Richard Holton has drawn attention to a new semantic universal, according to which(almost) no natural language has contrafactive attitude verbs. This semantic universal ispart of an asymmetry between factive and contrafactive attitude verbs. Whilst factivesare abundant, contrafactives are scarce. We propose that this asymmetry is partly due toa difference in learnability. The meaning of contrafactives is significantly harder to learnthan that of factives. We tested our hypothesis by conducting a computational experimentusing an artificial neural network. The results of this experiment support our hypothesis
