The moral grammar of marriage rules

According to theories of “moral grammar,” judgments of what is wrong or right – like judgments of what is ungrammatical or grammatical – are guided by implicit, often unconscious rules. An ideal test case for exploring the parallels between moral rules and language rules is the moral regulation of mating in relation to kinship. Here I argue that combinatorial variation in both kin terminologies and marriage rules results from the operation of a grammar faculty, which juggles tradeoffs between conflicting constraints according to the principles of “Optimality Theory.” This works to produce kinship grammars, input-output systems that map some kin types onto others via mergers and reductions. This in turn can yield marriage rules. If a kin type maps onto a close consanguine, this corresponds to a marriage proscription. If a kin type maps onto a close affine, this corresponds to a marriage prescription/preference. I analyze both elementary structures of kinship (where cross kin are prescribed spouses, and parallel kin are proscribed; e.g. Dravidian southern India) and complex structures (where kin are divided into an unmarriageable core and a marriageable periphery, and affines are sometimes tabooed because they are equated with close consanguines; e.g. Jane Austen’s England). Rather than treating social organization as the source of mental categories, this analysis starts with the machinery of categorization and shows how it spontaneously generates marriage rules. The result is an updating of structuralism in light of cognitive science: moral codes vary within limits set by fundamental structures of the human mind.