One common criticism in the optimal taxation literature is the specification of the social welfare function. The optimal taxation literature (I have the Mirrlees framework in mind) relies on first specifying a social welfare function. However, because we never observe the social welfare function (SWF) and because we're not even sure if a reasonable specification of social welfare can be represented by a utilitarian-like SWF, what kind of policy prescriptions can we get out of these types of models? How much of a problem is this? Are there potential ways in which this problem can be made less offensive?