The Genius of Kinship: The Phenomenon of Human Kinship and the G ...

of judgments to the study of reasoning, meaning the comparison of judgments (De Morgan, 1859b, p. 354).² De Morgan was looking for a logical basis for the classical shadow of judgment, namely invention. Traditional logic allows only two relations: identity (is) and non-identity (is-not). De Morgan argued that thought, in fact, is full of kin relations all of which equally well predicate identity or equality. He then identified the nature of kinship copulas: kin terms are convertible (if A is a brother of B, then B is a brother of A), transitive (if A is a descendant of B and B is a descendant of C, then A is a descendant of C), and capable of combining into relative products (if A is the father of B and a brother of C, then A is a nephew of C). While relative products can be constructed in discourse out of relational nouns (for example, a friend of a colleague of), they are lexicalized only as kin terms. In essence, De Morgan discovered that human thought generates not only syllogisms (from Greek syn ‘with’ and logos ‘word,’ ‘reason’), but also syngenisms (from Greek syn ‘with’ and genos ‘race, stock, kin’), although he stopped short of phrasing it this way.³ If rephrased, syngenism means “kin cognition,” namely the use of organic connections between humans as a model for the processing of inorganic information.

De Morgan's work prompted an early response by Canadian-born mathematician Alexander MacFarlane, who at first openly dismissed it (“As he [De Morgan] does not deal with exact ideas, he cannot give any exact results” [MacFarlane, 1879, p. 224]) and then disposed of a mere reference to it (MacFarlane, 1882).⁴ Instead, he chose to gear his work to L. H. Morgan as well as to Francis Galton, John F. McLennan, Henry Maine, and Edward Tylor. MacFarlane instantly realized that what L. H. Morgan described so pompously as “classificatory” kinship systems, is a typical logical class or “grade,” which he had drawn out “before hearing of L. H. Morgan's classificatory systems” (MacFarlane, 1882, p. 52). He anticipated the later critique of the Morganian dichotomy “classificatory-descriptive” (see, e.g., Kroeber, 1909) noting that the classificatory principle is present in every nomenclature, and hence does not constitute a singular property of kin terminologies in America, Australia, and Oceania.