Coalitions under demand revealing
Notes
T. NICOLAUS TIDEMAN and GORDON TULLOCK* Riker's (1979) criticism of the demand revealing process 1 essentially involves pointing out a number of opportunities for coalitions that are raised by the process. He apparently uses the word coalition a little differently than we do, and the first two cases that he mentions, on pages 878-881, are not regarded as coalitions by Piker although we would have so regarded them. This is merely a matter of language and we see no point in debating language.
In a way Riker's comment is more properly considered as a comment on Tullock's (1977) article 'Demand revealing processes, coalitions, and public goods' rather than the article in the JPE (Tideman and TuUock, 1976). In our JPE article, 2nd paragraph, we said '... all existing social choice processes are subject to exploitation by suitable designed coalitions. This process is no exception.' Further, on pages 1157 and 1158 we discussed in some detail a general method of producing coalitions in a rather more complex setting than Piker has used.
Thus, in demonstrating that coalitions are possible, Piker is pushing on an open door. Coalitions are also possible in all other voting procedures and our claim for superiority of the demand revealing process did not involve alleging that coalitions were not possible. At the time we wrote that article, we thought that demand revealing shared with other voting methods the problem of coalitions and was superior on certain other dimensions.
It is true that since we wrote this article Tullock published in a special issue of Public Choice, edited by Tideman, an article in which it was argued that in the politically relevant cases, where there are many voters and many possible outcomes, public goods considerations would normally make coalitions impossible. Only one of Piker's examples, however, turns on the large number case and hence we could confine our attention to that one case and accept the rest of his article. We feel, however, that the general subject of coalitions under public choice deserves further airing and we have