Harry Potter and the sorcerer's scope: latent scope biases in explanatory reasoning

What makes a good explanation? We examine the function of latent scope , i.e., the number of unobserved phenomena that an explanation can account for. We show that individuals prefer narrow latent scope explanations—those that account for fewer unobserved effects—to broader explanations. In Experiments 1a–d , participants found narrow latent scope explanations to be both more satisfying and more likely. In Experiment 2 we directly manipulated base rate information and again found a preference for narrow latent scope explanations. Participants in Experiment 3 evaluated more natural explanations of unexpected observations, and again displayed a bias for narrow latent scope explanations. We conclude by considering what this novel bias tells us about how humans evaluate explanations and engage in causal reasoning.