How should we define the feasible set? Even when individuals agree on facts and values, as traditionally construed, different views on feasibility may suffice to produce very different policy conclusions. Focusing on the difficulties in the feasibility concept may help us resolve some policy disagreements, or at least identify the sources of those disagreements. Feasibility is most plausibly a matter of degree rather than of kind. Normative economic reasoning therefore faces a fuzzy social budget constraint. Iterative reasoning about feasibility and (...) desirability may help us overcome these problems. (shrink)