On the conjunction fallacy and the meaning of and, yet again: A reply to Hertwig, Benz, and Krauss (2008)

In this paper we question the theoretical tenability of Hertwig, Benz, and Krauss’s (2008) (HBK) argument that responses commonly taken as manifestations of the conjunction fallacy should be instead considered as reflecting “reasonable pragmatic and semantic inferences” because the meaning of and   does not always coincide with that of the logical operator ∧∧. We also question the relevance of the experimental evidence that HBK provide in support of their argument as well as their account of the pertinent literature. Finally, we report two novel experiments in which we employed HBK’s procedure to control for the interpretation of and. The results obtained overtly contradict HBK’s data and claims. We conclude with a discussion on the alleged feebleness of the conjunction fallacy, and suggest directions that future research on this topic might pursue.