A Computational Logic Approach to the Belief Bias in Human Syllogistic Reasoning

Psychological experiments on syllogistic reasoning have shown that participants did not always deduce the classical logically valid conclusions. In particular, the results show that they had difficulties to reason with syllogistic statements that contradicted their own beliefs. We consider a syllogistic reasoning task carried out by Evans, Barston and Pollard, who investigated the belief-bias effect with respect to syllogisms. We propose a formalization of the belief-bias effect for human syllogistic reasoning under the Weak Completion Semantics, a logic programming approach that aims at adequately modeling human reasoning.