Quantum
“Causality” and Kantian “Quarks”
Everything in nature, as well in the inanimate as in the animated world,
happens or is done according to rules, though we do not always know them....
The exercise of our powers too takes place according to certain rules,
which we observe without a knowledge of them at first, till we attain it by degrees...
—Immanuel Kant[1]
1. Kantian
Causality and Quantum Quarks
When the unsuspecting student of quantum mechanics first reads Kant’s Critique of Pure Reason—or, when the unsuspecting Kant-scholar first learns about quantum mechanics —an apparent conflict immediately arises. For in the Analogies of Experience section of the Critique’s Analytic of Principles, Kant defends a set of three transcendental principles that explain how the category of relation is applied to the phenomenal world. The general principle covering all three analogies is: “Experience is possible only through the representation of a necessary connection of perceptions.”[2] The three subordinate analogies, specifying in more detail what is implied by the phrase “a necessary connection of perceptions”, are as follows:[3]
I. Permanence of Substance: “In all change of appearances substance is permanent; its quantum in nature is neither increased nor diminished.”
II. Succession in Time (= “Law of Causality”): “All alterations take place in conformity with the law of the connection of cause and effect.”
III. Coexistence (= “Law of Reciprocity or Community”): “All substances, in so far as they can be perceived to coexist in space, are in thoroughgoing reciprocity.”
The conflict arises because Kant argues in the second of the these analogies that all events happening in the empirical world must conform to the law of necessary connection. In other words, every event must have a cause. Yet, as we shall see, this assumption is just what standard interpretations of contemporary physics call into question. Kant says uncaused events do not happen; quantum mechanics says uncaused events do happen. Both statements cannot be true. Since quantum mechanics has achieved tangible results that nobody can deny, the sage of Königsberg must have been mistaken. And since the analogies are often regarded as the very heart of Kant’s entire philosophical project, the whole architecture of his System must now fall to pieces. This, at least, is the most common response to the apparent discrepancy between Kantian causality and quantum mechanics. In order to understand why it is quite mistaken, we must examine (in §2) the proper systematic context for interpreting Kant’s defense of the law of causality. Once the compatibility between quantum mechanics and Kant’s view of causality is brought into full view, we shall be in a position to appreciate (in §3) how an interesting form of quantum causality has Kantian roots that are often neglected. Finally, to confirm the depth of resonance between these two theoretical systems, we shall call attention (in §4) to a remarkable parallel between the physicists’ theory of quarks and the basic theoretical underpinnings of Kant’s System. Before doing any of this, however, let us first take a careful look at the essential features of quantum mechanics.
Quantum mechanics is a branch of theoretical physics concerned with understanding the characteristics and functions of the smallest of all objects in the empirical world: the “particles” that make up the atoms out of which the molecular structure of everything in nature is composed. The theories physicists have developed in order to explain the results of their subatomic experiments are often so strange that one well-known physicist, Richard Feynman, once admitted in a lecture: “I think I can safely say that nobody understands quantum mechanics”.[4] As we shall see, this is because both the theoretical presuppositions and the experimental results of quantum mechanics place limits on what we can observe and know about the world. Einstein’s relativity theory grew out of the insight that the speed of light serves as an upper limit for all physical interactions in the phenomenal world.[5] Quantum mechanics likewise grew out of the discovery of a corresponding lower limit, known as the “quantum of action”. Its numerical value was first calculated by Max Planck in 1900, so it is often called “Planck’s constant”.[6]
The word “quantum”, from which quantum mechanics derives its name, refers to the smallest observable unit of energy. When this microscopic “packet” of light, better known as the photon, interacts with electrons or other particles, it produces events that cannot be explained by the laws of classical physics. In the early decades of this century the physicists studying such events came to realize that the structure of the atom is not as simple as had for so long been assumed. The Greek word atomos means “indivisible”. But it turns out that a physical atom consists not merely of a heavy nucleus (neutrons and protons) with electrons orbiting around it, but also of smaller particles that hold together these basic parts. As far as we know, these subnuclear particles never spontaneously appear independently in nature; but they can be “generated” in high energy accelerators by causing photons to collide with stable particles in an atom. In this way a large number of mysterious, usually short-lived, particles—with exotic names like “muons”, “kaons”, “gluons”, and “cascade”—have been discovered to exist within the atom.[7] The most important of these new particles is called the “quark”.
