 Collective decision-making can be subdivided into a deliberation phase, in which the individuals form or revise their judgments, and an aggregation phase, in which the post-deliberation judgments are fed into a voting rule which returns the decision (Dryzek &amp; List 2003). Diversity affects not only the judgment profile in the group at any given moment, and hence the aggregation process, but also the deliberation process. Deliberation owes its richness and fruitfulness largely to diversity. Non-diverse bodies gain little from deliberating: their members already reason similarly, take similar perspectives, know similar things, etc. In diverse bodies, deliberation can broaden the informational, perspectival, and methodological horizon. The more diversity, the more potential for judgment revision through deliberation.