CHAPTER 6:
QUANTUM THEORY AND THE PHILOSOPHY OF NATURE

There are three main questions around which a dialogue between quantum theory and a Thomist philosophy of nature could coalesce: the epistemological type of modern physics, the principle of causality, and wholeness and nonlocality.

The Epistemological Type of Modern Physics

A Thomist philosopher of nature like Maritain would certainly have been pleased at the sound philosophical instincts that moved Bohm to avoid philosophical indeterminism as a direct consequence of quantum theory, and embrace a realism that believed in the existence of the objective world and our ability to know it. But our philosopher of nature would be somewhat dismayed to see how marginalized Bohm became because he acted on those instincts in regard to quantum theory. A belief in the objectivity of the world and our ability to know it, as well as causality, are all implicit in the work of the natural sciences. Without them science would not be possible. Why, then, would Bohm be isolated by his attachment to them?

Perhaps the answer lies in the fact that Bohm had a more developed philosophical sense than is common among physicists. From his early years he felt an intense desire not only to know the details about things, but he was fascinated with the question of wholeness. "I learned later that many of my fundamental interests were what other people called philosophical and that scientists tended to look down on philosophy as not being very serious. This created a problem for me, as I was never able to see any inherent separation between science and philosophy. Indeed in earlier times, science was called natural philosophy and this corresponded perfectly with the way I saw the whole field." (1)

When he worked later on electron plasma in which electrons seemed to exhibit a collective behavior, it was this wholeness with its similarity to living beings and society that interested him more than the formulas he developed. When he saw these formulas taken up and developed in an abstract way and the ideas behind them ignored, he lost interest in the field. He was to approach quantum theory in the same way. Even his textbook on quantum theory that followed Bohr showed a different attitude to doing physics. N never could think in terms of formalism. When I wrote my book on the quantum theory, I always worked out the results intuitively. I knew you had to put in a certain number of formulae between the beginning and the end, so I put them in. Though the results were always right, the formulae that I had put in between them were often wrong. I went over the book two times myself. A student went over it once, and still quite a few errors remained!" (2)

He realized that science among the Greeks had been largely speculative and had needed to be corrected by an emphasis on experimentation, but he felt that observations and their mathematical coordination now held sway to such a degree that philosophical insight that could give rise to experimentation was looked down upon. Physicists could give rein to their mathematical imagination, but not their philosophical one. (3)

Bohm, in one of the passages we have just seen, seems to identify physics with natural philosophy. This is an area to which Maritain devoted a great deal of energy, and he clarified the relationship between these two disciplines. We live in a world of concrete existing things, of trees and birds and stars, fire and ocean, and it is a world of constant change and interaction. Both the physicist and the philosopher of nature explore that world, the world of the physically or sensibly real, but each in a distinctive way. It is an understanding of the distinctiveness of these ways that has the power to resolve the conflict that has raged between the sciences and philosophy and religion for the last 300 years, and Maritain excelled at that kind of epistemological analysis.

He starts his analysis by summarizing the Aristotelian-Thomistic tradition of the three degrees of abstraction, or put in more modern terms, the three fundamental ways in which the mind can carve out intelligible cross-sections in actually existing things. Let's imagine I have a steel ball bearing in my hand. If I were a mathematician I could abstract from the fact of its matter and focus on its spherical shape and its properties even though that sphere could only actually be realized in some concrete existing thing. If I were a metaphysician, I might abstract from matter completely and simply consider the primordial fact that this certain kind of thing exists. But both the philosopher of nature and the physicist would look at the ball bearing as part of the world of the sensible real, as an object that falls under our senses and is subject to motion and change. They wouldn't look at it as this particular concretely existing steel ball bearing. They would abstract from its individual matter. But each of them would cut a different intelligible cross section. The physicist looks at the world of the sensible real inasmuch as it is measurable. The philosopher of nature looks at that same world, but tries to fathom its deepest nature. If the physicist would drop the ball bearing out the window, he or she would then be caught up in discovering the law of the motion of falling bodies. The philosopher of nature, in contrast, would be trying to discover the nature of change in terms of potency and act.

In Aristotle the philosophy of nature embraced what we call today both natural philosophy and physics. It tried to be at once an examination of the basic principles of nature and of phenomena, and in this it failed. The newly emergent sciences of nature had to discover their own distinctive ways of proceeding. They broke with the old philosophy of nature and allied themselves to mathematics. In this way physics became a genuine science of phenomena, but it also believed that it had no longer any need of a philosophy of nature, or even it, itself, was a philosophy of nature.

Let's look at this issue in a more nuanced and detailed way by examining Maritain's masterpiece, The Degrees of Knowledge. The alliance of physics with mathematics instead of philosophy Maritain ranks as one of the great discoveries of modern times. Physics is "materially physical and formally mathematical." (4) Physics both starts and ends in the physically real, but submits the measurements it has drawn from the physical world to the rule of mathematics.

