One of the more difficult issues that evolutionary theory has contended with over the years has centered around the role of the word “purpose.” Does life have a purpose or are we just random chemical processes that manage to copy themselves? I’m about to try and convince you that 1) The question as I just asked it is a set of false alternatives, 2) that people today pose the question in this manner because they have an inadequate understanding of causality, and 3) that the reasons for this difficulty are historical. So I’m going to have to start by telling you some stuff about the history of science and philosophy.
Most people seem to be willing to agree that other people are capable of acting with a purpose “in mind.” In fact, we often associate purposive or goal-oriented behavior with the property of “having a mind.” Well, a few centuries ago, “having a mind” was also connected to “having a soul.” And since everybody knew that only humans had souls, Descartes did not have to make much ado about pinning a dog to a board and having it vivisected alive for purposes of inquiry into the workings of the soulless machine. These days the concept of an eternal soul has drifted out of fashion, and this has contributed to the growing awareness that most vertebrates, at the very least, appear to have minds and are capable of suffering and vanity just like us. The trouble with life is that this purposiveness appears to extend all the way down to things which we agree clearly don’t have “minds,” such as bacteria. Also, despite the fact that we know that evolution is itself not being directed by any consciousness, it certainly appears to be in some way increasing in complexity as time has passed. What could it mean for nature to be acting with a purpose, but not with a purpose “in mind?” The scientific response to this question was delayed by, or perhaps took a necessary detour through, the deterministic interpretation of classical mechanics. What do I mean by this?