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Ethical Aspect of Slavery

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In Greek and Roman civilization slavery on an extensive scale formed an essential element of the social structure; and consequently the ethical speculators, no less than the practical statesmen, regarded it as a just and indispensable institution. The Greek, however, assumed that the slave population should be recruited normally only from the barbarian or lower races.

The Roman laws in the heyday of the empire, treated the slave as a mere chattel. The master possessed over him the power of life and death; the slave could not contract a legal marriage, or any other kind of contract; in fact he possessed no civil rights; in the eyes of the law he was not a "person". Nevertheless the settlement of natural justice asserted itself sufficiently to condemn, or at least to disapprove, the conduct of masters who treated their slaves with signal inhumanity.

Christianity found slavery in possession throughout the Roman world; and when Christianity obtained power it could not and did not attempt summarily to abolish the institution. From the beginning, however, as is shown elsewhere in this article, the Church exerted a steady powerful pressure for the immediate amelioration of the condition of the individual slave, and for the ultimate abolition of a system which, even in its mildest form, could with difficulty be reconciled with the spirit of the Gospel and the doctrine that all men are brothers in that Divine sonship which knows no distinction of bond and free. From the beginning the Christian moralist did not condemn slavery as in se, or essentially, against the natural law or natural justice. The fact that slavery, tempered with many humane restrictions, was permitted under the Mosaic law would have sufficed to prevent the institution form being condemned by Christian teachers as absolutely immoral. They, following the example of St. Paul, implicitly accept slavery as not in itself incompatible with the Christian Law. The apostle counsels slaves to obey their masters, and to bear with their condition patiently. This estimate of slavery continued to prevail till it became fixed in the systematized ethical teaching of the schools; and so it remained without any conspicuous modification till towards the end of the eighteenth century. We may take as representative de Lugo's statement of the chief argument offered in proof of the thesis that slavery, apart from all abuses, is not in itself contrary to the natural law.

Slavery consists in this, that a man is obliged, for his whole life, to devote his labour and services to a master. Now as anybody may justly bind himself, for the sake of some anticipated reward, to give his entire services to a master for a year, and he would in justice be bound to fulfil this contract, why may not he bind himself in like manner for a longer period, even for his entire lifetime, an obligation which would constitute slavery? (De Justitia et Jure, disp. VI, sec. 2. no. 14.)

It must be observed that the defence of what may be termed theoretical slavery was by no means intended to be a justification of slavery as it existed historically, with all its attendant, and almost inevitably attendant, abuses, disregarding the natural rights of the slave and entailing pernicious consequences on the character of the slave-holding class, as well as on society in general. Concurrently with the affirmation that slavery is not against the natural law, the moralists specify what are the natural inviolable rights of the slave, and the corresponding duties of the owner. The gist of this teaching is summarized by Cardinal Gerdil (1718-1802):

Slavery is not to be understood as conferring on one man the same power over another that men have over cattle. Wherefore they erred who in former times refused to include slaves among persons; and believed that however barbarously the master treated his slave he did not violate any right of the slave. For slavery does not abolish the natural equality of men: hence by slavery one man is understood to become subject to the dominion of another to the extent that the master has a perpetual right to all those services which one man may justly perform for another; and subject to the condition that the master shall take due care of his slave and treat him humanely (Comp. Instit. Civil., L, vii).

The master was judged to sin against justice if he treated his slave cruelly, if he overloaded him with labour, deprived him of adequate food and clothing, or if he separated husband from wife, or the mother from her young children. It may be said that the approved ethical view of slavery was that while, religiously speaking, it could not be condemned as against the natural law, and had on its side the jus gentium, it was looked upon with disfavour as at best merely tolerable, and when judged by its consequences, a positive evil.

