Limits to Aggregation and Uncertain Rescues

Abstract Limited aggregation holds that we are only sometimes, not always, permitted to aggregate. Aggregation is permissible only when the harms and benefits are relevant to one another. But how should limited aggregation be extended to cases in which we are uncertain about what will happen? In this article, I provide a challenge to ex post limited aggregation. I reconstruct a precise version of ex post limited aggregation that relies on the notion of ex post claims. However, building a theory of limited aggregation based on ex post claims leads to a dilemma. This shows that ex post limited aggregation is currently far away from being a well-defined alternative, strengthening the case for ex ante limited aggregation.