The functions of delusional beliefs

Peter Kinderman and Richard P. Bentall

in Reconceiving Schizophrenia

Published on behalf of Oxford University Press

Published in print November 2006 | ISBN: 9780198526131
Published online February 2013 | e-ISBN: 9780191754340 | DOI:

Series: International Perspectives in Philosophy & Psychiatry

The functions of delusional beliefs

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To briefly conclude this chapter, it will be useful to consider the evidence we have just outlined in the context of our earlier examination of attempts to define delusional beliefs. It will be recalled that we argued that no satisfactory distinction could be drawn between delusions and other kinds of strongly held beliefs and attitudes. We also suggested that the strong emotional investment that people have in delusions and other strongly held beliefs might reflect, in some way, the role that these beliefs play in their evaluation of themselves. This certainly seems to be true of political and religious beliefs, which are often incorporated into individuals’ definitions of themselves (as in, ‘I am a Marxist’ or ‘I am a Christian’). It also seems to be true of paranoid beliefs. Although other common kinds of delusional systems have not been thoroughly investigated we suspect that this principle will extend to them also. This is perhaps obvious in the case of grandiose beliefs, in which the individual claims impossible identity (‘I am the son of God’), talents or riches. However, it may be equally true of less common delusions, for example the erotomanic patient's conviction that he or she is loved by someone important and famous (we may judge ourselves partly according to the mate we believe we are able to attract).

Of course, self-definition, although an important function of belief systems, is not the only function. Presumably, the human capacity for generating prepositional descriptions of the world evolved because it allows us to predict events in our environment, make preparations accordingly, and regulate our response to them. This is why human beings have developed efficient but non-logical strategies for inferring what is going on around them (the ‘heuristics’) and build their theories of the world on the basis of experience. Again, the paranoid patient does not appear to be noticeably different from anyone else in any of these respects. Whether this is so in the case of other delusional systems is less obvious. It is difficult to think of circumstances that would feed grandiose patients’ beliefs about themselves, for example. Perhaps in these cases, the quest for an emotionally acceptable self-definition outweighs the other functions that belief systems are ordinarily required to perform.

Even if this last speculation turns out to be true, the overall impression that emerges from psychological research into psychosis is that deluded patients belong to the same species as everyone else. They are more like the rest of us than different and belong to the same social world. By denying that delusions are beliefs, the conventional psychiatric approach treats patients with disrespect, and often denies them a voice in determining their own treatment (Bentall 2003). The clinical implications of the account we have offered of delusions are beyond the scope is this chapter; suffice it to say that we believe it is possibly to work with patients in a way that respects their theories and treats these theories as perhaps unlikely but just possibly true. By working with patients in this way, it is possible to engage them in a quest to discover the advantages and disadvantages of their way of thinking, and to encourage them to consider alternative beliefs systems. This approach lies at the core of the new cognitive behavioural treatments of psychosis (Morrison et al. 2003).

Chapter.  8664 words. 

Subjects: Psychiatry

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