Harsanyi invested his Aggregation Theorem and Impartial Observer Theorem with utilitarian sense, but Sen described them as "representation theorems" with little ethical import. This critical view has never been subjected to full analytical scrutinity. The formal argument we provide here supports...

Suppose that a group of individuals must classify objects into three or more categories, and does so by aggregating the individual classifications. We show that if the classifications, both individual and collective, are required to put at least one object in each category, then no aggregation...

We reexamine some of the classic problems connected with the use of cardinal utility functions in decision theory, and discuss Patrick Suppes's contributions to this field in light of a reinterpretation we propose for these problems. We analytically decompose the doctrine of ordinalism, which...

Judgment (or logical) aggregation theory is logically more powerful than social choice theory and has been put to use to recover some classic results of this field. Whether it could also enrich it with genuinely new results is still controversial. To support a positive answer, we prove a social...

Nudge is a semantically multifarious concept that originates in Thaler and Sunstein's (2008) popular eponymous book. In one of its senses, it is a policy for redirecting an agent's choices by only slightly altering his choice conditions, in another sense, it is concerned with bounded rationality...

This handbook chapter covers the existing theoretical literature on social preference and social welfare under risk (i.e., when probability values enter the data of the situation) and uncertainty (i.e., when this is not the case and only subjective probability assessments can be formed). Section...