1. Defining Marriage
‘Marriage’ can refer to a legal contract and civil status, a religious rite, and a social practice, all of which vary by legal jurisdiction, religious doctrine, and culture. History shows considerable variation in marital practices: polygyny has been widely practiced, some societies have approved of extra-marital sex and, arguably, recognized same-sex marriages, and religious or civil officiation has not always been the norm (Boswell 1994; Mohr 2005, 62; Coontz 2006). More fundamentally, while the contemporary Western ideal of marriage involves a relationship of love, friendship, or companionship, marriage historically functioned primarily as an economic and political unit used to create kinship bonds, control inheritance, and share resources and labor. Indeed, some ancients and medievals discouraged ‘excessive’ love in marriage. The ‘love revolution’ in marriage dates popularly to the 18th century (Coontz 2006, Part 3).
Ethical and political questions regarding marriage are sometimes answered by appeal to the definition of marriage. But the historical and cultural variation in marital practices has prompted some philosophers to argue that marriage is a ‘family resemblance’ concept, with no essential purpose or structure (Wasserstrom 1974). If marriage has no essential features, then one cannot appeal to definition to justify particular legal or moral obligations. For instance, if monogamy is not an essential feature of marriage, then one cannot appeal to the definition of marriage to justify moral or legal norms of monogamy. To a certain extent, the point that actual legal or social definitions cannot justify purportedly essential elements of marriage is just. First, past applications of a term need not yield necessary and sufficient criteria for applying it: ‘marriage’ (like ‘citizen’) may be extended to new cases without thereby changing its meaning (Mercier 2001). Second, appeal to definition may be uninformative: for example, legal definitions are sometimes circular, defining marriage in terms of spouses and spouses in terms of marriage (Mohr 2005, 57). Third, appeal to an existing definition in the context of debate over what the law of marriage, or its moral obligations, should be risks begging the question: in debate over same-sex marriage, for example, appeal to the current legal definition begs the normative question of what the law should be. However, this point also tells against the argument for the family resemblance view of marriage, as the variation of marital forms in practice does not preclude the existence of a normatively ideal form. Thus, philosophers who defend an essentialist definition of marriage offer normative definitions, which appeal to fundamental ethical or political principles. Defining marriage must depend on, rather than precede, ethical and political inquiry.