Jaspers has appeared recently in the pages of the Journal both to support the impossibility of studying psychopathology scientifically (Reference TurnerTurner, 2003) and to defend the notion of a delusion arising as a consequence of the modularisation of a nonmodular belief system, linked to dopamine dysfunction (Jones, in Reference Jones, H./Delespaul and van OsJones et al, 2003), and thus of a scientific psychopathology. Jaspers has also been cited as an outmoded influence on psychopathological thinking, which should now be discarded (Delespaul & van Os, in Reference Jones, H./Delespaul and van OsJones et al, 2003). Such a disagreement may hinge upon Jaspers' conception of a primary delusion.

For Jaspers the primary delusion has two elements. First, there is a radical change in subjectivity: ‘We observe that a new world has come into being’ (Reference JaspersJaspers, 1963: p. 284). Such a new world is more than the presence of a false belief, it is a transformation of experience as a whole. Second, there is the element of meaning: ‘All primary experience of delusion is an experience of meaning’ (Reference JaspersJaspers, 1963: p. 103). ‘The experiences of primary delusion are analogous to this seeing of meaning, but the awareness of meaning undergoes a radical transformation’ (Reference JaspersJaspers, 1963: p. 99).

Jones, drawing on Campbell's work on delusions (Reference CampbellCampbell, 2002), wishes to recruit Jaspers as a rationalist. This is the concept that pathological top-down mechanisms can render delusions explicable. Portraying Jaspers thus misrepresents his position, as the conception he offers us of primary delusion is one of a new state of consciousness, and this may be as resistant to mechanistic explanation as is normal consciousness (the so-called ‘hard problem’; Reference ChalmersChalmers, 1996). In this respect, Jaspers may be better thought of as a ‘mysterian’ (Reference McGinnMcGinn, 1993). Mysterians hold that although consciousness is biologically mediated, it is inexplicable mechanistically. Nowhere in the General Psychopathology does Jaspers discuss the mechanism of primary delusion and he explicitly rejects a modular conception of psychopathology, as envisaged by his contemporary Wernicke: ‘As soon as this theory is transferred to everything psychic as if it were analogous it ceases to further our knowledge’ (Reference JaspersJaspers, 1963: p. 537). The existence of primary delusion is left as an ‘ununderstandable’ fact.

Delespaul & van Os want to discard the concept of primary delusion. In doing so they address only what Jaspers terms ‘delusion-like ideas’. Jaspers would have had no difficulty regarding these on a continuum with normal beliefs and it is by virtue of this that he regarded them as understandable. Primary delusions are left untouched on this account and yet they remain central to the clinical experience of major psychosis – the radical and sometimes rapid transformation from a given way of perceiving, thinking, affecting, acting to another, which colours all of subjective experience.

We agree that progress in psychopathology is dependent upon overcoming Jaspers' pessimism about understanding primary delusion. How this can be achieved remains an open question but progress may not come if we misrepresent Jaspers' great contribution.