Standard impossibility theorems on judgment aggregation over logically connected propositions either use a controversial systematicity condition or apply only to agendas of propositions with rich logical connections. Are there any serious impossibilities without these restrictions? We prove an...

How can the propositional attitudes of several individuals be aggregated into overall collective propositional attitudes? Although there are large bodies of work on the aggregation of various special kinds of propositional attitudes, such as preferences, judgments, probabilities and utilities,...

We consider the classical problem of opinion pooling: the probability assignments of different individuals are to be merged into collective probability assignments. While opinion pooling has been explored in some depth in the literature (by statisticians, economists, and philosophers), all...

All existing impossibility theorems on judgment aggregation require individual and collective judgment sets to be consistent and complete (in some recent results with completeness relaxed to deductive closure), arguably a demanding rationality requirement. They do not carry over to aggregation...

We show that, when a group takes independent majority votes on interconnected propositions, the outcome is consistent once the profile of individual judgment sets respects appropriate structural conditions. We introduce several such conditions on profiles, based on ordering the propositions or...

In solving judgment aggregation problems, groups often face constraints. Many decision problems can be modelled in terms the acceptance or rejection of certain propositions in a language, and constraints as propositions that the decisions should be consistent with. For example, court judgments...

Several recent results on the aggregation of judgments over logically connected propositions show that, under certain conditions, dictatorships are the only independent (i.e., propositionwise) aggregation rules generating fully rational (i.e., complete and consistent) collective judgments. A...

We investigate judgment aggregation by assuming that some formulas of the agenda are singled out as premises, and the Independence condition (formula-wise aggregation) holds for them, though perhaps not for others. Whether premise-based aggregation thus defined is non-degenerate depends on how...

If a group is modelled as a single Bayesian agent, what should its beliefs be? I propose an axiomatic model that connects group beliefs to beliefs of group members, who are themselves modelled as Bayesian agents, possibly with different priors and different information. Group beliefs are proven...

A population''s level of terrorism depends on two factors: people''s preferences (would they like creating damage?) and the constraints under which people act (what damage could they create, and at what punishment?). Cause-related policies, e.g. improving social stability or education, aim at...