If this conclusion be accepted, it will follow that the more widely distributed varieties of the classificatory system of relationship are associated with a social structure which has the exogamous social group as its essential unit. This position has only to be stated for it to become apparent how all the main features of the classificatory system are such as would follow directly from such a social structure. Wherever the classificatory system is found in association with a system of exogamous social groups, the terms of relationship do not apply merely to relatives with whom it is possible to trace genealogical relationship, but to all the members of a clan of a given generation, even if no such relationship with them can be traced. Thus, a man will not only apply the term “father” to all the brothers of his father, to all the sons’ sons of his father’s father, and to all the sons’ sons’ sons of his father’s father’s father, to all the husbands of his mother’s sisters and of his mother’s mother’s granddaughters, etc., but he will also apply the term to all the members of his father’s clan of the same generation as his father and to all the husbands of the women of the mother’s clan of the same generation as the mother, even when it is quite impossible to show any genealogical relationship with them. All these and the other main features of the classificatory system become at once natural and intelligible if this system had its origin in a social structure in which exogamous social groups, such as the clan or moiety, were even more completely and essentially the social units than we know them to be to-day among the peoples whose social systems have been carefully studied. If you are dissatisfied with the word “classificatory” as a term for the system of relationship which is found in America, Africa, India, Australia and Oceania, you would be perfectly safe in calling it the “clan” system, and in inferring the ancient presence of a social structure based on the exogamous clan even if this structure were no longer present.

Not only is the general character of the classificatory system exactly such as would be the consequence of its origin in a social structure founded on the exogamous social group, but many details of these systems point in the same direction. Thus, the rigorous distinctions between father’s brother and mother’s brother, and between father’s sister and mother’s sister, which are characteristic of the usual forms of the classificatory system, are the obvious consequence of the principle of exogamy. If this principle be in action, these relatives must always belong to different social groups, so that it would be natural to distinguish them in nomenclature.

Further, there are certain features of the classificatory system which suggest its origin in a special form of exogamous social grouping, viz., that usually known as the dual system in which there are only two social groups or moieties. It is an almost universal feature of the classificatory system that the children of brothers are classed with the children of sisters. A man applies the same term to his mother’s sister’s children which he uses for his father’s brother’s children, and the use of this term, being the same as that used for a brother or sister, carries with it the most rigorous prohibition of marriage. Such a condition would not follow necessarily from a social state in which there were more than two social groups. If the society were patrilineal, the children of two brothers would necessarily belong to the same social group, so that the principle of exogamy would prevent marriage between them, but if the women of the group had married into different clans, there is no reason arising out of the principle of exogamy which should prevent marriage between their children or lead to the use of a term common to them and the children of brothers. Similarly, if the society were matrilineal, the children of two sisters would necessarily belong to the same social group, but this would not be the case with the children of brothers who might marry into different social groups.

If, however, there be only two social groups, the case is very different. It would make no difference whether descent were patrilineal or matrilineal. In each case the children of two brothers or of two sisters must belong to the same moiety, while the children of brother and sister must belong to different moieties. The children of two brothers would be just as ineligible as consorts as the children of two sisters. Similarly, it would be a natural consequence of the dual organisation that the mother’s brother’s children should be classed with the father’s sister’s children, but this would not be necessary if there were more than two social groups.

I should have liked, if there were time, to deal with other features of the classificatory system, but must be content with these examples. I hope to have succeeded in showing that the social causation of the terminology of relationship goes far beyond the mere dependence of features of the system on special forms of marriage, and that the character of the classificatory system as a whole has been determined by its origin in a specific form of social organisation. I propose now to leave the classificatory system for a moment and inquire whether another system of denoting and classifying relationships may not similarly be shown to be determined by social conditions. The system I shall consider is our own. Let us examine this system in its relation to the form of social organisation prevalent among ourselves.

