The Problem of Purpose

Living organisms act purposefully, and their individual parts — organs, cells, organelles, molecules — fulfil purposes for the whole. Those purposes ‘come from within’; animals, for example, seek food and mates for themselves. In contrast, the purposes of technological products such as drawing pins, hat-stands and washing machines ‘come from outside’; they are defined by their makers and users. A washing machine does not wash clothes for itself.

Ever since the Scientific Revolution it has been agreed that the inanimate world of rocks, rivers, stars, clouds etc. does not act purposefully. It is to be understood in mechanistic not teleological terms. An inanimate object is not for anything or anyone; whatever it does is a consequence of antecedent causes. That implies a basic difference between biology on the one hand and physics and chemistry on the other. If biology is to be wholly compatible with physics, that difference needs to be resolved. We must be able to make complete mechanistic sense of purpose in biology.