side by side with him does not? The explanation, in
simplest terms, is that the soldiers’respective levels
of vulnerability to post-traumatic stress disorder
differed.
The Value of Classification
Classification systems are necessary; otherwise, our
experience and our consciousness become a chaotic
array of events. By abstracting the similarities and
the differences among the events of our experience,
we can establish categories of varying width and
purpose that allow us to generalize and predict.
Clinical psychology is very much concerned
with the diagnosis, classification, and treatment of
mental illness. TheDSM-IV-TRsystem, although
clearly not perfect, will continue to be used by
contemporary clinical psychologists in their
research, consultation, and practice. All of us have,
and will continue to have, some disagreement with
theDSM-IV-TRor any other diagnostic system.
Diagnostic systems have their advantages and disad-
vantages, and the criteria for individual mental dis-
orders are fallible (Widiger & Trull, 1991). The
DSM-IV-TR, like its predecessors, has been accused
of being more useful for clinical research than for
clinical practice. This is probably why clinicians
often fail to use the diagnostic manual. However,
we hope that you are convinced that diagnostic
formulations are important because these formula-
tions have communication value, have potential
treatment implications, and facilitate psychopathol-
ogy research.CHAPTER SUMMARY
Clinical psychologists engage in the diagnosis and
classification of psychological problems. A single, all-
encompassing definition of what constitutes
“abnormality”is difficult to come by. In this chapter,
we have reviewed the pros and cons of three fre-
quently cited criteria for abnormal behavior:Stress absent Stress low Stress Medium Stress High
Diathesis absent Diathesis Low Diathesis Medium Diathesis High0246810
12
F I G U R E 5-4 Continuum of Vulnerability (Diathesis) and Stress
DIAGNOSIS AND CLASSIFICATION OF PSYCHOLOGICAL PROBLEMS 155