Ludger Jansen

This chapter summarizes Aristotle's teaching about human nature. It reviews passages about human beings from his treatises on logic, psychology, ethics, politics, and biology, and discusses his famous characterizations of man as a rational and political animal (zoon logon echon; zoon politikon). It is argued that while Aristotle insists on the distinctive methods and varying reliability of different disciplines, his teachings about human nature can integrate into a unified picture. The notorious disputes among his interpreters about his stand on the immortality of the soul (or of one of its parts, the 'nous poietikos'), however, find their roots in the fact that Aristotle is vague and tentative in these more speculative bits of his anthropological thoughts.

In order to develop the ontology of tendencies for use in the representation of medical knowledge, tendencies are compared with other kinds of entities possessing the realizable-realization-structure, specifically: dispositions, propensities, abilities and virtues. The peculiarities of tendencies are discussed and a standard schema of tendency ascription is developed in order to represent the relations between the ascriptions of tendency tokens to particulars and the ascriptions of tendency types to universals. Two non-standard cases and their epistemic variants are discussed.

The concept of a function is central both to biology and to technology. But there is an intricate debate how functions as well as related entities like dispositions and roles are to be represented in top level ontologies and how they are to be related. We review important philosophical accounts and ontological models for functions and roles and discuss three models for the relation of functions and dispositions. We conclude that mainly because of the need to account for malfunctioning, functions should not be treated as a subtype of dispositions, but as their sibling category.