 The question judgment aggregation addresses is how we can define aggregation procedures that preserve individual rationality at the collective level. From a philosophical point of view, such question concerns the nature of group attitudes such as group beliefs (Roth 2011). When the city council decides to build the bridge, the decision is taken on the basis of individual beliefs that, for example, the bridge will have a positive impact on the development of the economic activities in the area and does not represent an environmental threat. Thus, the formal approach to judgment aggregation can serve to cast light on the dependence between individual and collective beliefs (if there are any). The questions tackled by judgment aggregation are also relevant for the testimony problem investigated in social epistemology (Goldman 1999, 2004, 2010). How shall the diverging opinions of experts in a panel be combined and how should a rational agent respond to such disagreement?