But if natural philosophy had to learn that its domain did not extend to the phenomenon of nature, physics has its own difficult lesson to learn. The method it uses to capture phenomena does not touch the inner nature of things. "It grasps the essence in a substitute which is scientific law..." (5) It is certainly founded on the stable ontological core of things, but it grasps it blindly in a web of measurements submitted to the formal rule of mathematics. It is a true and valuable knowledge of the physically real, for both its measurements and the mathematics it uses are derived from that real world, but it doesn't yield a direct insight into the underlying ontological structure of things. It presupposes that there are stable structures that give rise to universally valid scientific laws.

But if this is true, then "a physico-mathematical theory will be called "true" when a coherent and fullest possible system of mathematical symbols and the explanatory entities it organizes coincides, throughout all its numerical conclusions, with measurements we have made upon the real; but it is in no wise necessary that any physical reality, any particular nature, or any ontological law in the world of bodies, correspond determinately to each of the symbols and mathematical entities in question." (6)

This is a statement of the highest importance if we are ever going to unravel the philosophical issues that surround quantum theory. There is no way in which we can establish a one-to-one correspondence so that each mathematical symbol corresponds to a certain physical reality. Therefore, it becomes extremely difficult to discover the philosophical implications of something like quantum theory which takes such a highly mathematical form. If this knowledge of a physico-mathematical kind were erected into a philosophy of nature, we would be left in a state of serious confusion, as has happened in the case of the Copenhagen interpretation.

This is a very difficult and delicate issue. It would be completely wrong to imagine that physics doesn't deal with the sensible real and come to a true knowledge of it. Yet, without an understanding of its epistemological type we are very liable to misconstrue what it tells us. Physicists, like the rest of us, have a desire to understand the inner nature of things, and this thirst can generate certain explanations of the physical world based on the results of physics but without a clear awareness that these explanations are only indirectly rooted in physical reality. It is enough that the physics is good for the explanatory picture constructed upon it to satisfy the physicist's implicit ontological thirst. These imaginative reconstructions of the physical world then find a more general audience that uncritically accepts them as the way the world actually is. Then we are left with the impression that the real world is based on the non-causal world of microphysics, or that real space and time are like the space and time that Einstein described. But the intelligible cross-section that physics takes out of concrete existing things embraces only one aspect of reality. Neither its physico-mathematical constructs nor the explanations built on them have a direct ontological value.

The old philosophy of nature could only purify itself if it admitted it was blind when it came to the study of natural phenomenon. The new physics is equally powerless when it comes to the inner nature of things, but it has been as reluctant to admit its limitations as the old philosophy of nature was. "The physicist wishes to penetrate the secrets of matter; but the very type of knowledge to which he is bound prohibits him from attaining the nature of matter in itself. He attains it in the observable and measurable, and thereby real, determinations which are for him the substitutes for the essence, and he scrutinizes it and fathoms it to the very degree that he mathematically symbolizes it." (7)

There is no way for physicists to fully satisfy their ontological thirst if they believe that there is no other way to know nature than by the method of physics itself. But if the philosophy of nature is not another physics or some pale appendage that follows in the wake of the natural sciences, then what is it? It is a science not of the phenomenon of nature, but its constitutive principles. "For example, it belongs to the Philosophy of Nature to instruct us about the nature of the continuum and of number, of quantity, of space, of motion, of time, of corporeal substance, of transitive action, of vegetative and sensitive life, of the soul and its operative powers, etc." (8) This philosophy of nature must receive scientific facts from the natural sciences, but not uncritically. It needs to bring to bear on them its own distinctive philosophical light in order to draw out their ontological implications.

How does all this work out in practice? Let's briefly look at some concrete cases.

Relativity and the Philosophy of Nature

If Einstein possessed some of the same instinctive realism that we have admired in Bohm, that doesn't mean we should take his theory of relativity as a description of how the world actually is in itself. Or put in the terms we have just been seeing, relativity, while it is based on physical measurements and leads to successful predictions, does not coincide in the formal mathematical structures and symbols that it creates with things taken from an ontological point of view. That simply is not the concern of the physicist. But physicists, because of their thirst for deeper and more universal ways of explaining the world, are prone to interpret their physico-mathematical. constructs as depictions of what reality in itself is like, and in this Einstein was no exception.

Maritain listened to Einstein address French philosophers in Paris in 1922, and he was struck by the fact that when Einstein spoke about simultaneity it was always in direct relationship to what simultaneity should mean to a physicist and how it could be measured. The notions of simultaneity, as well as space and time, are recast according to the demands of measurement and mathematical organization. There is no explicit metaphysical questioning going on here, nor should there be. But the vital question is whether the space-time of Einstein, or the fabric of the universe curved by the mass of the objects in it, or the uniform velocity of light, no matter what its frame of reference, or the shrinking of measuring rods and the slowing of time, describes the universe as it actually is. Certainly we have been led to believe they do, and we struggle with the paradox of the astronaut leaving earth for what appears to be two years, and coming back to discover all his family and friends long dead. Philosophers and theologians are urged to take these results of modern science and update their own disciplines. But what if Maritain is correct? What if these images we take for the way reality is must be subjected to a very searching philosophical analysis before they yield up their ontological content?

