Interpreting the conjunction fallacy

Salvador Mascarenhas, NYU


In a seminal paper in 1983, Tversky and Kahneman showed that, with certain choices of content, human reasoners will consider a statement of the shape 'A and B' to be more probable than 'A'. According to probability theory, this is a fallacy, for the probability of a conjunction of independent propositions has to be less than or equal to the individual probabilities of its conjuncts. In this talk I present work in progress arguing that the conjunction fallacy is no fallacy at all, and can in fact be derived under reasonable assumptions about the interpretive processes involved.