Just as among most peoples of rude culture the clan or other exogamous group is the essential unit of social organisation, so among ourselves this social unit is the family, using this term for the group consisting of a man, his wife, and their children. If we examine our terms of relationship, we find that those applied to individual persons and those used in a narrow and well-defined sense are just those in which the family is intimately concerned. The terms father, mother, husband and wife, brother and sister, are limited to members of the family of the speaker, and the terms father-, mother-, brother-, and sister-in-law to the members of the family of the wife or husband in the same narrowly restricted sense. Similarly, the terms grandfather and grandmother are limited to the parents of the father and mother, while the terms grandson and granddaughter are only used of the families of the children in the narrow sense. The terms uncle and aunt, nephew and niece, are used in a less restricted sense, but even these terms are only used of persons who stand in a close relation to the family of the speaker. We have only one term used with anything approaching the wide connotation of classificatory terms of relationship, and this term is used for a group of relatives who have as their chief feature in common that they are altogether outside the proper circle of the family and have no social obligations or privileges. They are as eligible for marriage as any other members of the community, and only in the very special cases I considered in the first lecture are they brought into any kind of legal relation. The dependence of our own use of terms of relationship on the social institution of the family seems to me so obvious that I find it difficult to understand how anyone who has considered these terms can put forward the view that the terminology of relationship is not socially conditioned. It seems to me that we have only to have the proposition stated that the classificatory system and our own are the outcome of the social institutions of the clan and family respectively for the social causation of such terminology to become conspicuous. I find it difficult to understand why it has not long before this been universally recognised. I do not think we can have a better example of the confusion and prejudice which have been allowed to envelop the subject through the unfortunate introduction of the problem of the primitive promiscuity or monogamy of mankind. It is not necessary to have an expert knowledge of the classificatory system. It is only necessary to consider the terms we have used almost from our cradles in relation to their social setting to see how the terminology of relationship has been determined by that setting.

This brief study of our own terms of relationship leads me to speak about the name by which our system is generally known. Morgan called it the “descriptive system,” and this term has been generally adopted. I believe, however, that it is wholly inappropriate. Those terms which apply to one person and to one person only may be called descriptive if you please, though even here the use does not seem very happy. When we pass beyond these, however, our terms are no whit more descriptive than those of the classificatory system. We speak of a grandfather, not of a father’s father or a mother’s father, only distinguishing grandfathers in this manner when it is necessary to supplement our customary terminology by more exact description. Similarly, we speak of a brother-in-law, and only in exceptional circumstances do we use forms of language which indicate whether reference is being made to the brother of the husband or wife or to the husband of a sister. Such occasional usages do not make our system descriptive, and if they be held to do so, the classificatory system is just as descriptive as our own. All those peoples who use the classificatory system are capable of such exact description of relationship as I have mentioned. Indeed, classificatory systems are often more descriptive than our own. In some forms of this system true descriptive terms are found in habitual use. Thus, in the coastal systems of Fiji the mother’s brother is often called ngandina (ngane, sister of a man, and tina, mother), this term being used in place of the vungo already mentioned. Similar uses of descriptive terms occur in other parts of Melanesia. Thus, in Santa Cruz the father’s sister is called inwerderde (inwe, sister, and derde, father). This relative is one for whom Melanesian systems of relationship not infrequently possess no special designation, and the use of a descriptive term suggests a recent process which has come into action in order to denote a relative who had previously lacked any special designation.

If “descriptive” is thus an inappropriate name for our own system, it will be necessary to find another, and I should like boldly to recognise the direct dependence of its characters on the institution of the family and to speak of it as the “family system.”

While I thus reject the term “descriptive” as a proper name for the terminology of relationship with which we are especially familiar, it does not follow that there may not be systems of denoting relationship which properly deserve this title. In Samoa a mode of denoting relatives is often used in which the great majority of the terms are descriptive. Thus, the only term which I could obtain for the father’s brother’s son was atalii o le uso o le tama, which is literally “son of the brother of the father,” and there is some reason to suppose that this descriptive usage has come into vogue owing to the total inadequacy of the ancient Samoan system to express relationships in which the peoples are now interested.

The wide use of such descriptive terms is also found in many systems of Europe, as in the Celtic languages, in those of Scandinavia, in Lithuanian and Esthonian.[32] A similar mode of denoting relationships is found in Semitic languages and among the Shilluks and Dinkas of the Anglo-Egyptian Sudan, and since it is from these peoples that I have gained my own experience of descriptive terminology, I propose to take them as my examples.