The problem of judgment aggregation poses a number of interesting questions.
One question is whether this problem raises a difficulty for the relationship between group rationality and group reason, in particular whether it raises a difficulty for one strategy for arguing that there are no requirements of group rationality as such. In 'Reasons and Rationality: The Case of Group Agents', Philip Pettit and I explore ways in which this difficulty might be resolved.
Another question is whether and to what extent this problem reappears in the case of credence (or degrees-of-belief) aggregation. In 'Groupthink', Jeffrey Sanford Russell, John Hawthorne, and I extend the established work on credence aggregation with two new results. We take conditionalization as a basic constraint, and explore two kinds of rules that allow credence aggregation: rules that use fixed prior credences and rules that use geometric averaging.