Deliberating Collective Decisions

We present a dynamic model of sequential information acquisition by a heterogeneous committee. At each date agents decide whether to vote to adopt one of two alternatives or continue to collect more information. The process stops when a qualified majority vote for an alternative. Three main insights emerge from our analysis and match an array of stylized facts on committee decision making. First, majority rule is more fragile than super-majority rules to impatient committee members. Second, more diverse preferences, more consensual deliberation rules, or more unanimous de- cision voting rules lead to lengthier deliberation and more accurate decisions. Last, balanced committees unanimously prefer to delegate deliberation power to a moderate chairman rather than be governed by a deliberation rule such as unanimity.