Maritain, in a long article on simultaneity according to Einstein, points out the kind of metaphysical confusion that results if we confuse the findings of physics with the ontological nature of the world. (9) Einstein's simultaneity, which he demonstrates to be relative, is not the same as real simultaneity in the philosophical sense. Two events from a philosophical point of view are either simultaneous or they are not. They either happen at the same instant or they do not. They cannot both happen and not happen at the same moment no matter what their frames of references are.

We may construct a situation, as Einstein does with his famous example of the observer on the train and the observer on the right-of-way, both trying to decide if two events are simultaneous, and from that example conclude to the relativity of simultaneity. But this is simultaneity as measured which is the only thing that the physicist is interested in, and it does not have any ontological content despite the fact that Einstein implied that it did.

The Copenhagen Interpretation

Maritain has left us, as well, with some suggestive remarks on quantum theory even though he did not devote the attention to it that he did to relativity. Quantum theory clearly illustrates the emergence of physic's distinctive epistemological type. In fact, it represents one of the limiting cases of that type because of the dominance of mathematical symbols which do not readily lend themselves to causal explanations. The creators of quantum theory, themselves, were at a loss of how to interpret their own discoveries. As Bohm points out, the so-called Copenhagen interpretation actually is a bundle of allied interpretations with significant differences between them, and a definitive interpretation of the quantum formalism has yet to appear.

But Maritain realized that the mathematical symbols of quantum theory "are just awaiting a chance to leave the realm of pure analytical form and become explanatory entities." (10) And these explanatory entities have to be carefully examined from a philosophical point of view in order to discover their ontological content.

When Maritain looked at quantum theory around 1930 when he was preparing his Degrees of Knowledge, de Broglie had already given up his causal theory and accepted the dominance of the Copenhagen school. This loss of causality did not bother Maritain as such because he saw it as a direct result of the increasingly physico-mathematical structure of physics. Physics has the right to create a non-determinist view of microphysics and to look at quantum waves as waves of probability as long as it doesn't give these constructs a philosophical interpretation. Maritain felt there was no need to hope with Einstein that strict causality would regain the upper hand. If the old physics tended to lend its authority to a philosophically determinist view of the world, the new physics could be as indeterminist as it wanted as long as it realized the nature of the results it had achieved and refrained from giving them a philosophical meaning. For Maritain our inability to know the precise position and velocity of a particle stemmed from the disturbances our measurements create. It is not the place of physics to elevate this fact into a philosophical conclusion that speaks of the indeterminacy of nature itself, but this is the kind of self-discipline that comes hard to physicists. Maritain saw the possibility that the new physics of 1930 will give rise to an inchoate philosophy. "Doubtless public opinion will be stirred up by a prejudice in favour of contingency and liberty only by casting doubt on the substantiality of matter and the principle of causality." (11) And public opinion certainly was stimulated by the philosophical baggage that came with the Copenhagen interpretation: the indeterminate nature of the quantum world, events happening without causes, observer-created reality, and so forth. Here we are back to the delicate problem that Maritain has been grappling with. It is all well and good and even necessary to distinguish the physico-mathematical theory of quantum mechanics from its interpretation, but physicists are driven almost irresistibly to interpret it, for they want to know, despite Bohr, what nature is like. Put in another way, physics can't rest content in understanding itself in a minimalist positivistic fashion. But if we can't erect a philosophy directly on its findings, where does that leave us? The only way to explore the ontological meaning of physics is through a genuine philosophy of nature which would enter into a profound dialogue with it.

Bohm's Causal Interpretation

There are some important philosophical lessons to be drawn from Bohm's causal interpretation. It makes abundantly clear that the quantum formalism does not have to be interpreted in an indeterminate sense. This alone is of great importance because it allows philosophers and theologians a chance to avoid the metaphysical confusion that would result if they felt constrained to believe that quantum theory had demonstrated philosophical noncausality.

It might be objected that we have been attracted to Bohm all along precisely inasmuch as he is a philosopher of nature rather than a physicist. This objection ought to be taken seriously because it can teach us something valuable about the dialogue between the philosophy of nature and the natural sciences that we are suggesting.

We would be wrong to simply characterize Bohm as a philosopher of nature because this wouldn't explain his well-admired work in fields like electron plasma and the Bohm-Aharanov effect, not to mention his quantum theory textbook. As strange as it may seem, what interests a philosopher of nature about Bohm's work is not those moments where he tries to be the most philosophical with his talk of the holomovement, society and noetic fragmentation, consciousness, etc. I am not denying that philosophers and theologians could profit by a careful examination of these ideas, as well as find any number of points they would like to clarify or criticize, but what most fascinates the philosopher of nature are those places where Bohm's philosophical instincts are in direct contact with scientific questions like the interpretation of quantum theory, and remain anchored there. There is, we could say, a zone of interaction between quantum theory and Bohm's instincts for a philosophy of nature that are the most fruitful areas for us to explore.

Bohm published his initial papers on the causal interpretation in 1952, as we have seen. "Because the response to these ideas was so limited, and because I did not see clearly at the time how to proceed further, my interests began to turn in other directions." (12) In the 1960s he turned to questions about order and language and their relationship to doing physics. This led him to see the importance of the drops of ink in the cylinders and holograms as examples of enfolding and unfolding and their possible application to quantum theory. From there it was only a step to generalize this movement from the implicit to the explicit and arrive at the idea of the holomovement. The holomovement, in a reversal of our usual perspective, becomes primary and the stable forms of our experience become expressions of it. This insight pleased Bohm, for such a theory would put some philosophical ground under the idea of wholeness that he had encountered in the form of the quantum potential.

