Function and Teleology

Abstract

Abstract Teleology is the study of purposes and goals. While humans and other intelligent creatures can act on purposes, are there purposes in nature, too? Biologists often explain the development of organisms, the behavior of plants and animals, and the working of body parts and processes, in terms of their ‘purposes’, ‘goals’, or ‘functions’. This gives rise to a philosophical problem: how can we make sense of teleological language in the life sciences? Important philosophical definitions of ‘biological function’ include the selected effects theory, the goal‐contribution theory, and the causal role theory, among others. A related problem is understanding the concept of ‘goal directedness’. Key Concepts Teleology is the study of goals and purposes. Teleological language such as ‘function,’ ‘goal’, and ‘purpose’ is prevalent in the life sciences. Philosophers and scientists disagree about whether teleological language is consistent with modern science and its avoidance of supernatural explanations. Philosophers debate the correct definition of ‘biological function.’ The ‘selected effects theory’ holds that the function of a trait depends on what it was selected for, by natural selection. The ‘goal‐contribution theory’ holds that a function of a trait depends on its contribution to survival or reproduction. The ‘causal role theory’ holds that a trait's function depends on its contribution to some interesting system capacity. It's possible that biologists use ‘function’ in multiple senses. There are philosophical problems surrounding the concept of goal directedness as well.