Fourth Problem: How to Honour Unanimous Preferences

Abstract

Monotonicity thus requires that it should never be harmful for an alternative if its support increases. Now if the support increases so as to reach unanimity, it would seem reasonable that the group should have its way precisely as it wishes. But what does unanimity mean in group decision making? Of course, if the group consists of n persons with exactly identical preference orders, then unanimity would be a straight-forward notion. But supposing that the group is not entirely homogeneous, but there are some alternatives with respect to which unanimity prevails, how could such an agreement of opinions be taken into account in social choices in a plausible way?