The problems of defining his data and concepts and of communicating them have long bedeviled the student of psychopathology. Do the words with which he identifies any symptom or mental disease refer to events and explanatory ideas that other observers understand in the same way? And are these words always used with the same meanings?
In the present book, Mandler and Kessen undertake to provide some necessary guide lines toward developing a common, scientifically viable language in the field of psychology. Their explicit goal is toward “reducing vagueness” (p. 19) through a language which is to be characterized by precision. It is to refer to objects and events that are public. The terms are to be invariant, and so communicable that they consistently refer to the same events reported by any one observer at different times and among several observers at any