An Interpretive Account of Logical Aggregation Theory

Judgment aggregation theory, or rather, as we conceive of it here, logical aggregation theory generalizes social choice theory by having the aggregation rule bear on judgments of all kinds instead of merely preference judgments. It derives from Kornhauser and Sager's doctrinal paradox and Pettit's discursive dilemma, two problems that we distinguish emphatically here. The current theory has developed from the discursive dilemma, rather than the doctrinal paradox, and the final aim of the paper is to give the latter its own theoretical development, along the lines of Dietrich and Mongin's recent technical work. However, the paper also aims at reviewing the main existing results, starting from the first impossibility theorem proved by List and Pettit. It provides a uniform logical framework in which the whole of theory can be stated and its theorems can be compared with each other. The account goes through three historical steps: the scattered early results on the independence axiom, the collective achievement of the canonical theorem which provided the theory with its specific method of analysis; and finally the recent extension mentioned above to the doctrinal paradox.