Thinking on delusional thinking is changing. The stock textbook image of a person invariantly and rigidly holding on to a certain belief has been challenged by Garety (1985). Similarly, the assumption that a deluded person can never be argued out of a held belief has been invalidated by Rudden et ale (1982). Early emphasis on the content and deviance of the belief (e.g. Jaspers 1962; Freedman et ale 1975) has been replaced by emphasis on the evidence for it, how it relates to the person's intelligence, education and background and on the manner in which the belief is held (Moor and Tucker 1979). The dichotomous view, i.e, that a person either has delusions and hallucinations or does not (rather as a woman is either pregnant or not), has been quashed by Strauss (1969), Chapman and Chapman (1980)and Chapman et ale (1982). Delusions, like hallucinations, exist on continua from arguably justifiable and mildlyparanoid or eccentric thoughts which could be entertained by anyone (and probably are) through to examples of fully blown bizarrity and impossibility based on little or no evidence. The traditional search for deficit and disadvantage in paranoid and deluded patients is now being counteracted by some research that shows them to have areas of superiority over normal non-psychiatric controls (e.g. La Russo 1978; Magaro 1981; Claridge 1988) and which argues that they possibly carry a survival advantage (Jarvik and Deckard 1977) - see also Heston and Denney (1968) and Karlsson (1972).