One approach to the understanding of the function of a system is through its malfunction. That is, you can discover how it should work by observing how it sometimes does not work. This approach may initially appear to be ridiculous. Why observe a malfunctioning system when you might as well observe a functioning system? The logical answer is that a complete description of function should include possible sources of malfunction. But the best answer is probably more psychological than logical. We tend to take functioning systems for granted; it is only when they go wrong that we are motivated to understand them in order to repair them. The little I know about the internal combustion engine I owe to the fact that the ones I have owned tend to break down. The mechanic, in explaining what went wrong and what expensive things he must do to right that wrong, invariably informs me of how the system should work. Malfunction can be explained only in terms of function.

A similar motivation has provided us with considerable information about how the nervous system should function. Psychotherapists, confronted daily with patients whose nervous systems have "broken down", are strongly motivated to discover how the nervous system ought to work. The therapist-patient confrontation provides more motivation toward understanding than does the experimenter-subject confrontation, out of which has emerged most of the information presented so far in this book.

Disorders of the nervous system may be either functional or structural. In structural disorders the malfunction can be attributed to organic damage to the nervous system, whereas in functional disorders no such physical damage can be observed. Since this distinction is never applied to any other subsystem of the organism, a further consideration of it may cast additional light on the special status of the nervous system. This distinction applies only to your nervous system because, as argued in Section 2.2 it is the only system which "knows" the environment. A functional disorder can thus be considered as a structural disorder of the person-environment system.

If there is a structure corresponding to every function, then it would seem that there would be a malstructure corresponding to every malfunction. Thus functional disorders would appear to be simply those for which the organic damage has not yet been determined and the term functional merely a confession of ignorance. All that need be decided is which, in a particular disorder, is the precipitating cause. Structuralists point to the many mental aberrations precipitated by syphilis, and functionalists counter with the psychosomatic disorders caused by anxiety. Such effects are not surprising in the light of the intimate structure-function interaction. Indeed, it is surprising that anyone is surprised. Although, in particular cases, malstructure or malfunction may be the precipitating cause, most disorders involve a complex interaction between them. The malstructure-malfunction relationship, like the structure-function relationship, is a chicken-egg problem.

An extension of the analogy with the internal-combustion engine may clarify this distinction. If a car skids on an icy road, it would be futile to look for damage within the engine to explain this malfunction. It is a functional disorder. Unless the car skids into a tree, which damages the engine, this malfunction will not result in malstructure and thus further malfunction. However, since the driver has a memory, the event may persist in his nervous system and cause further malfunction. He may become excessively careful or nervous on icy roads and thus increase the chances of further accidents, or he may irrationally refuse to drive again under any circumstances. Since memory must have some structural basis, it could still be argued that a functional disorder is simply a structural disorder for which the physical damage has not yet been found. However, it is useful to distinguish between a system that is malfunctioning because it has been damaged and a system that is functioning as it should but with inappropriate content.

Consider the strange Case of the Locomotive God [LEONARD]. A university professor never left his small midwestern town throughout his lifetime, To do so, he would have had to cross railway tracks, which terrified him. His problem was traced back to an experience as a child in which he had almost got run over by a train. If the train had struck him and damaged his nervous system, then his aberration could be attributed to this structural damage. However, it didnÕt strike him, it simply scared him. His brain was working perfectly well but with inappropriate content. He had a functional disorder.

Some people tend to think that a functional disorder is less "real" or disturbing than a structural disorder. However, a hysteric who cannot use his hand, even though there is no organic damage, is just as incapacitated as a paralytic whose hand is indeed paralyzed. Indeed, a functional disorder may be even more disturbing. A doctor can tell a patient with tuberculosis precisely what is wrong, point out a dark patch on an X-ray picture, and explain exactly what he must do in order to be cured. A therapist cannot give the same reassurance to a client with neurosis.

The client does not have neurosis in the same sense as the patient has tuberculosis. Just as he does not have experiences but is his experiences, he does not have neurosis but is a neurotic. Since the nervous system is the basis of his personality, a disorder of his nervous system changes his personality. Joe with tuberculosis is still Joe, but Joe with neurosis is someone else. Furthermore, his symptoms interfere with his cure, since they disturb his relationship with his therapist. However, if the therapist can explain (or, rather, if the client can understand) the cause of the neurosis, he need not continue to explain the cure. In neurosis, unlike tuberculosis, understanding is the cure, or, at least, it is the first step towards a cure. Neuroses cannot be explained away, but they can be understood away.