Does Incommensurability Matter? Incommensurability and Public Policy

Reasons are incommensurable when, and only when, they cannot be compared as better, worse, or equally good.' Incommensurability so conceived is relevant to choosing public policy because it is a barrier to realizing the following ideal: In forming public policy, we should select the policy supported by the best reasons. As an ideal, this surely seems uncontroversial. Time constraints, lack of information, and the vagaries of group political processes are, of course, barriers to realizing this ideal, as is incommensurability. The latter, however, is a significantly different barrier. When we encounter incommensurable reasons in crucial areas of public policy, we cannot do what we should do: Choose the option supported by the best reasons. This problem is significantly different from the problems posed by lack of time, lack of information, and the caprices of politics. The latter problems prevent us from realizing the ideal in practice; incommensurability prevents us from realizing the ideal in practice or in principle because it is impossible in principle to compare the relevant reasons. Does this mean that it is not generally true that we should select the policy supported by the best reasons? Must we, in cases of incommensurability, decide in some other way? Or,