[Footnote 4: De Reg. Prin., iii. 9. This is one of the chapters the authorship of which is disputed.]
St. Thomas was therefore willing to endorse the argument of St. Augustine that slavery was a result of sin; but he also admits the justice of Aristotle's reasoning on the subject. In the section of the Summa where the question is discussed, whether the law of nations is the same as the natural law, one of the objections to be met is that 'Slavery among men is natural, for some are naturally slaves according to the philosopher. Now "slavery belongs to the law of nations," as Isidore states. Therefore the right of nations is a natural right.'[1] In answer to this objection St. Thomas draws the distinction between what is natural absolutely, and what is natural secundum quid, the passage which we have quoted in treating of property rights.[2] He then goes on to apply this distinction to the case of slavery. 'Considered absolutely, the fact that this particular man should be a slave rather than another man, is based, not on natural reason, but on some resultant utility, in that it is useful to this man to be ruled by a wise man, and to the latter to be helped by the former, as the philosopher states. Wherefore slavery which belongs to the law of nations is natural in the second way, but not in the first.'[3] It will be noted from this passage that St. Thomas partly admits, though not entirely, the opinion of Aristotle. In the De Regimine Principum he goes much further in the direction of adopting the full Aristotelian theory: 'Nature decrees that there should be grades in men as in other things. We see this in the elements, a superior and an inferior; we see in every mixture that some one element predominates…. For we see this also in the relation of the body and the mind, and in the powers of the mind compared with one another; because some are ordained towards ordering and moving, such as the understanding and the will; others to serving. So should it be among men; and thus it is proved that some are slaves according to nature. Some lack reason through some defect of nature; and such ought to be subjected to servile works because they cannot use their reason, and this is called the natural law.'[4] In the same chapter the right of conquerors to enslave their conquered is referred to without comment, and therefore implicitly approved by the author.
[Footnote 1: II. ii. 57, 3.]
[Footnote 2: Supra, p. 64.]
[Footnote 3: II. ii 57, ad. 2.]
[Footnote 4: De Reg. Prin., ii. 10.]
'Thus,' according to Janet, 'St. Thomas admits slavery as far as one can admit it, and for all the reasons for which one can admit it. He admits with Aristotle that there is a natural slavery; with St. Augustine that slavery is the result of sin; with the jurisconsult that slavery is the result of war and convention.'[1] 'The author justifies slavery,' says Franck, 'in the name of St. Augustine, and in that of Aristotle; in the name of the latter by showing that there are two races of men, one born to command, and the other to obey; in the name of the former in affirming that slavery had its origin in original sin; that by sin man has forfeited his right to liberty. Further, we must admit slavery as an institution not only of nature and one of the consequences of the fall, we must admit a third principle of slavery which appears to St. Thomas as legitimate as the other two. War is necessary; therefore it is just; and if it is just we must accept its consequences. One of these consequences is the absolute right of the conqueror over the life, person, and goods of the conquered.'[2]
[Footnote 1: Op. cit., vol. i. p. 431.]
[Footnote 2: Franck, op cit., p. 69.]
Aquinas returns to the question of slavery in another passage, which is interesting as showing that he continued to make use of the analogy between slavery and property which we have seen in the Fathers. 'A thing is said to belong to the natural law in two ways. First, because nature inclines thereto, e.g. that one should not do harm to another. Secondly, because nature did not bring in the contrary; thus we might say that for man to be naked is of the natural law because nature did not give him clothes, but art invented them. In this sense the possession of all things in common and universal freedom is said to be of the natural law, because, to wit, the distinction of possession and slavery were not brought in by nature, but devised by human reason for the benefit of human life. Accordingly, the law of nature was not changed in this respect, but by addition.'[1]