Function as Design versus Function as Usefulness

This paper argues for a radically different approach to normative function than the dominant etiological account, an approach with a broader explanatory agenda. Concepts of biological function address two related but distinct issues: understanding biological organisms as complex organized systems, and understanding the way in which parts have come to be present in organisms because of their adaptive value. The etiological account focuses primarily on the latter, treating the complex organization of organisms as a derivative issue solved in passing, as it were, by explanations for the presence of parts within organisms. This way of treating the issues is unsatisfactory, however, since the etiological model of normative function fails to provide the conceptual resources required for understanding the complex process interrelationships characteristic of organisms as organizationally integrated systems. Among other deficiencies, it makes normative functions epiphenomenal, it provides a limited account of dysfunction, and it is unable to adequately characterize multifunctional parts or the organization of densely connected functional complexes. In other words, although explanations for the presence of traits and explanations for the way organisms function as complex integrated systems certainly overlap, they are not conceptually or causally identical issues, nor can one issue be treated purely as derivative upon the other. Our approach recognizes this and develops an account of normative function that directly focuses on whole-system organization and process interdependence.