Newtonian physics is also "mechanistic" in the sense of dispensing with "teleology," which played so important a role in Aristotelian science. That is, in Newtonian physics the behavior of a system can be predicted without invoking any "final cause" (any future "end" toward which it is tending, or "goal" toward which it is striving). Rather, it is enough to know the past state of the system and the laws of physics. This fact contributed to the idea that nature is "blind" and without "purpose." It should be noted, however, that a somewhat more teleological way of looking at Newtonian physics is possible. In the eighteenth and nineteenth centuries...powerful ways were developed to reformulate Newtonian mechanics in terms of the so-called "least action principle." A similar principal for optics, called the "least time principle," had been formulated a century earlier by Pierre Fermat (1601-65). The least time principle said that in traveling from some initial point to some final point a beam of light will follow the path which takes the least time. To solve for the light's path using this principle, one must therefore know in advance both where the light begins and where it is going to end up. The analogous principle in mechanics says that any system will evolve from its initial configuration to its final configuration by following the sequence of intermediate configurations (called the "trajectory," "path," or "history") that minimizes a quantity called the "action" (usually denoted S).

This passage comes from Professor Stephen M Barr's short and highly read-able A Student's Guide to Natural Science. Here is a comparison in brief between Aristotle's physics and the Newtonian physics which supplanted it. I have noted before, half tongue-in-cheek, that Aristotle's four causes can be applied to physics, provided that we are willing to look beyond physics for a "final cause."

To give some background explanation, Aristotle taught that there are four causes to a thing. That is to say, if I ask, "Why does a thing exist?" I am also asking "what causes the thing to exist?" and there are four answers to this question, all of which are necessary though not necessarily sufficient in order for the thing to exist. These causes are the material cause, the formal cause, the efficient cause, and the final cause.

To explain these four things as regards an object, let's look at a common example: a table. The material cause of a thing is the stuff out of which a thing is made--its material; for the table, this might be wood. The formal cause is the form (or shape) in which the matter is arranged; for a table, this is could be four legs and a level tabletop. The efficient cause is the "primary source of the change or rest," that is, the laws governing how the thing is made; for the table, this might be carpentry or woodworking. The final cause of a thing is the purpose or end (telos) for which the thing is made or for which it strives; the table is made as a work surface or a place to eat.

What of the sciences? Francis Bacon, one of the early scientific revolutionaries, argued that the only causes relevant to natural science--aside from the actual laws themselves--are the material and efficient causes (Advancement of Learning). According to this view, natural sciences study the material properties of a thing (the material cause) and the rules which govern that thing (efficient causes). I disagree with his analysis, though not only because of examples like the one cited by Professor Barr above. For one thing, it could be argued that all the laws of nature (or at least of physics) can be arranged as "formal causes."

There is, however, a different division which might be made. Consider a ball in motion. As a physicist, I can study the motion of the ball, but I begin by assuming that there is a ball and that it does move: that is, I assume both of the material causes. Now, so long as the ball is thrown somewhere near the earth's surface, it's trajectory should roughly describe a parabola; but this is the formal cause of the ball's motion, at least regarding its position as a function of time! So, kinematics describe not the efficient cause of an object's motion, but rather the formal cause. The efficient causes are then the other laws and theories which govern the ball's motion: Newton's Force Laws; Conservations of Energy, Momentum, and Angular Momentum; Newton's Theory of Gravitation, perhaps modified by Einstein's Relativity Theories. Moreover, Dr Barr argues that even the final cause may properly be studied by physics, in the form of the action (namely, the path that the ball takes will tend to minimize the action)--though I think it can be argued as to whether this is in fact an efficient cause or a final one.

Suppose I grant that this is a type of final cause or "teleological physics." The ball's end is therefore to follow the path which requires the lest amount of action, and it does so invariably unless some other outside entity prevent it from doing so. Could I not therefore also say that the ball's end is to conserve angular momentum, or energy? Teleology certainly makes its way into biology in this way, namely through evolutionary theories which require the end of a creature--or at least of a species--is to survive and to propagate the species. This should certainly cheer at least some of my fellow theists, who look back to Genesis and see the first commandment given to all creatures: "And he [God] blessed them, saying: Increase and multiply, and fill the waters of the sea: and let the birds be multiplied upon the earth" (Genesis 1:22).

Whether there is teleology or no in the natural sciences, there is certainly teleology outside of them. None of the causes so far listed--up to and including the teleological ones--are sufficient to explain the examples listed. This is true even when all of the causes so far listed are taken together. A table is not made merely because I have wood and a knowledge of how to put it together into the shape of a table. Neither are all of Newton's Laws, his theory of gravity, the Least Action Principle, or the differential equations underlying motion with acceleration sufficient to explain why a ball is thrown, even after we assume that there is a ball to be thrown.

An additional final cause is necessary, beyond the teleological "Least Action Principle" or "Survival and Propagation" desires of biology. I throw the ball because it is fun, or because I am playing a game. I build a table because I need a place to eat or to work. Science has little or anything to say about this particular version of the final cause--or perhaps I should more accurately call it the ultimate final cause. Science has little to say about, for the very simple reason that it is beyond the competence of science to speak of this kind of final cause, since this kind of final cause is in my volition or will.

Here science runs into its fundamental limit. The late Fr Stanley L Jaki explains:
"Science is competent wherever and whenever the object of investigation offers a quantitatively determinable aspect. The range of science is not limited either by the dimensions of quarks or by the distances of the farthest galaxies. Science touches on all matter—whether solid, liquid, gas, plasma, or a mere flow of energy waves—insofar as matter is extended and therefore measurable. Consequently, science is applicable wherever there is matter in any form whatsoever, because all matter has quantitative parameters. In that sense science is limitless and its statements are unlimitedly, that is, universally valid throughout the universe of matter….Science, insofar as it deals with quantities, is not limited by non-quantitative considerations. No non-quantitative set of considerations, be they metaphysical, theological, or aesthetic, can set a limit to the competency of science. But this limitless character, which science enjoys with respect to the quantitative aspects of reality, is also the source of its drastic limitedness….In other words, there is a most fundamental limit to a limitless science. Science has no limits whenever it finds—and in whatsoever form—material or material properties" (from The Limits of a Limitless Science).

The will is not itself a mathematical proposition, nor can it be quantified beyond such statements as a one-to-one ratio between people and their wills. Nor indeed can science explain fully while there is anything at all--though some attempts have been made to do just that. This is yet another of those ultimate final causes--indeed, the first among all final causes, and the last. Even a science so broad and fundamental as physics, which is ultimately the study of the very universe itself with all of its physical laws, cannot make accurate unaided declarations about things which are themselves beyond (or before) the universe. It would be wise, then, for those of us who are scientists to remember the words recorded by the prophet Isaiah: "For my thoughts are not your thoughts: nor your ways my ways, saith the Lord. For as the heavens are exalted above the earth, so are my ways exalted above your ways, and my thoughts above your thoughts" (Isaiah 55:8-9).