 A key  assumption in the proof May’s theorem and  subsequent  results is the  restriction to voting on  two  alternatives.  When there are only two  alternatives, the definition of a ballot can be simplified since a  ranking of two alternatives boils down to selecting the alternative  that is ranked first.  The  above characterizations of Majority  Rule work in a more general setting since they  also allow   voters to abstain  (which is ambiguous between not voting  and being indifferent between the alternatives).  So, if the alternatives  are  \(\{A,B\}\), then there are three possible ballots: selecting \(A\),  selecting \(B\), or abstaining (which is treated as selecting both \(A\) and \(B\)).   A natural question is whether there are May-style  characterization theorems  for more than two alternatives.    A crucial issue is  that  rankings of more than  two alternatives are much more informative than selecting an alternative or abstaining.  By  restricting the information required  from a  voter to selecting one of the alternatives or abstaining,  Goodin and List 2006 prove that the  axioms used in May’s Theorem characterize  Plurality  Rule when there are more than two alternatives.  They also show that a  minor  modification of the axioms characterize Approval Voting when voters are allowed to   select more than one alternative.  