The later moralists, that is to say, broadly speaking, those who have written since the end of the eighteenth century, though in fundamental agreement with their predecessors, have somewhat shifted the perspective. In possession of the bad historical record of slavery and familiar with a Christian structure of society from which slavery had been eliminated, these later moralists emphasize more than did the older ones the reasons for condemning slavery; and they lay less stress on those in its favour. While they admit that it is not, theoretically speaking at least, contrary to the natural law, they hold that it is hardly compatible with the dignity of personality, and is to be condemned as immoral on account of the evil consequences it almost inevitably leads to. It is but little in keeping with human dignity that one man should so far be deprived of his liberty as to be perpetually subject to the will of a master in everything that concerns his external life; that he should be compelled to spend his entire labour for the benefit of another and receive in return only a bare subsistence. This condition of degradation is aggravated by the fact that the slave is, generally, deprived of all means of intellectual development for himself or for his children. This life almost inevitably leads to the destruction of a proper sense of self-respect, blunts the intellectual faculties, weakens the sense of responsibility, and results in a degraded moral standard. On the other hand, the exercise of the slave-master's power, too seldom sufficiently restrained by a sense of justice or Christian feeling, tends to develop arrogance, pride, and a tyrannical disposition, which in the long run comes to treat the slave as a being with no rights at all. Besides, as history amply proves, the presence of a slave population breeds a vast amount of sexual immorality among the slave-owning class, and, to borrow a phrase of Lecky, tends to cast a stigma on all labour and to degrade and impoverish the free poor.

Even granting that slavery, when attended with a due regard for the rights of the slave, is not in itself intrinsically wrong, there still remains the important question of the titles by which a master can justly own a slave. The least debatable one, voluntary acceptance of slavery, we have already noticed. Another one that was looked upon as legitimate was purchase. Although it is against natural justice to treat a person as a mere commodity or thing of commerce, nevertheless the labour of a man for his whole lifetime is something that may be lawfully bought and sold. Owing to the exalted notion that prevailed in earlier times about the patria potestas, a father was granted the right to sell his son into slavery, if he could not otherwise relieve his own dire distress. But the theologians held that if he should afterwards be able to do so, the father was bound to redeem the slave, and the master the was bound to set him free if anybody offered to repay him the price he had paid. To sell old or worn-out slaves to anybody who was likely to prove a cruel master, to separate by sale husband and wife, or a mother and her little children, was looked upon as wrong and forbidden. Another title was war. If a man forfeited his life so that he could be justly put to death, this punishment might be committed into the mitigated penalty of slavery, or penal servitude for life. On the same principle that slavery is a lesser evil than death, captives taken in war, who, according to the ethical ideas of the jus gentium, might lawfully be put to death by the victors, were instead reduced to slavery. Whatever justification this practice may have had in the jus gentium of former ages, none could be found for it now.

When slavery prevailed as part of the social organization and the slaves were ranked as property, it seemed not unreasonable that the old juridical maxim, Partus sequitur ventrem, should be accepted as peremptorily settling the status of children born in slavery. But it would be difficult to find any justification for this title in the natural law, except on the theory that the institution of slavery was, in certain conditions, necessary to the permanence of the social organization. An insufficient reason frequently offered in defence of it was that the master acquired a right to the children as compensation for the expense he incurred in their support, which could not be provided by the mother who possessed nothing of her own. Nor is there much cogency in the other plea, i.e. that a person born in slavery was presumed to consent tacitly to remaining in that condition, as there was no way open to him to enter any other. It is unnecessary to observe that the practice of capturing savages or barbarians for the purpose of making slaves of them has always been condemned as a heinous offence against justice, and no just title could be created by this procedure. Was it lawful for owners to retain in slavery the descendants of those who had been made slaves in this unjust way? The last conspicuous Catholic moralist who posed this question when it was not merely a theoretical one, Kenrick, resolves it in the affirmative on the ground that lapse of time remedies the original defect in titles when the stability of society and the avoidance of grave disturbances demand it.


See ST. THOMAS, Summa Theologica I-II:94:3, ad 2um; II-II:57:3, ad 2um; II-II:57:4, ad 2um.

About this page

APA citation. Fox, J. (1912). Ethical Aspect of Slavery. In The Catholic Encyclopedia. New York: Robert Appleton Company.

MLA citation. Fox, James. "Ethical Aspect of Slavery." The Catholic Encyclopedia. Vol. 14. New York: Robert Appleton Company, 1912. <>.

Transcription. This article was transcribed for New Advent by Michael Tinkler.

Ecclesiastical approbation. Nihil Obstat. July 1, 1912. Remy Lafort, S.T.D., Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York.

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