Nonmanipulable decision mechanisms for economic environments

In the social choice literature studying the problem of designing institutions for collective decision making, it is customary to (implicitly) assume that each dimension of the social outcome is of public interest (i.e., that each individual's welfare depends on every dimension of the outcome). Thus, the scope of the conclusions obtained is very limited. Here social decision problems with and without that public character are considered and it is shown that the same negative results arise in most cases; namely, that only dictatorial mechanisms are immune to the participants' manipulations. These results are obtained without requiring that the mechanisms produce Pareto optimal outcomes (they must simply be minimally responsive to the participants' preferences), which deepens their pessimistic character.I am deeply grateful to my advisor, Mark Walker, for his continuous guidance and encouragement. I wish also to thank Salvador Barberà, John Weymark, and two anonymous referees for helpful comments.