But to illustrate the zone of interaction I spoke of a moment ago, it is not the holomovement in its universal form that most interests the philosopher of nature, but the ideas of wholeness and nonlocality as they directly emerge out of Bohm's causal interpretation. Bohm's intellectual trajectory illustrates an important point. After his insight that led to the 1952 papers he didn't know how to develop his ideas on quantum theory further. His excursion into the realm of philosophy stimulated the creative process and allowed him to look at quantum theory fruitfully again. This kind of interaction was present up until his final book and is worth reflecting upon. It gives us a very different picture than one in which Bohm is incessantly tinkering with the formal presentation of his quantum theory in order to meet various objections. His philosophical excursion gave birth to new insights which he then explored and tested in the context of his physics. But no matter how useful this process might have been in forming Bohm's creative interpretation, it doesn't mean that philosophers of nature ought to focus on the holomovement. As a purely philosophical idea, in fact, it poses any number of difficulties: the primacy given to movement, the denial of direct causation as particles appear and disappear into the implicate order, the infinite series of implicate and explicate orders, etc. (13)

The implicate order is a philosophical attempt on Bohm's part to understand the wholeness and nonlocality that his causal interpretation seems to demand. For the philosopher of nature the scientific fact of wholeness and nonlocality is much more fascinating than Bohm's particular philosophical reflections on it. We will return to this issue in a little while.

What can we say about Bohm's work? We have already seen that Bohm was not only a physicist, but he was also gifted with some of the instincts of a philosopher of nature. Even in his physics he was not attracted to mathematics with the intensity that it draws many of his fellow physicists. Let us say he experienced the strong pull of a philosophy of nature, and since no philosophy of nature was visible on the horizon he set about creating his own. In this way he brought about within himself the very dialogue between physics and natural philosophy that we have been suggesting. This dialogue, far from being detrimental to his physics, he felt inspired it, and vice versa, and his inchoate philosophy of nature provided a nurturing matrix for the development of the causal theory. This fact, of course, does not in itself validate either side of the dialogue that took place within Bohm. His physics can be wrong, and his philosophy of nature, as well, but it does point to an important conclusion. If a genuine philosophy of nature is reborn, it will not be to the detriment of physics, but to its benefit, and to its own.

Causality and Quantum Theory

Bohm has certainly made the life of a Thomist philosopher of nature much easier. Imagine if she or he were faced with the unanimous opinion of physicists that causality does not hold sway at the quantum level. The alternative interpretations of quantum theory are not very promising to the Thomist eye whether it is the case of a quantum logic at odds with our normal one, or a world in which consciousness creates reality, or a many worlds approach in which each collapse of the wave function creates a new universe and observers to inhabit it.

But even the Copenhagen interpretation in its various permutations is not palatable, and we owe some of the most trenchant criticisms of it to Bohm. He took pains to point out that the development of a causal theory of quantum mechanics was hindered not only by the complexity of the physics involved, but by philosophical considerations, as well. Heisenberg's indeterminacy principle was not seen as flowing from the current state of quantum theory, and thus changeable as the theory evolved and developed, but was erected into a universal law of nature which could not be surpassed. (14) Thus, any hidden variable theory was automatically ruled out because these variables could not be known. It is not a question of our ignorance that may one day be remedied, but the fact that nature, itself, is indeterminate, and yet gives rise to the determinate events of our experience. "Real and observable physical phenomena are being assumed to have no causes." (15)

The individual click of the Geiger counter is caused by the disintegration of a particle which has no cause for its disintegration. The statistical nature of quantum theory is no longer in continuity with classical statistics, for classical statistics rests on complex interacting causal trajectories that we cannot decipher in detail, but which are decipherable in principle, while quantum statistics rests on no such causes.

It is Bohm's contention that these kinds of philosophical consequences do not inevitably flow from either the experimental facts or the mathematics of quantum theory itself. This conclusion alone is worth its weight in gold to the Thomist philosopher of nature who can then avoid to bring philosophy and then theology into line with what is not good physics, but bad philosophy. Unfortunately, the philosophy that surrounds the Copenhagen interpretation has by a certain cultural osmosis pervaded many other fields, and it is rather common to hear asserted the unexamined assumption that the principle of causality has failed, and we need to realign our thinking accordingly. This general atmosphere makes it difficult for philosophers and theologians to seriously contemplate the possibility that philosophical noncausality in the quantum realm simply does not exist. Several examples will illustrate the difficulty of coming to such a judgment.

