Natural kinds, normative kinds and human behavior

The main thesis of this paper is that a large part of human behavior cannot be understood in terms of natural kinds but by appealing to normative kinds. In the first section we explain the distinction between natural kinds and normative kinds. In the second section we focus on the notion of "human behavior", proposing a distinction between type A and type B behaviors and pointing out that psychology deals with type B behaviors, which are also included as diagnostic criteria for mental disorders. In the third section we analyze the strategies used in biomedical research to find specific etiologies ("essences") in order to explain such disorders. We argue that their results are inconsistent and that the lack of biomarkers that are clinically useful to refine the diagnoses is due to the fact that, unlike certain neuropathologies, there are no physiological essences behind such disorders. On the other hand, we argue that, as we are dealing with type B behaviors, we must interpret mental disorders as normative kinds.