 As yet there has been little reaction to these attempts to create hybrids and to draw on multiple principles in the attempt to provide a satisfactory theory of political obligation (but see Edmundson 2004, pp. 250–52). Those who doubt that such a theory can be constructed, however, are likely to say that combining principles, whether in hybrid or pluralist fashion, will not help, for combining a set of principles that are unsatisfactory individually will hardly produce a strong and satisfying theory (Simmons 2007, n. 17). Whether a plurality of principles is necessary or even desirable, in sum, remains one of many open questions with regard to the vexing problem of political obligation.