Non-disjunctivist conceptions of mind are presented blithely throughout the corpus of philosophical psychopathology, as if we could and should just take it for granted that they are the only show in town. I don't want to - don't know how to - don't really know what it would mean to - argue against them here, only to point out the different direction that a disjunctivist conception takes us. (I say 'don't really know what it would mean to...' because, to be honest, I don't really think that disjunctivism and non-disjunctivism are best understood as two opposing philosophical positions about the formal character of experience. Rather, I would posit disjunctivism as a non-position, a grammatical reminder which somewhat exceeds itself, still slightly under the sway of the (very idea of the meaningfulness of the) metaphysics that at best it aims to 'cancel' rather than oppose.)
Recall what the non-disjunctivist says about perceptual experience (I take (rather from memory), as my source, John McDowell's paper Criteria, Defeasibility, and Knowledge - although it should be noted that McDowell doesn't actually talk about 'disjunctivism' per se): that the possibility of my not being able to distinguish, on occasion, whether I am hallucinating from whether I am having a (so-called (by philosophers)) 'veridical perception' entails that the two cases have some 'highest common factor' (e.g. an inner experience, a sense datum, a mental image) in common. Against this the disjunctivist insists that in 'veridical perception' (let's just call it 'perception' shall we!) - in perception - the content of my experience is no inner proxy, no half-way-house-to-the-object, but rather: the object itself. When I see my cat, that is what I do - I do not need to be presented more 'proximally' with a visual image, a sense datum, an inner experience, of a cat. I've got the damn thing itself right in front of me, thank you very much. (So there is a 'disjunct' between the two cases - no common item of an inner cat image in cat hallucinations and cat perceptions.)
Now the kind of non-disjunctivism I have in mind in the philosophy of psychopathology is not simply that contained in the typical empiricist's (non-disjunctivist) conception of hallucination (although that is widespread enough). It is rather an analogue of this in a wider range of psychotic phenomena. What makes it analogous is the similar philosophical inventing of a whole class or form of (parts of) experiences, a class which is posited so that it can do apparent explanatory work (but which putative work will only itself seem to be required on the basis of some rather non-disjunctivist-like conceptions of experience itself...).
Take Zahavi- or Frith- or Graham-esque conceptions of self-consciousness. Here it is typically assumed that - from the fact that the patient experiencing passivity experiences has an experience as of, or just: of, someone else thinking my thoughts, putting thoughts in my mind that are not my own, extracting them, moving my body instead of me moving it - the non-patient must normally be having contrary (albeit subliminal) experiences of being the agent of their own thoughts/actions. Failures of this agency can then be appealed to in an alleged explanation of the psychopathological phenomena. But I can see no more evidence for this everyday tacit 'ipseity'-sense, for this automatic experience of myself as the agent of my own actions, than I can for the presence of sense data in the case of genuine perception.
I want to leave those examples for now, and turn instead to depersonalisation and derealisation - experiences of the self or the world as being unreal. From the presence of these we have the common inference that we must normally have some belief or experience or sense of the world or the self as real, genuine, objective, independent. It is then suggested that it is to some kind of failure in this mechanism of providing a sense of the real that we owe the psychopathological phenomena. (I seem to recall Matthew Ratcliffe arguing in a similar way - that we have some normal feeling of this or that facet of being-in-the-world which feelings of being (or 'senses of reality') can be disrupted in psychopathological self-disturbances.) But I see no reason why such putative normal senses of reality should be posited. Just because I may sometimes have a feeling of unreality does not entail that I normally have a feeling of reality that has been supplanted. (I may sometimes feel hungry. This does not mean that, when I don't, I always have a feeling of fullness, or just a feeling of satiation (although perhaps I might, after a nice meal). Rather I just don't feel hungry when, well, when I don't feel hungry.)
The extra explanatory potency of the 'non-disjunctivist's' conception should be clear: by positing a 'feeling of reality' I can 'explain' feelings of unreality as due to the breakdown of some normal part of our affective relating to the world. But, honestly, this seems just far too 'neat'. First, I'm not aware of any such feelings of 'reality' in the normal case (what would be the point of them anyway?). Secondly, it just won't do to invent explanantia for the job when confronted with puzzling explananda. Thirdly, just why is it that I take myself to be in need of some such explanation? Fourth, aren't we being misled by the psychopathology, asked to buy into the very conditions of (im)possibility of psychotic experience that it is precisely part of its pathologicality to tacitly posit?
