529. In 1459 there died at Arras a canon, eighty years old, who had committed incest with his daughters and with a granddaughter whom he had had by one of them.[1717]
530. Where the line is drawn, and why. The instances show that the notion of incest is by no means universal or uniform, or attended by the same intensity of repugnance. It is not by any means traceable to a constant cause. Plutarch[1718] discussed the question why marriages between relatives were forbidden by the traditional mores of his time. He conjectured various explanations. Fear of physical degeneration is not one of them. We must infer that such consequences had not then been noticed or affirmed. We have found cases in which no taboo existed and cases in which close intermarriages are especially approved. An operation of syncretism, when different usages and ideas have been brought together by conquest and state combinations, must be allowed for. In some cases a great interest was thought to be at stake; in other cases no importance was attached to the matter. The mores developed under the notions which got control by accident or superstition. There was no rational ground for the taboo, and none even blindly connected with truth of fact, until the opinion gained a footing that close intermarriage was unfavorable to the number or vigor of the offspring. Unless that opinion is accepted as correct there is no reason for the taboo now.[1719] Incest is, for us, a thing so repugnant that we consider the feeling "natural." We may test the feeling by our feeling as to the marriage of first cousins. First cousins are very commonly married in England. Such marriages are under no civil or ecclesiastical prohibition, and although many persons disapprove of them on grounds of expediency, and parents might refuse to consent to them, they do not come under the abomination of incest. In many states of the United States marriages of first cousins are illegal. In Kansas they are put under heavy penalties. We hear no preaching against close in-marriage. The matter is not discussed. The limitations are set in the current mores and are accepted without dispute. Evidently the only question is where the line should be drawn. If it was proposed to forbid the marriage of first cousins some discussion might be aroused. If it was decided wise to forbid such marriages, it would take long for such a sentiment of repugnance to be developed in regard to them as we now feel in regard to the marriage of sisters, or even of aunts and nieces. In history the movement must have been in the other direction. The repugnance arose first and then became a ground for the rules.
531. Human self-selection by taboo and other-worldliness. Laws against incest and all caste rules which arbitrarily limit the number of persons whom a given individual may marry may be regarded as blind attempts of mankind to practice some kind of self-selection. Sex selection inside the human race is the highest requirement which life now addresses to man as an intelligent being, and the very highest result which our sciences could produce would be to give us trustworthy guidance in a policy of sex selection. It is not possible for some persons to dispose of the life determination of others, as breeders control the union of beasts. What is needed is that individuals, in making their own decisions for their own self-realization, shall understand the whole range of interests which are involved, and shall do what it is expedient or necessary to do to satisfy them all. In times past men and women have thus limited themselves by rules about incest, group and class marriage, rank or caste, religion, wealth, and other considerations. In every society there are traits which are approved and others which are disapproved in each sex. In marrying, people are influenced by these appreciations and they select for or against them. Thus marriage is controlled by a complicated selection according to a number of standards which prevail at the time and place. At present the popular view seems to be that all standards are false, and that the limitations ought to be trampled on as representing abandoned ideals. It is thought that the whole matter ought to be left to the control of an unintelligent impulse, which is capable of any caprice, but whose authority is imperative. Perverse as the old restrictions often were, they had in them a notion of self-selection such as is needed now, if only the criteria and standards which are correct can be ascertained. The old restrictions contained a notion of breeding up, a notion which is by no means false, if we can get a rational idea of what is "up." No marriage ought now to be contracted without full application of all we know about heredity and selection. If, in any society, marriages were thus contracted, the effect would be most favorable on posterity, and on the power in action and the perpetuity of the group, for the net result would be that those who are least fit to propagate the race would be the ones who would be left unmarried or would marry each other. In the latter case their posterity would soon disappear, and the evil factors would be eliminated. A father now refuses his daughter to a drunkard, a criminal, a pauper, a bankrupt, an inefficient man, one who has no income, etc. Some men refuse their daughters to irreligious men, or to men who are not of their own sect or subsect. Some allow inherited wealth, or talent, or high character, etc., to outweigh disadvantages. In short, we already have selection. It always has existed. The law of incest was an instinctive effort in the same direction. The problem is the same now as it always has been,—to refine and correct the standards and to determine their relative importance.
532. Restrictions by biological facts as yet too uncertain. As yet, undoubtedly, the great reason why people are reluctant to construct a policy of marriage and population on biological doctrines is that those doctrines are too uncertain. The reluctance is well justified. Hasty action, based on shifting views of fact and law, would simply add new confusion and trouble to that produced by the customs and legislative enactments which we have inherited from the past and which were based on transcendental doctrines. So long as we do not know whether acquired modifications are inheritable or not, we are not prepared to elaborate a policy of marriage which can be dogmatically taught or civilly enforced. This much, however, is certain,—the interests of society are more at stake in these things than in anything else. All other projects of reform and amelioration are trivial compared with the interests which lie in the propagation of the species, if those can be so treated as to breed out predispositions to evils of body and mind, and to breed in vigor of mind and body. It even seems sometimes as if the primitive people were working along better lines of effort in this matter than we are, when we allow marriage to be controlled by "love" or property; when our organs of public instruction taboo all which pertains to reproduction as improper; and when public authority, ready enough to interfere with personal liberty everywhere else, feels bound to act as if there was no societal interest at stake in the begetting of the next generation.
533. It is self-evident that there ought to be no restriction on marriage except such as is necessary to protect some interest of the parties, their children, or the society. The necessity must also be real and not traditional or superstitious. The evils of inbreeding are so probable as to justify strong prejudice against consanguine marriages. If primitive men set up the taboo on incest without knowing this, they acted more wisely than they knew. We who have inherited the taboo now have knowledge which gives a rational and expedient reason for it. The mores, therefore, still have a field of useful action to strengthen and reaffirm the taboo. There is also a practical question still unsettled,—whether the marriage of first cousins should be included in the taboo.
[1658] Parkinson, Ethnog. d. Nordwestl. Salomo Ins., 6.
[1659] Snyder, Geog. of Marriage.
[1660] Anc. Soc., 424.
[1661] Marriage, 317.
[1662] Ibid., 319, 334, 352.