Commentary on "Insight, Delusion and Belief"

If the psychiatric use of the concept of insight, as recently expounded by David (1990), Amador et al. (1991), Marková and Berrios (1992), Fulford (1993) and Amador and David (n.d.) is flawed—which it surely is—it is in the inadequate account of the intersubjectivity that allows shared informal norms to be set. Grant Gillett's thesis redresses this imbalance, and does so while avoiding the twin pitfalls of extreme intersubjective relativism and biological determinism. In the first case, critics such as R. D. Laing have caricatured the entire practice of psychiatry by describing psychosis as the disagreement between two persons where one is sane by common consent, yet held that what we label "psychosis" (delusions, thought interference and hallucinations), far from being, in Jaspers terms psychologically irreducible or ununderstandable, may be "socially intelligible" in the context of family relationships (see David 1986). In the second, prevalent assumptions such as "delusions are the result of excess dopamine in the neo-cortex" fail altogether to explain exactly what delusions are. Any fully satisfactory view on insight must allow room for the causal connections of neuroscience and self-reflexivity (as described by Gillett), that is, the ability to comment upon, judge, and evaluate one's own mental contents, which becomes attuned through the reciprocity of self and other.

This reappraisal has much to commend it. It is humane without being sentimental; complex without being fussy. Above all, it provides a stimulating synthesis of philosophy and clinical observation. General philosophical studies of insight and belief demand explanations of consciousness, morality, and the sense of self which seem to me, at least, to be overwhelming. Gillett's paper shows that just as, in the biological sciences, pathology has illuminated physiology, the study of psychopathology may, ultimately, illuminate both philosophy and normal psychology. Extreme pathology of insight is found in the psychoses, by definition, and in schizophrenia in particular. It is the contradictions inherent in the speech and behavior of patients with psychosis which, in my view, could provide some of the most important clues to the "big questions" in the philosophy of mind.

Consider then "normal insight" or self-reflexivity. This is rightly viewed as a highly developed, difficult-to-master, quintessentially human "skill" or "microcognitive function" that, while "moderately robust" (see below), is vulnerable to biological disruption. The words and phrases I have picked out in quotation marks imply that an information-processing account of insight must be discernable and also that the disruption of insight should reveal something of the underlying component processes in the same way as the aphasias tell us a great deal about how language is subsumed in the brain. This neuropsychological metaphor is particularly apt given the wide range of disorders of insight into disability that have been noted in neurology clinics for around a century (David, Owen, and Förstl 1993). Neuropsychologists such as Dan Schacter and associates (McGlynn and Schacter 1989) have proposed that each aspect of mental life (memory, language, etc.) has its own awareness subsystem, a microcognitive function that may be put out of action by damage or disease. In other words, insight(s) into cognitive function(s) is(are) modular (Fodor 1983).

Modularity has other defining properties that are of special relevance to the understanding of insight into psychosis, especially, informational encapsulation. This provides a good illustration of the way in which intuitive arguments of traditional philosophy may come unstuck. Take impossible delusions and other-directed insight in the psychotic individual, which Gillett discusses. It is not just that the deluded patient understands and accepts certain laws of physics and commonsense when applied to other people or neutral situations yet fails to apply the same rules to his or her own beliefs, it is that the person knows that the belief is impossible, even in his or her own case, yet somehow still believes it. It is this paradox, an extreme cases of highly informationally-encapsulated microcognitive dysfunction, that makes the study of the poor insight of the psychotic so perplexing and that the lay person recognizes as fundamentally mad. Another unavoidable and paradoxical fact from psychopathology is that even...