 Others might query this second step, and, in particular, the claim that a “preference” to benefit others can ground an (enforceable) duty to do so. In general, whether people have a duty to others cannot be vindicated on the basis of a preference that some have to benefit others. This notwithstanding, some might still argue that where current generations can leave future generations better off than themselves at no cost, or at reasonable cost, then there is a duty to do so.