The moral necessity of prohibiting polygamy is sometimes put forward as an immediate inference from the equality of the numbers of the two sexes. This argument, however, seems to require the assumption that all men and women ought to marry: but this scarcely any one will expressly affirm: and actually considerable numbers remain unmarried, and there is no reason to believe that in countries where polygamy is allowed, paucity of supply has ever made it practically difficult for any man to find a mate.