Shades of Determinism and Levels of Reality
Determinism refers to a particular feature of the world by which every event that occurs is the inevitable outcome of precisely operating physical laws on simple and complex systems. Many arguments and misunderstandings arise from not recognizing that there are different shades of determinism which are applicable to different levels of physical reality.
First there is the macroscopic level of reality which was investigated by classical physics with great success. Here, as far as we know, perfect determinism reigns. Let us imagine a marble sliding through a narrow winding tube which is held in a slanted position. We can expect the marble to land at a precise point at the opening of the tube. One may compare the winding tube to the laws of nature, and the rolling marble to every aspect of the physical world at the classical level. This is the world of billiard balls and planets, of spinning tops, running streams, swinging pendulums, and such. Perfect determinism reigns here. Tracking down the motions of such bodies with mathematical precision is among the great intellectual achievements of the first three centuries of modern science.
Next there is the classical statistical level of reality. This too belongs to the macrocosm, except that here we have systems consisting of stupendously large numbers of components. Gas in an enclosure would be a good example. It is made up of zillions of molecules which are moving within the confinement every which way. They collide with one another, not unlike billiard balls on a pool-table. They bounce back and move, and bump again. No one can keep track of the individual molecules. Their movements are all in strict accordance with the laws of motion and collision, they are all subject to the force of gravity and the principles of energy and momentum conservation. In principle, the motion of every single molecule can be quantitatively analyzed, as Laplace had stated. However, this is beyond even collective human capacity. But knowing the temperature of the gas one can compute how many of molecules will be moving within a given range of speeds. Such analyses are among concerns of what is known as statistical mechanics.
When we move into the realm of atoms, electrons and nuclei, we are entering an entirely new world: the microcosm. This level of reality is what physicists call the quantum level. Here things are quite different from the classical level. Here too there is some sort of determinism. This quantum physical determinism is an imperfect determinism. That is to say, there are calculable margins within which microcosmic entities evolve. It is somewhat like the zigzag motion of a marble on a fairly broad plane, like a child’s slide. We can know roughly where the marble will land, but the exact point of landing will not always be the same. (This is only an analogy. Of course, in the case of the marble, we can calculate precisely where it will land if we know certain parameters, such as the initial conditions of projection, the frictional coefficient of the slide, the air resistance, etc.) The principle of indeterminacy in the quantum world has given rise to countless philosophical and theological interpretations.
The next level of indeterminacy arises from the chaos principle. Chaos, in the technical sense, occurs when a dynamical system is far too complex to be analyzed even via the methods and mathematics of statistical analysis. Formations of clouds and changes in the stock market have their causes, no doubt, but it is impossible to track them down in the way classical or quantum physics explores phenomena, though linear differential equations. These and other occurrences in the physical world are instigated by non-linear processes where the result is not just the sum of the component parts. In those features of the world where chaos and complexity hold sway, old-time scientific prediction is simply impossible. It must be emphasized that chaos does not imply that there are supra-physical laws governing some situations, but that in enormously complex situations the resultant of the operation of the natural laws on its various parts becomes virtually intractable. As Steven Weinberg remind us, “It has been known for almost a century that the long-term behavior of such (non-linear) systems often exhibit chaos, an exquisite sensitivity to the initial conditions of the system.”
Nevertheless, some have tried to connect chaos theory with freewill. Doyne Farmer, for example, said: “On a philosophical level, it struck me as an operational way to define freewill, in a way that allowed you to reconcile freewill with determinism. The system is deterministic, but you can’t say what it’s going to do next…” Others have seen divine action in chaos phenomena. Thus, for example, one author has suggested that: “God, being omniscient, sees all the intricate workings of chaotic systems. He knows where tiny changes world have huge effects later on. This enables Him to act providentially in many situations to produce a desired result. Such speculations add little to our knowledge of the world, but they have endopotent value.