Abstract

Mark Crooks effectively demolishes Dennett's theory by concentrating on its internal defects. In which case I would like to contribute to this discussion by examining some scientific evidence that may be relevant. Dennett claims that hallucinations do not involve any actual sensory element but only a change in our beliefs. A schizophrenic does not actually hear the voices he complains about--he develops the false belief that he is hearing something. This puts hallucinations on a par with the patient's delusions e.g. his false belief that other people are persecuting him. The majority view, in contrast, is that hallucinations represent defective function in the sensory system. In this impasse, evidence from functional magnetic resonance imaging studies should help. These allow us to identify those areas of the brain that are activated under the conditions we are interested in. If the majority are right, then a subject having hallucinations should show increased activity in some part of his sensory brain. On the other hand, if Dennett is right, the subject should show no such increased activity but, instead, possibly abnormal activity in the part of the brain related to the formation of delusions. To answer this question I performed a Medline search of the literature on imaging studies in hallucinations occurring under various circumstances. The results were interesting. 2012 APA, all rights reserved)