Modern atheist evolutionists tell us that nature is completely purposeless, yet works toward an end, namely survival. For the most part this end is assumed and never questioned. Few people seem to see a conflict in the idea that nature is mindless and random, yet driven toward an end. Thomas Aquinas thought of this position 750 years ago and called it absurd. In On Truth (De Veritate), Q5.A2, Thomas says:
Whatever does not have a determinate cause happens by accident. [If the contrary] were true, all the harmony and usefulness found in things would be the result of chance. . . . This explanation, of course, is absurd, for those things that happen by chance, happen only rarely; we know from experience, however, that harmony and usefulness are found in nature either at all times or at least for the most part. This cannot be the result of mere chance; it must be because an end is intended. What lacks intellect or knowledge, however, cannot tend directly toward an end. It can do this only if someone else’s knowledge has established an end for it, and directs it to that end. Consequently, since natural things have no knowledge, there must be some previously existing intelligence directing them to an end, like an archer who gives a definite motion to an arrow so that it will wing its way to a determined end.
If we assume that the basic natural phenomenon per se (such as gravity, friction, heat, momentum, etc.) are not directed toward an end, then we are reduced to this question: Can we explain movement and action in the universe through basic natural phenomenon, in which case nothing is ever truly directed toward an end, or is there causal agents that direct things toward and end?
Naturalists, at least the ones that have thought about the question, hold to the former, saying that the universe is “causally closed,” there are no active agents in the world creating any causes toward an end, no movement toward a goal. They say that everything we see is the result of complex series of pure, mindless, unguided forces. Theists, in our case Christians, would hold that there are causal agents, we can create action on our own, and that there is more in the world than natural forces.
It would seem an awfully big pill to swallow to hold that natrual forces explain all movement, there are no causal agents, and nothing we observe truly works toward an end. I maintain we do observe beings in the world working toward and end, therefore more exists than pure matter. We have always called this a soul.
I had an atheist once ask me “what sort of instrument can I use to measure the soul?” which is a logical question if you are a pure materialist. I did not ask him whether he thought his question was the result of pure natural forces, and whether he realized his desire for an answer really did not exist, for according to his worldview, nothing works toward an end. I also did not ask him how he held that natural selection could work when nothing works toward an end.
It would therefore be much more logical to hold to theism, which says things do indeed work toward an end, we have souls, and we are causal agents, which was the rest of Aquinas’ explanation.