0. 0 Psychology versus Complex Systems Science Over the last century, psychology has become much less of an art and much more of a science. Philosophical speculation is out; data collection is in. In many ways this has been a very positive trend. Cognitive science (Mandler, 1985) has given us scientific analyses of a variety of intelligent behaviors: short-term memory, language processing, vision processing, etc. And thanks to molecular psychology (Franklin, 1985), we now have a rudimentary understanding of the chemical processes underlying personality and mental illness. However, there is a growing feeling-particularly among non-psychologists (see e. g. Sommerhoff, 1990) - that, with the new emphasis on data collection, something important has been lost. Very little attention is paid to the question of how it all fits together. The early psychologists, and the classical philosophers of mind, were concerned with the general nature of mentality as much as with the mechanisms underlying specific phenomena. But the new, scientific psychology has made disappointingly little progress toward the resolution of these more general questions. One way to deal with this complaint is to dismiss the questions themselves. After all, one might argue, a scientific psychology cannot be expected to deal with fuzzy philosophical questions that probably have little empirical signifi cance. It is interesting that behaviorists and cognitive scientists tend to be in agreement regarding the question of the overall structure of the mind."

1. GENERAL The term "diagnostics" refers to the general theory of diagnosis, not to the study of specific diagnoses but to their general framework. It borrows from different sciences and from different philosophies. Traditionally, the general framework of diagnostics was not distinguished from the framework of medicine. It was not taught in special courses in any systematic way; it was not accorded special attention: students absorbed it intuitively. There is almost no comprehensive study of diagnostics. The instruction in diagnosis provided in medical schools is exclusively specific. Clinical instruction includes (in addition to vital background information, such as anatomy and physiology) specific instruction in nosology, the theory and classification of diseases, and this includes information on diagnoses and prognoses of diverse diseases. What is the cause of the neglect of diagnostics, and of its integrated teaching? The main cause may be the prevalence of the view of diagnostics as part-and parcel of nosology. In this book nosology is taken as a given, autonomous field of study, which invites almost no comments; we shall freely borrow from it a few important general theses and a few examples. We attempt to integrate here three studies: ll of the way nosology is used in the diagnostic process; of the diagnostic process as a branch of applied ethics; ~ of the diagnostic process as a branch of social science and social technology.