In a conference on science and consciousness held in Cordoba, Spain, David Miller - of Hillman style Jungian psychology fame - summed up what he felt was the cultural heritage of quantum theory and the new physics. This new way of thinking: "(1) blurred the distinction between organic and inorganic, (2) showed the notion of causality to be of limited value ("Events do not develop", writes Zukav), (3) implied that "field" is more important to consciousness than is "matter", (4) dispensed with the Aristotelian idea of "non-contradiction", (5) dislocated the concept of the distinguishability of subject and object ("How can we know the dancer from the dance", writes Yeats), (6) noted that probability or tendency to exist is a more useful way of imagining things than is that of discrete quantity or existence of solid object, and (7) hinted that a sort of "consciousness" is attributable to quantum phenomena which seem to make "decisions" or "know" what is happening elsewhere." (16)

I would be surprised if either he or the audience was prepared for the response of J.P. Vigier, a colleague of both Bohm and de Broglie in the formation of the causal interpretation who said, "Unfortunately I am in complete disagreement with all that Mr. Miller has said... The ultimate issue in this debate is the very existence of matter and the objectivity of things." (17) In another intervention during the conference he stated, "I feel, however, that it is much too soon to bury Einstein's materialism and determinism. By materialism I mean simply the objective existence of phenomena, independently of any observation. I assure you that if I leave this room I shall continue to exist even though you cannot see me. As to causality, I am absolutely convinced that the order of cause and effect cannot be altered, and you will allow me to await conclusive experiments to the contrary, checked and verified, before I abandon this idea." (18)

Given what is at stake, we could imagine that philosophers and theologians would be inclined to favor Bohm's point of view rather than the Copenhagen interpretation. But this does not seem to be the case. Christopher Mooney in "Theology and the Heisenberg Uncertainty Principle" feels that theologians have not come to terms with quantum theory. "Relatively few have been willing to familiarize themselves with the anomalies of quantum reality, or to grapple with their revolutionary implications for understanding divine grace and human freedom, God's creative action in the world, and indeed the doctrine of God itself." (19)

In order to avoid his own strictures, he goes on to give an excellent summary of the history of quantum mechanics and its various interpretations, and this only whets our appetite to know what these revolutionary implications are. Unfortunately, his final section comes as a disappointment. He decides not to follow Bohm because Bohm denies "the ontologically open character of quantum entities." (20) But this is a fateful choice that seems to yield little that is truly revolutionary. Mooney will end up patterning God's action in the quantum world after the model of God's action in the realm of human freedom. Somehow God exercises a "voluntary self-limitation" in regard to matter. "From this perspective the vulnerability of the divine Word in history would be a reflection of a certain precariousness in the creative process itself, and the indeterminacy of quantum reality would illustrate this divine patience at matter's roots. Because God relates to every creature according to its nature, these roots would be allowed to explore their own potential, because matter's nature, like freedom's nature, is to do precisely this." (21)

But this does not really engage the truly revolutionary implications that would exist if we took the philosophy of the Copenhagen interpretation seriously. Just how does God create and sustain matter in existence if the realm of matter is literally a place where causality does not function? Just what metaphysical sense can we make out of something -that is so ontologically open as to have no cause?

If someone like Mooney who had devoted considerable energy to mastering the history and interpretation of quantum theory failed to come up with a rich philosophical and theological harvest in relationship to the Copenhagen theory, we can begin to wonder if it can really be done. A possible rejoinder is a point we touched on before. Choosing Bohm is choosing the easy way out, and he has little acceptance among physicists. This would certainly be a problem if Bohm's work was a marginal enterprise that had bloomed briefly in the 1950s and then faded away because it was bad physics, and we were dragging it out in order to bolster outmoded ideas on physical causality.

In actual fact Bohm continued to strengthen his interpretation until the end of his life, as we have seen, and as his Undivided Universe demonstrates. Nor can the strong support that he received from Bell and the role that his work played in the development of Bell's theorem be overlooked. Is Bohm's work really on the way out? That is for physicists to decide. But the 1993 appearance of Peter Holland's The Quantum Theory of Motion: An Account of the de Broglie - Bohm Causal Interpretation of Quantum Mechanics, and the resurgence of interest in nonlocality would make it rash to discount Bohm's work too quickly.

Holland's Quantum Theory of Motion shows the same kind of iconoclastic rigor that we saw in Bohm as it extends his scientific work to new areas. A few examples will suffice. We need not remain satisfied with an account of quantum theory that "contains no account of the constitution and structure of matter" (22) or a theory that demands wave or particle instead of wave and particle. The de Broglie - Bohm theory aims at "a complete description of an individual real situation as it exists independently of acts of observation." (23) There is an "unspoken contradiction at the heart of quantum physics: physicists do want to find out 'how nature is' and feel they are doing this with quantum mechanics, yet the official view which most workers claim to follow rules out the attempt as meaningless!" (24) The wave function need not be interpreted exclusively in a probabilistic way. "On the contrary, one may take the view that the characteristic distribution of spots on a screen which build up an interference pattern is evidence that the wave function indeed has a more potent physical role than a mere repository of information on probabilities, for how are the particles guided so that statistically they fall into such a pattern?" (25)

Bohm at the very beginning of Causality and Chance in Modern Physics gives us a way to return to and to intensify our dialogue on causality.

"In nature nothing remains constant. Everything is in a perpetual state of transformation, motion, and change. However, we discover that nothing simply surges up out of nothing without having antecedents that existed before... everything comes from other things and gives rise to other things.

