Here is my first stab, though likely to change.
The Myth of Mental Illness fifty years after publication: What does it mean today?
In the Myth of Mental Illness, Thomas Szasz offered, or at least appeared to offer, a number of arguments against the reality of mental illness. The most important is expressed in this passage:
The concept of illness, whether bodily or mental, implies deviation from some clearly defined norm. In the case of physical illness, the norm is the structural and functional integrity of the human body. Thus, although the desirability of physical health, as such, is an ethical value, what health is can be stated in anatomical and physiological terms. What is the norm, deviation from which is regarded as mental illness? This question cannot be easily answered. But whatever this norm may be, we can be certain of only one thing: namely, that it must be stated in terms of psychological, ethical, and legal concepts… [W]hen one speaks of mental illness, the norm from which deviation is measured is a psychosocial and ethical standard. Yet the remedy is sought in terms of medical measures that – it is hoped and assumed – are free from wide differences of ethical value. The definition of the disorder and the terms in which its remedy are sought are therefore at serious odds with one another.[Szasz 1972: 15]
The argument here starts from the assumption that mental illness and physical illness involve deviation from different norms. Medical intervention, however, is capable of addressing only one sort of deviation – that of physical illness – and thus it cannot address the kind of deviation from a norm implicit in mental illness. Since the conception of mental illness involves the idea that it can be so treated, there is something incoherent about the very idea.
Since medical interventions are designed to remedy only medical problems, it is logically absurd to expect that they will help solve problems whose very existence have been defined and established on non-medical grounds. [ibid: 17]
Szasz also develops a shorter version of this argument. If mental illness is a deviation from a psychosocial norm then this leads by itself to an objection from circularity:
Clearly, this is faulty reasoning, for it makes the abstraction ‘mental illness’ into a cause of, even though this abstraction was originally created to serve only as a shorthand expression for, certain types of human behaviour. [ibid: 15]
Whilst neither of these arguments is compelling, they do suggest an important result that has shaped the philosophy of psychiatry since. They are not compelling because, even if mental illness is defined by, or identified through, psycho-social norms, this need not imply that it is identical to or constituted by such deviation. It may be that the illness is the cause of the deviation such that, even though it is picked out by its characteristic effects, it is not identical to them. (Firing the gun may be picked out as the cause of the death of the president; but it is not identical to the death: it slightly predates it.) If so, Szasz’ argument fails. To establish his conclusion he would need to establish the truth of a kind of mental illness behaviourism which goes beyond highlighting the role of societal norms in picking out illness.
Although the argument for the stronger conclusion fails, it is enough to block a common assumption that shapes biologically minded psychiatry. The assumption is that a successful biological account of a psychiatric syndrome places the condition on the same footing as a physical illness or disease. It would remove it from the debates around anti-psychiatry about deviation from societal norms. But that does not follow. If Szasz is right that conditions are only picked out as illnesses through deviations from societal norms, an aetiological account of the causes of such deviations does not remove the conceptual connection between mental illness and societal norms.
Thus what seems most important to the debate within philosophy of psychiatry about the nature of mental illness is Szasz’ premiss: that mental illness is picked out or identified in psychological, ethical, or legal terms. (In fact, Szasz himself recently suggested that the proposition that mental illness is a myth was not the conclusion of an argument he offered but something he accepted as a premise [Szasz 2004: 321]. This perhaps suggests that he did not aim to move much beyond the claim that mental illness is an essentially evaluative notion. That is why I said he may merely have appeared to offer an argument for the myth of mental illness.)
Szasz’ premiss also highlights a genuine complexity at the heart of current debate about psychiatric taxonomy. Assuming that deviation from a societal norm plays a key role in picking out mental illness, how is it to be specified? It might be specified either in terms which presuppose the concept of illness – hence a pathological deviation from a societal norm – or they might be specified in some other illness-independent terms. One, albeit implausible, example of the latter would be simply to say that any deviation from the – still to be defined – central norms is indicative of illness. Less implausibly, one might suggest mental illness is identified via specific politically defined deviations. This would be a Foucaultian reading of a broadly Szaszian approach to mental illness. It would also be a form of reductionism. The concept of illness would be reduced to other independent concepts. The alternative, by contrast, has to take illness or pathology to be a primitive, that is irreducible, term.
Take the case of those people who claim that the inner voices that they hear are indicative not of a pathology but of their membership of a different community. Their experiences are a deviation from a societal norm but does the deviation also amount to a pathology? The underlying problem now takes the form of a dilemma. If one can specify in illness-independent terms the kind of deviation that amounts to a pathology, then one has a neutral ground to assess the status of hearing voices. But, given the general failure of reductionist programmes within philosophy, that seems a difficult task. On the other hand, if the deviation in question has always to be understood in illness-involving terms, that will provide no help where the pathological status of an experience is precisely what is in question.
(PS: An update and Szasz’ reply is here.)
Szasz, T. (1972) The Myth of Mental Illness, London: Paladin
Szasz, T. (2004) ‘Reply to Bentall’ in Schaler, J.A. (ed) Szasz Under Fire, Chicago: Open Court: 321-6