Group Deliberation and the Transformation of Judgments: An Impossibility Result
LSE PSPE Working Paper No. 4
37 Pages Posted: 24 Dec 2007
Date Written: 8 March 2007
While a large social-choice-theoretic literature discusses the aggregation of individual judgments into collective ones, there is relatively little formal work on the transformation of individual judgments in group deliberation. I develop a model of judgment transformation and prove a baseline impossibility result: Any judgment transformation function satisfying some initially plausible conditions is the identity function, under which no opinion change occurs. I identify escape routes from this impossibility result and argue that successful group deliberation must be 'holistic': individuals cannot generally revise their judgments on a proposition based on judgments on that proposition alone but must take other propositions into account too. I discuss the significance of these findings for democratic theory.
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