[Abstractions and models: on the use of concepts in science]

Because of its reducing nature an abstract concept moves us away from the object under consideration. On the contrary, considering a formal pattern records and covers the known aspects of a configuration, the former brings us nearer to the latter. If we apply the notion of pattern to a depression it is of consequence to make a distinction between the pattern which describes the meaning of that depression and the one which states its justification. A sound epistemology prevents us from mistaking a meaning for a cause and a cause for a meaning. But is also places us before the fundamental and collective obligation of a double research: on the one hand, one which deciphers the psychodynamic mechanisms; on the other, one which detects the causal correlations of biological or social nature. Between these two orientations practice requires to make choices and compromises.