"This principle is not yet a statement of the existence of causality in nature. Indeed, it is even more fundamental than is causality, for it is at the foundation of the possibility of our understanding nature in a rational way.

"To come to causality, the next step is then to note that as we study processes taking place under a wide range of conditions, we discover that inside of all of the complexity of change and transformation there are relationships that remain effectively constant... we interpret this constancy as signifying that such relationships are necessary, in the sense that they could not be otherwise, because they are inherent and essential aspects of what things are. The necessary relationships between objects, events, conditions, or other things at a given time and those at later times are then termed causal laws.

"At this point, however, we meet a new problem. For the necessity of a causal law is never absolute. For example, let us consider the law that an object released in mid-air will fall. This in fact is usually what happens. But if the object is a piece of paper, and if "by chance" there is a strong breeze blowing, it may rise. Thus, we see that one must conceive of the law of nature as necessary only if one abstracts from contingencies, representing essentially independent factors which may exist outside the scope of things that can be treated by the laws under consideration, and which do not follow necessarily from anything that may be specified under the context of these laws. Such contingencies lead to chance." (26)

In this dense statement Bohm touches on many of the principles that are at the heart of a Thomist philosophy of nature. For the philosopher of nature the world of nature is the world of mobile or mutable beings. "Nothing simply surges out of nothing" is an expression of the philosophical principle of sufficient reason. "Everything which is, to the extent to which it is, possesses a sufficient reason for its being." (27) If we were to deny this principle, we would violate the still more fundamental principle of identity in which we affirm that each being is what it is, that it possesses existence which maintains it outside of nothingness, that being and nothingness cannot be identified.

Mutable being is contingent being. It does not have to be what it is. It can come into existence and go out of it. "Every contingent being has a ground other than itself, exterior to itself, that is to say an efficient cause." (28) If the scientist will discover in change necessary relationships that are somehow related to the "inherent and essential aspects of what things are" the philosopher of nature will try to fathom these inherent and essential aspects of what things are, or in philosophical terms, their essences or natures more directly. There is only science of the necessary. Science is certain knowledge through causes, as the ancients put it, and this is true whether we are considering physics or the philosophy of nature. But this strong view of causality never gave rise to philosophical mechanism. It was recognized that our sciences were abstractions that cut different intelligible cross-sections out of actually existing things, and these things in themselves were much richer than the concepts we tried to capture them in. The world could never be reduced to points and lines of force connecting them. It was a world of contingency and chance, mystery and adventure.

Let's look at the case of radioactive decay from the perspective of a Thomist view of causality. The Copenhagen school will talk about individual quantum events as being "radically uncaused." (29) Even though the half-life of the radioactive element can be determined, nothing determines when a particular atom will disintegrate even though we can register the individual decay event on our Geiger counter. The decay of this or that particular atom is literally uncaused. What can a Thomist philosopher of nature make out of this? The particle, given off by the decay of the atom, is a contingent being, a being that is subject to change, that does not have to be what it is. Whatever is contingent is caused, that is, has "a ground, a sufficient reason other than itself." "Every contingent being has a ground other than itself, exterior to itself, that is to say an efficient cause." (30) No one would deny that the particle came to be out of the decay of the atom, but if it came to be, it did not have its own ground of being in itself. But then it has its ground outside itself which is the very notion of being caused.

This might be more readily graspable in terms of potency and act. An acorn sprouts and becomes an oak tree, so we can say the acorn possessed the potency or capacity to become that oak. Potency, then, is a certain capacity for becoming what actually is. Potency cannot be understood outside of the context of what actually is or act. Potency is the capacity of some act for further act. It never stands alone. There cannot be a pure potency that actually exists. An equivalent way of stating it is that there cannot be a pure indeterminacy. All indeterminacy is a particular capacity for act and is measured by that act. The acorn has a very definite indeterminacy. It won't turn into a canary or an elephant, and this indeterminacy is rooted in the determinacy of the existing acorn. To return to the question of efficient cause we can say "That every being compounded of potency and act, inasmuch as it is potential does not pass of itself to act, does not reduce itself to act. It passes to act by the operation of another being in act which causes the change." (31)

In the case of a radioactive atom which decays we can say it had the capacity to decay, the potency or indeterminacy to release the particle, but that this capacity cannot reduce itself to act. If it could, it would be at once in act and in potency. It would give itself the very being it does not have. So from a Thomist point of view to say that the event is radically uncaused is to say that the atom somehow picks itself up by its bootstraps and gives itself what it does not have, that being somehow comes out of nothingness.

But if causality holds sway in the microworld even though physicists cannot measure it, then the statistics of that world do not differ in essence from those of the ordinary world, nor are we faced with trying to explain how a radical lack of causality gives rise to a world in which causality reigns.

It is also important to distinguish this view of potency and act from that of Heisenberg who also made use of these Aristotelian concepts, but transformed them to suit his own purpose. For Heisenberg the denizens of the quantum world possess ranges of potentialities, or tendencies to exist which have a strange kind of reality in the middle between possibility and actuality. (32) But from a Thomist point of view potency cannot exist except in relationship to act. There can be no potency floating around by itself. It is entirely possible that the inhabitants of the quantum world possess more potency than other beings, but their potency must be anchored in act, that is, in an actual being with a determinate nature, and therefore their potency is of a very definite sort.