Many physicists now believe all hadrons (i.e., all subatomic particles found in the nucleus of atoms) consist of quarks.[8] Hadrons come in two types: “mesons” are relatively light particles composed of a quark paired with an “antiquark”; and “baryons” are relatively heavy particles composed of three quarks. Particles such as protons and neutrons (the most familiar of all baryons) are now distinguished primarily by the differences in their underlying quark structure. Each quark has a fractional electrical charge of either 1/3 or 2/3 and is classified as either “up”, “down”, or “strange”.[9] The six resulting types of quark correspond to six types of leptons, which together form the twelve building-blocks of all matter.
This theory of quarks was first suggested in 1964 by Murray Gell-Mann and George Zweig, who won the 1967 Nobel Prize for their idea.[10] Postulating the existence of quarks soon proved to be a very effective tool for analyzing the data collected from subatomic experiments, even though there was at first no empirical evidence to support this hypothesis.[11] Finally, a series of experiments performed by a team of physicists at Stanford between 1967 and 1973 “produced convincing dynamical evidence from experiment for the existence of quarks”, earning the 1990 Nobel Prize for Jerome Friedman, Henry Kendall, and Richard Taylor.[12] Since then, even more conclusive evidence has been collected by various researchers about all but one of the twelve basic particles, until finally, evidence was announced several years ago indicating that even the elusive “top quark” also exists.[13] Just what implications can be drawn from such “evidence” regarding the real existence of quarks is, however, still a matter that is open to debate. Although some physicists speak somewhat carelessly as if quarks have actually been observed by the human eye,[14] this manner of speaking is technically inaccurate. Quarks have never actually been seen; at best physicists can see the effects quarks have on their super-sensitive measuring equipment. Moreover, in spite of all the evidence that has been collected through analyzing the results of experimental, high-energy collisions, none of this changes the fact that, because of the limits of observation imposed on us by light’s lower (quantum) limit, a quark could never be observed to exist on its own in nature. As recently as 1991, Smith expressed this point as follows: “quarks ... have never been observed as freely moving particles. There are strong reasons to believe that the nature of the forces which bind the quarks together, prevent their observations as freely-moving particles.”[15] For such reasons, the most prudent physicists recognize that the real existence of quarks is still very much an open question, and that the theory of quarks should properly be regarded as an hypothesis.
The experimental analysis of quantum data and the hypothetical explanation of how it all fits together have been quite distinct enterprises since the earliest days of quantum mechanics. The most widely accepted interpretation of quantum reality arose out of a series of conversations held during the winter of 1926-27, when the scientific world was still in the process of digesting the implications of Einstein’s theory of relativity, between Niels Bohr and Werner Heisenberg. Because they were in Copenhagen at the time, their explanation of quantum events came to be called “the Copenhagen interpretation”. For our purposes, the most significant aspect of the conceptual framework they constructed is that at the subatomic level, particles do not appear to be governed by the law of cause and effect. Quantum events, so the story goes, just happen. Moreover, in order to explain what happens, physicists are forced to use paradoxical language that would seem absurd if applied to the objects of our ordinary experience. For instance, when physicists cause two particles to collide with each other in a high energy accelerator, “they generally break into pieces, but these pieces are not smaller than the original particles.”[16] According to Herbert, if we could experience the quantum world in and of itself it would be a world characterized by non-Newtonian laws, a world of “undivided wholeness”, a “place without separation”, a “mystery” wherein the subject/object distinction itself dissolves, a world in which any perception “creates a new universe faster than light”.[17]
This Copenhagen interpretation of quantum mechanics rests on two important and interrelated pillars. The first is the hypothesis that the act of observing a subatomic particle actually affects it in some way. Quantum physicists insist that this renders them incapable of saying anything definite about the original (i.e., unobserved) state of a subatomic particle or event; all they can talk about is the nature of the particles as measured. The latter are therefore sometimes called “observables”, as opposed to the particles in their original, unobserved “state”. “The atomic and subatomic world itself lies beyond our sensory perception.”[18] The whole notion of an underlying, unknowable reality, whose existence can be inferred only from observations of the way it appears to us, is actually one of the fundamental tenets of Kant’s theoretical philosophy—though quantum physicists who wax philosophical are often as ignorant of this aspect of Kant’s philosophy as philosophers usually are of the mathematical apparatus used to describe quantum mechanics.[19] Quantum theory’s basic underlying distinction assumes a philosophical perspective akin to the transcendental, with its appearance/thing-in-itself distinction. Since “quantum reality” is physical, however, it obviously must be regarded as an empirical manifestation of this distinction.
