By Lisa Bortolotti
Madness and irrationality may seem inextricably related. “You are crazy!” we say, when someone tells us about their risk-taking behaviour or their self-defeating actions. The International Classification of Diseases (ICD-10) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) describe people with depression, autism, schizophrenia, dementia, and personality disorders as people who infringe norms of rationality. But not all people diagnosed with a mental disorder behave irrationally, and not all people who behave irrationally are diagnosed with a mental disorder.
There is evidence that people with a diagnosis of schizophrenia, depression, or autism are, in some contexts, more epistemically rational, that is, more responsive to evidence and more likely to form true beliefs, than people without any psychiatric diagnosis. People make more accurate predictions when they are depressed, because the statistically normal way to make predictions is characterized by excessive optimism. People with autism score higher in social interaction games (such as Prisoner’s Dilemma) and are more logically consistent than control participants when making decisions involving possible financial gain, by not responding to emotional contextual cues in the same way as controls (see Tateno 2013 and De Martino et al. 2008). People with schizophrenia are also less vulnerable to a statistically normal but irrational tendency to gamble when faced with a certain loss (Brown et al. 2013).
It is interesting to consider the possibility that even delusions, a paradigmatic example of irrational beliefs, and a symptom of mental disorders such as schizophrenia and dementia, serve to restore epistemic functionality that was previously compromised. That is, they may temporarily allow an agent to acquire, retain and use appropriately true beliefs of importance to her.
First consider a young man who finds himself in hospital with both his legs paralysed as a result of an accident. He is in a state of despair; his negative emotions are overwhelming (McKay and Dennett 2009) and compromise his capacity to relate to his physical and social environment. Coming to believe that his legs cannot move due to arthritis, as opposed to a permanent paralysis, may help him overcome that moment of despair.
Now consider a woman who is subject to a distressing anomalous experience. Almost everything seems to have a special meaning, the doorbell ringing at 12 o’clock, the radio playing that Elton John song, her son’s teacher wearing a red blouse, but the special meaning of these facts remains mysterious. Mishara and Corlett suggest that the delusion puts an end to an often long period of great anxiety during which the agent is constantly expecting something important to happen. The doorbell ringing, the song, the red blouse are all messages by the secret services, communicating to the woman that her husband is having an affair. Now there is an explanation and the sense of unpredictability and expectation stops. Attention can be deviated from the stimuli previously experienced as salient and distressing. Due to the adoption of a delusional hypothesis, automated processes of learning can resume and the capacity to respond to cues in the environment is enhanced.
Obviously, delusions are not a good thing. The young man with anosognosia overcomes despair by adopting a very implausible belief that is not supported by the evidence available to him. The woman experiencing random events as salient is finding everywhere confirmation for a belief that is completely unjustified. Epistemic faults are so central to our understanding of delusions that they appear prominently in the definition of delusions: for instance, in the DSM-5, delusions are “fixed beliefs that are not amenable to change in the light of conflicting evidence”. Believing something false, often absurd, such as the content of a delusion (“I am dead”, “My wife has been replaced by an impostor”, “The queen wants me dead”, “President Obama is secretly in love with me”), can cause internal conflict and create a gap between the agent and the people around her. The agent may be challenged about her delusion at first, then viewed as unreliable and untrustworthy when she does not respond to evidence and argument, and finally laughed at or ignored. The ensuing social isolation then contributes to the rigidity of the delusion: the agent no longer feels like she can talk about her delusion, and receives no further challenges, and the delusion “sticks”.
It seems important to start thinking about the evaluation of “imperfect cognitions” in a way that reflects the standard limitations of human agents and the circumstances in which they find themselves due to anomalous experience, biased reasoning, impaired memory, dysregulated mood or emotions. When no useful interaction can be had with the social and physical environment, a false and irrational belief that helps overcome the crisis remains false and irrational, but I call it epistemically innocent.
Lisa Bortolotti is Professor of Philosophy at the University of Birmingham, International Perspectives in Philosophy and Psychiatry Series Editor. She is author of Delusions and Other Irrational Beliefs, has written for The Oxford Handbook of Philosophy and Psychiatry, Psychiatry as Cognitive Neuroscience, amongst others.