This defense of causality is entirely compatible with a view of the world in which chance plays a large part, but chance in the Thomist view rests on causality. It is the intersection of different causal chains of events. I am driving to the supermarket because my wife has decided that she wants to have spaghetti for dinner, and she has discovered that the last time at the store she has forgotten to buy the sauce. At an intersection a car comes through a red light and bangs my fender because its driver was distracted by a small boy who ran out into the street to get his ball. There is nothing in either chain of events that is uncaused, but the intersection of these two chains does not have a cause in the usual sense of the term. "That is to say there is no nature, no natural agent predetermined by its structure to this encounter... nor any created intelligence that designed it." (33) Chance comes about because of the genuine causality that things exercise. It is not predetermined by those things, but neither can it be at the origin of things for it presupposes the causal chains that interact.

We can sum up some of the themes we have seen in these last two sections dealing with the epistemological type of physics and the question of causality by looking at an article by Robert John Russells who is both a physicist and theologian, called "Quantum Physics in Philosophical and Theological Perspective." His method is to "use philosophy as a bridge between physics and theology, in particular focusing on a philosophy of nature informed by quantum physics and addressing questions both to metaphorical and systematic theology." (34) This methodology highlights the pivotal role that a philosophy of nature is called to play in the dialogue between physics and theology, but as Russell proceeds, he runs into the same difficulty that we saw in Mooney because he, too, tries to draw philosophical implications from the Copenhagen interpretation.

Russell makes some interesting remarks about the epistemological nature of quantum physics. "What seems to be coming under increasing pressure, at least in the realm of quantum physics (and, I would argue, in cosmology as well), is the further and more specific claim of correspondence, that the structure of the theoretical concepts corresponds to some extent with the structure of their references in nature. Also being challenged by quantum physics, in my opinion, is the claim of convergence, that the sequence of these terms generated by successive theories stand in increasingly more accurate correspondence to these structures. For it is above all true that in quantum physics "picturability" breaks down (though not, I would agree, referentiality in a broader sense). We surely believe there is something "out there" and that we are in some sense gaining a more complete understanding of it as we gain more increasing predictive accuracy through successive theories. However our ability to think up an ontology for what's "out there" is now under serious and sustained attack." (35)

Maritain's analysis of the epistemological type of modern physics is compatible with a loss of correspondence and convergence. But in his mind there is no way that an ontology can directly emerge from quantum physics. The very lack of physical correspondence and convergence with nature prevents this from happening. When Russell writes, "Suddenly atoms literally at random begin to decay. Each event is, as far as we can tell, without cause," (36) we can understand this statement in two different ways. If it is a question of the epistemological limits of modern physics, then "without cause" means unable to be measured by physics' current methods. But if "without cause" is a philosophical statement, then there is little wonder that a coherent philosophy cannot be built upon it. But if no genuine philosophy of nature develops, then the theological implications of quantum theory will remain undeveloped, as well. Russell suggests that the indeterminacy of the quantum world can remind us of the working of divine providence, or that nonlocality and the wholeness it implies is a metaphor for inter-religious unity, or the complementarity that Bohr speaks of might be analogously found in theology. But all these suggestions will remain no more than that because there is no philosophy of nature.

There is certainly something very fascinating about the quantum world, but this is not a lack of causality, but nonlocality and wholeness. It is only if we were to identify all causality with efficient causality that we would feel compelled to state that causality has failed in the quantum world. This brings us to the third basic issue in the dialogue between quantum theory and a Thomist philosophy of nature.

Wholeness and Nonlocality

While John Bell did not possess the explicit philosophical interests of Bohm, he did share some of his sound philosophical instincts. As a student he went through a philosophical period asking, "How do we know the world is really there?" and what he called other "standard questions."

"I very soon found that what one had said was contradicted by another. Philosophy was very frustrating, and physics was the next best thing. You could come to reasonably certain conclusions in physics, whereas you could not in philosophy." (37)

But the instincts that prompted this foray into philosophy expressed themselves in his scientific work in a variety of ways: a dissatisfaction with the conventional interpretation of quantum mechanics, an admiration for Einstein's idea of what physics was all about, an interest in Bohm's initial papers on the causal theory, and a fascination with the measurement problem in terms of where the dividing line between the quantum world and the world of our experience should be placed, and these interests were to play a role in the creation of his famous theorem. This same attitude also allowed him to take a remarkably positive view of Bohm's work and to try to call attention to it in various articles, and perhaps this sense of realism added some extra enthusiasm to his demolishing of von Neumann's proof.