The second pillar of the Copenhagen interpretation, generally known as Heisenberg’s “uncertainty principle”, provides the basis for this empirical distinction. It states that the scientist must choose between: (1) making a precise measurement of either the position or the velocity of a particle and leaving the one that is not measured completely unknown (and unknowable); or (2) attempting to measure both aspects at the same time and obtaining only an approximate knowledge of each in terms of statistical probability.[20] In other words, it is impossible to obtain certain knowledge of both the position and the velocity of a particle at the same time. This distinction between two ways of approaching the empirical task of measurement has a close affinity with Kant’s distinction between substance and accident (as stated in the first analogy, quoted at the beginning of this paper)—this being his way of making an empirical distinction between the knowable and unknowable. We shall examine this affinity in more detail in the following section. For now it will suffice to consider, as shown in Table 1, the four distinctions that result from comparing Kant’s epistemological version of the transcendental-empirical distinction with the physical version assumed by the Copenhagen interpretation of quantum mechanics.
Table 1: Four Ways of Distinguishing between the
Unknowable and the Knowable
2. The Law of Causality in Perspective
The inference most commonly drawn from Heisenberg’s uncertainty principle is that the familiar law of causality is mistaken, and must be abandoned. Physicists believe, for example, that
... atoms [may switch] suddenly from one ‘quantum state’ to another ...[21]
Subatomic particles do not exist with certainty at definite places, but rather show ‘tendencies to exist’, and atomic events do not occur with certainty at definite times and in definite ways, but rather show ‘tendencies to occur’...[22]
In quantum theory individual events do not always have a well-defined cause. For example, the jump of an electron ... may occur spontaneously without any single event causing it.[23]
Moreover, describing quantum events often requires physicists to make explicitly self-contradictory statements. A given electron might, for example, be described as having an upward spin and a downward spin at the same time, or as existing and yet not existing at the same time.[24] Clearly, the implications of such strange notions must be discussed further (see §3). But let us first consider whether or not quantum mechanics in general can be regarded as compatible with Kant’s views on causality.
The arguments Kant devises to defend the second analogy are not intended to prove that everything in nature must have some definite, objective cause, but that our expectation that everything has such a cause is a necessary component of what it means to gain “empirical knowledge” of any phenomenal object or event. The difference between these two is of utmost importance: it is the difference between a non-perspectival and a perspectival interpretive method. The former method would be an attempt to prove that the law of causality holds absolutely, that rational beings have no choice but to view any and every event in terms of the law of causality. Such a claim would make a mockery of Kant’s subsequent attempt to develop a coherent theory of human freedom. The latter (perspectival) method, by contrast, leaves open a space, not only for the “perspectival shift” involved in treating an event in terms of freedom (self-determination) rather than causality (nature-determination), but also for other scientific approaches to nature—approaches that may require less emphasis on the principle of causality.
The first section of this paper explained the relationship between relativity theory and quantum physics in terms of their respective dependence on the upper and lower limits of observation. Both of these, it turns out, are due to the nature of light, which, of course, human beings need in order to observe (see) anything. We can now regard these two limits as establishing empirical boundaries of human knowledge, much as Kant’s principles establish transcendental boundaries. In other words, although Kantian philosophy and contemporary physics have very different spheres of application, there is a clear parallel between them—a parallel that highlights various similarities in the patterns they follow, making them complementary rather than contradictory. For just as Kant argues that space and time are transcendental conditions that set up the boundary within which all sensible intuition must take place, so also relativity theory regards the speed of light as establishing the (upper) empirical boundary for space-time perception. And just as Kant argues that categories such as causality are transcendental conditions that set up the boundary within which all conceptualization must take place, so also quantum physics regards Planck’s constant as establishing the (lower) empirical boundary for our application of causal concepts.
