persons, male and female. That it should be between male and female, this is not a circumstance but is necessarily included in the act that is the procreating of offspring; but that it be between determinate persons, this is one of the circumstances on the part of the agent causes that are due and fitting for this end - and this not only as to procreation of offspring but also as to repeated procreation of offspring (and I say ‘repeated’, because it is fitting for one man to have determinately one wife not only for procreation but also for repeated procreation, for that anyone would come together with anyone, this nature does not suffer, and in the beasts too it is not found). But that one man should be determinately of one woman is plain, for indiscriminate conjunction would be against the good of offspring (which is the end here intended), and against the good of the family, and against the good of the city.

24. The proof of the first [n.23]: because offspring would be not religiously educated on the part of parents as parents would not have determinate knowledge of their offspring - at least the father, and so he would not be solicitous about bestowing due discipline on his offspring; nor conversely would offspring bestow on the father obedience or due reverence and filial fear, and it is because of this filial fear that a son obeys the father more, and can be more easily disciplined by him than by another.

25. The second [n.23] too is proved, because the good of the family consists in a firm adhesion of the chief persons of the family; otherwise the whole thing is indiscriminate (and for this reason the Philosopher says Ethics 8.14.1162a17-19 that man is naturally a conjugal animal because a domestic animal), and neither would some persons apply diligence to the things mutually necessary for themselves or their offspring.

26. The third point [23], that it is against the good of the city, is plain, because by matrimonial contracts of this sort is friendship preserved in cities; therefore it is necessary that contracts of this sort exist between certain persons, because the friendship of citizens arises, for the most part, from determinate closeness in a definite rank. But, given this [sc. indiscriminate conjunction], there would be no known certain closeness that would be the cause of friendship; rather all closeness would be confused.

27. And therefore rightly does Aristotle criticize Socrates’ polity, Politics 2.1-2.1261a4-12, who wanted all wives to be common, because for the state of fallen nature much better is the polity he himself ordains, namely that determinate persons have determinate wives. And the indiscriminate union of male with female would be against reason for every state [of nature].

28. This circumstance too appears from things believed from Sacred Scripture, because in Genesis 2.24 it is said that “they will be two in one flesh,” and Christ sets down the same in Matthew 19.5 and St. Paul in I Corinthians 7.2, “Let each have his own wife,” supply, “on account of fornication.” And let it be that this determination is not by natural reason proved to be simply necessary in such way that its opposite would be repugnant to natural and manifest reason - at least this affirmative is sufficiently plain, that it is honorable that the persons of the Church are, for this act, determinate to each other.

29. But another circumstance, that it is honorable for those persons to be obligated to each other with an indissoluble bond for this end, is proved from the preceding one, that just as determination of persons avails for the due education of offspring and for the good of the family and the city, so too does the perpetual adhesion of determinate persons to each other avail for this same thing. And they would, because of the many occasions and difficulties that arise, not perpetually adhere to each other unless they were obligated by such an indissoluble bond to such adherence to each other.

30. And let it be that this conclusion, which is the main one in this article, could not be proved by evidently natural reason to be simply necessary; it is proved the way it is proposed, that it is honorable and consonant with natural reason for male and female to be thus obligated together for such an end.

31. From this is plain the solution to a question, namely whether such obligation belongs to the law of nature; for it was said above, in distinction 17 n.19, that most properly belonging to the law of nature is a per se known practical principle and a conclusion demonstratively following from such a principle; but belonging secondarily to the law of nature is a truth evidently consonant with such principles and conclusions, though not necessarily following from them. And in this way belongs to the law of nature that it is honorable for male and female to be obligated to the aforesaid end.