It is easy to construct pairs of sentences X, Y that lead many people to ascribe higher probability to the conjunction X-and-Y than to the conjuncts X, Y. Whether an error is thereby committed depends on reasoners' interpretation of the expressions "probability" and "and." We report two experiments designed to clarify the normative status of typical responses to conjunction problems.
Katya Tentori, Nicolao Bonini, Daniel N. Osherson