The ultimate goal of public policy is to advance the substantive values that characterize a conception of the good society. Achieving political feasibility and operating within various resource constraints are important as instrumental values, things the reader desire not necessarily for their own sake but because they allow us to obtain policies that promote substantive values. The specification of a social welfare function, which converts the utilities of all individuals into an index of social utility, provides an alternative approach to defining economic efficiency and aggregate welfare. when analysts specify hypothetical social welfare functions to rank alternative policies, perhaps to make explicit the consideration of distributional issues, they tend to make the social welfare functions depend only on immediate consequences so as to keep the burden of prediction manageable. The distinction between valuing alternative distributions and valuing alternative institutions is relevant no matter what normative framework underlies the assessment of social welfare.