When asked whether he thought that the fact of nonlocality had been established he replied, "Yes. But I don't know what it means. That is to say, Einstein's locality is disestablished, but we have not put anything in its place. To say that 'locality is dead; therefore we must believe in nonlocality,' is already to say something too positive." (38)

Bell attempted to explain this nonlocality in lay terms by using the example of identical human twins reared apart. When we find that a pair of identical twins reared apart look alike, we ascribe it to genetics. In physics when we ask twin photons the same question, and they answer it in the same way, we are led to believe that they were predetermined to have that answer before we questioned them. But human twins reared apart sometimes exhibit traits that seem to defy a purely genetic explanation. They may both like the same kind of automobile, or give their dogs the same name. Could there be some other kind of force, some form of telepathy, that would account for this? In physics the idea of predetermination breaks down when we ask the twin photons different questions, and we are led to the idea that our questioning of the one photon has, despite its distance from the other, effected the other photon. (39)

When Bell destroyed von Neumann's proof ruling out hidden variables, he discovered that any hidden variable theory had to be nonlocal. By locality he meant "the idea that what you do has consequences only nearby, and that any consequences at a distant place will be weaker and will arrive there only after the time permitted by the velocity of light"' (40) And Bell's theorem "tells you that maybe there must be something happening faster than light, although it pains me even to say that much. The theorem certainly implies that Einstein's concept of space and time, neatly divided up into separate regions by light velocity, is not tenable. But then, to say that there's something going faster than light is to say more than I know." (41)

Experiments, as we have seen, seem to indicate that Bell's theorem is correct, and local realism theories must be discarded. But local realism is composed of a number of different elements. Bernard d'Espagnat, in a very well-reasoned article, "The Quantum Theory and Reality," describes them like this: "One is realism, the doctrine that regularities in observed phenomena are caused by some physical reality whose existence is independent of human observers. The second premise holds that inductive inference is a valid mode of reasoning and can be applied freely, so that legitimate conclusions can be drawn from consistent observations. The third premise is called Einstein separability or Einstein locality, and it states that no influence of any kind can propagate faster than the speed of light." (42)

If something has to go, what will it be? Scientists in their work and all of us in practice are implicitly realistic. There is a world out there, and it doesn't depend on my observations of it in order to exist. If we gave up realism for a shallow positivism we would have little left. If we gave up inductive reasoning, we would be in no better shape, for it, too, is founded on a realistic view of the world and the existence of universally valid scientific laws which in turn rest on stable natures. That leaves Einstein's locality.

Bohm in his Wholeness and the Implicate Order tries to understand the kind of nonlocality that would replace Einstein's separability. We have already briefly seen his examples of revolving cylinders and the hologram with which he illustrated the relationship between the implicate and explicate orders, and he has another useful example, as well. Two television cameras are focused on adjacent sides of an aquarium that has fish swimming in it, and therefore, the two television pictures they produce of the swimming fish are correlated. Instead of saying there is a causal connection between these two images, it would be better to say that the two two-dimensional images are projections of a higher three-dimensional reality. If we transfer this imagery to the experiments that have demonstrated nonlocality, each particle can be thought of as a projection of a higher dimensional reality. There is a correlation between the particles, but of a "non-causal" sort, for they are not directly interacting with each other. Put in another way, we can say that there is no efficient causality operating between them, and no need to make some force travel faster than the speed of light from one to the other in order to effect the correlation observed. The correlation comes from somewhere else - a higher dimensional reality.

Bohm will spend considerable effort in this book trying to fathom what that higher dimensional reality could be, and in doing so he will travel a considerable distance from that zone of attraction where his philosophical instincts are directly engaged in physical problems and come up with the holomovement which contains any number of philosophical difficulties. The higher dimensional reality, for example, is a process: "Not only is everything changing, but all is flux. That is to say, what is is the process of becoming itself, while all objects, events, entities, conditions, structures, etc., are forms that can be abstracted from this process." (43) Particles are continually unfolding and enfolding from the holomovement so there is no need to maintain their continual motion, or even their existence.

But there is no need to look at this attempt in detail. There is another way to approach an explanation of wholeness that is more compatible with a Thomist philosophy of nature, and Bohm gives us an important clue about it. He realized that for Aristotle causality meant more than just efficient or material causality. There was also formal and final causality, and Bohm picks out these kinds of causalities as akin to his implicate order.

"It is of crucial significance in this context to understand what was meant by formal cause. Unfortunately, in its modern connotation, the word 'formal' tends to refer to an outward form that is not very significant (e.g. as in 'formal dress' or 'a mere formality'). However, in the Ancient Greek philosophy, the word form meant, in the first instance, an inner forming activity which is the cause of the growth of things, and of the development and differentiation of their various essential forms. For example, in the case of an oak tree, what is indicated by the term 'formal cause' is the whole inner movement of sap, cell growth, articulation of branches, leaves, etc., which is characteristic of that kind of tree and different from that taking place in other kinds of trees. In more modern language, it would be better to describe this as formative cause, to emphasize that what is involved is not a mere form imposed from without, but rather an ordered and structured inner movement that is essential to what things are.

"Any such formative cause must evidently have an end or product, which is at least implicit. Thus, it is not possible to refer to the inner movement from the acorn giving rise to an oak tree, without simultaneously referring to the oak tree that is going to result from this movement. So formative cause always implies final cause." (44)

If explanations of nonlocality in terms of material and efficient causality break down, what would happen if we looked at the problem from the point of view of a Thomistic understanding of formal and final causality? This is a point we will have to return to later.