Mechanism and purpose: A case for natural teleology

This paper develops a naturalised account of teleological explanation. Any such account must be consistent with the completeness of mechanism. The account I offer of teleological explanation is adapted from a prominent approach to the understanding of causal-mechanistic explanations. In order to give a scientific explanation-whether it be mechanistic or teleological--one must provide two things: (i) an invariance relation and (ii) and an elucidating description. In a causal-mechanistic explanation there is an invariance relation between the mechanism and the effect. The elucidating description illustrates how the mechanism produces the effect. In a teleological explanation the invariance holds between the goal (effect) and the means (cause). The elucidating description illustrates the way the means conduces to the goal. Mechanistic and teleological explanations are both complete in their own right, and they are mutually autonomous. One cannot replace the other without explanatory loss. It follows, then, that some natural phenomena-those that contribute to goals-are susceptible of more than one complete, autonomous explanation. Teleology thus demonstrates the falsity of Jaegwon Kim's Explanatory Exclusion Principle.