Er, I think I ought to explain what I mean. So, compare the unreality experience to the sceptic's predicament. With everyday being-in-the-world, I need no 'feelings of being' to sustain my living conscious engagement with my surroundings and with others. I just, you know, get on with it. But in psychosis existential terror throws me out of this; and with scepticism, in an intellectual rather than lived register, I also stop viewing my understanding as, necessarily, always-already, embedded in a world. The mind now understands itself as a self-contained inner domain. It will now seem that there ought to be thoughts or feelings which bridge the gap between mind and world. A feeling of reality would do the trick nicely, where a feeling of unreality has come on the scene and threatens to unseat one's whole grasp of what is true, meaningful, real. But from within this 'sceptical' construction the fly cannot escape from the flybottle: once the seed of sceptical doubt has found fertile ground, there is nothing that can stop it growing and growing in the mind - not all the epistemology in the world can have the desired effect of intellectually sanctioning what is so valuable about Hume's walk to the billiards table from the study.
We might compare the predicament here with that of someone living under, or in the sway of, an unconscious phantasy. An existential-phenomenological recasting of such phantasy has it that something (some emotional understanding) which would ideally be revealed within 'the clearing' (in the 'intentional field') has now become part of its very structure. I inhabit an atmosphere which, in its all-pervasiveness, is peculiarly transparent to me (if not to the perceptive other). Attending from this phantasy, rather than to what would normally be its worldly contents, throws up a set of concerns for me, into consciousness, which concerns are actually irresolveable (and I am left simply with an unconscious 'compulsion to repeat' (actually, as Lear points out, it's not a compulsion to repeat - just a non-satiated compulsion to do that-which-is-repeated)) within this framework. Within the phantasy all the fly can do is bounce around the bottle; it takes a particularly skilled Wittgensteinian entomologist to show him out, not by solving the presenting puzzle but by untying the underlying phantasy.
Let me wrap up a little. What I have analogically been calling the 'non-disjunctivist' conception of psychotic experiences such as depersonalisation has it that these are on a par with putative normal experiences of 'personalisation' or 'realisation' (as it were) - that they represent a subjective registering of the breakdown of those faculties which allegedly normally give rise to the alleged sane varieties of affectively toned everyday encounters. What this theoretically presupposes is, I believe, an analogue of that conception of the mind presupposed by the non-disjunctivist about perceptual experience: some kind of 'inner world' or domain of 'sense data / phenomenological items' present in both hallucinatory and non-hallucinatory episodes as a common inner currency. The epistemological task now becomes that of finding one's way out of this inner landscape. The problem is that this is an impossible task. Rather than look for ways out (causal links of the 'right kind' etc.) of the inner world, we would do better to question its very premises. So, too, I have been suggesting, (semi-)psychotic experiences of derealisation might invite us to understand them as just further contents of consciousness, contents perhaps standing on a par with alleged other such contents (such as alleged feelings of 'reality'). But, I want to suggest, the decisive trick has taken place further back in the mind - not in what contents present themselves to consciousness, but rather - in the structuration of the field of experience which gives rise to the abnormal sensings. Because this field is something which can only be inhabited, not itself experienced, the fact of its distorted involution cannot be registered. Trying to 'think' one's way out of it - give oneself reasons for returning from the study to the billiards table - will inevitably be a doomed enterprise.
Those who move swiftly to explanatory theories of psychotic experience have, it seems to me, often failed to take in, in a first phenomenological sweep, just how very odd such experience is. 'Oh yes, depersonalisation, that happens in x % of people, is characterised by xyz, etc etc.' Hang on a minute, just listen to what you're saying! De-person-alisation! De-real-isation! A sense of the self or world as being unreal! What could that possibly be! I'm not trying to question the disturbing fact of the experience, only to invite us to linger a little longer over the idea that it is in any way obvious what its content is. Such a failure to linger and a flight to explanation sits well with that kind of (non-disjunctive) conception of the mind - as a domain that might quite naturally be populated by feelings of either reality or unreality - tacitly on offer. But wait! Are we really confident that we have either any clear sense of what it would be for an experience to be of something - or myself - as real or as unreal? Sitting with the bare thought of it, it can start to look like a strange philosophical joke. Deja vu is not dissimilar in this respect: the feeling presents itself as an uncanny feeling of having seen something or been somewhere before which we believe we haven't seen or been. But it isn't as if we have a quite general normal experience of having seen something before (is it?), or as if we don't in fact very often take ourselves to recognise people or places who or which, in fact, we had not previously encountered. Such formulations far-too-quickly invite us to reduce the uncanniness of the experience to the contradiction between 'I have' and 'I haven't' seen her or it before. Far from taking us nearer to the bizarreness of the experience, we are left - by the too-quick acceptance of how the psychotic experience articulates itself - further and further away from it.