One way to picture the perspectival differences between these ways of talking about the boundaries of our experience is given in Figure 1. Kant’s use of the term “phenomenal world” need not refer to the physical world as such, but to that world as observable. Knowing nothing of the high-energy world of particle physics or low-energy world of astro-physics, he was concerned to account for the ordinary world of observable experiences (especially observable scientific experiences), where energy and matter maintain an equilibrium, balanced at the “crossroads” between the microscopic and macroscopic extremes. This does not mean Kant’s principles could not be described in terms that would embrace the “quantum” and “astral” worlds as well as the “ordinary” world; my point is only that Kant himself did not do so. (Indeed, the present paper will make an attempt to effect just such an extension of Kant’s principles.) When these three “worlds” are regarded as equally legitimate perspectives on one and the same “world”, there is no need to think in terms of reducing the others to a single, “ultimately” valid, point of view.[25] A clear distinction between these perspectives reveals how improper it is to argue from the truth of quantum mechanics to the falsity of Kantian philosophy.
Figure 1: Three
Perspectives on the “World”[26]
Without addressing the issue of whether or not causality holds for the quantum and astral worlds, we can here at least affirm that nothing discovered by either quantum mechanics or relativity physics has any significant influence on the applicability of causality to the ordinary world (i.e., the world as directly visible to the human observer’s eye). For even if quantum events are radically undetermined, so that statistical approximations must forever replace deterministic predictions, the margin of error transferred from the quantum world to the ordinary world is so minuscule as to be undetectable: for all practical purposes, events viewed from the perspective of the ordinary world are still bound by the principle of causality. And as an eighteenth-century philosopher, not a twentieth-century physicist, Kant cannot be blamed for focusing first and foremost on this ordinary world.
As we have seen, the second analogy does not stand alone in Kant’s theoretical system, but is one of three analogies, which, taken together, are themselves but one component in the interdependent set of four basic principles that transcendentally govern all empirical knowledge. Kant’s claim is not simply that we must treat every event as having a cause, but that all observable changes in phenomena (object-events) must be regarded as alterations of a common “substratum” of nature, wholly imperceptible to the science of his day. He called this substratum “substance”. The permanence of substance, the fact that it remains essentially the same in the midst of all phenomenal changes, is defended in the first analogy. (As such, substance is not to be confused with the thing in itself. The latter is an epistemological construct referring to the notion of a transcendent (unknowable) world “in itself”, as viewed from the transcendental perspective, while “substance” refers to the physical world “in itself”, viewed from the empirical perspective, as in Table 1.) The third analogy then argues that we must regard the cause-and-effect changes observed in the world as thoroughly interconnected at a deep level. Taken together, these three principles constitute the conceptual foundation that must be presupposed for any science that is to produce legitimate empirical knowledge.[27]
Understanding the intimate relationship between these three analogies is important because the twentieth-century revolutions in physics do not call into question the first and third analogies, the way they do the second analogy. Once this is recognized, it becomes more plausible to maintain that the lack of a clear role for the principle of causality in the quantum world does not imply that Kant’s arguments in the second analogy are invalid, but only that they were never intended to apply to the world from that perspective. Quantum mechanics examines the empirical substratum of nature in a way that was simply not possible in Kant’s day, revealing it to consist of particles (quarks) that can themselves be manipulated (albeit, only under the extreme conditions present in high energy accelerators). The principle of causality applies mainly to the ordinary world of accidental (“phenomenal”) changes that characterize the objects of Newtonian science.[28] Applying this insight to Heisenberg’s uncertainty principle, the primary source of the common belief that the quantum world is a world of chance, Cohen rightly states that uncertainty
does not necessarily mean a denial of the principle of causality or an assertion of indeterminism in the objective physical world. It may be explained as a consequence of the fact that any measurement which involves observation of nature through light is itself a physical operation, which disturbs the object observed....
... Heisenberg’s principle does not mean a lawless world. It means rather that the laws are of a different sort ... We might venture to suggest that, when the present excitement subsides, it will be found that the permanent results of [Heisenberg’s interpretation of] quantum mechanics confirm rather than overthrow the classical development in physics, just as the Einstein theory is now seen to be a development and completion of the Newtonian mechanics ...[29]
Returning to our central question, can we now say the events that occur at the subatomic level are caused? Most interpretations of quantum mechanics agree that these events are at least to some extent random, happening more on the basis of chance or possibility than necessity. This is taken by many philosophically-minded scientists and scientifically-inclined philosophers to spell the demise of anything like a Kantian view of the phenomenal world. But it does not, so long as we recognize that quantum explanations are limited in their literal application to a specific, well-defined perspective (that of the submicroscopic world). Thus, without compromising a Kantian view of the phenomenal world, we can agree completely when Capra says: “Like our ordinary notions of space and time, causation is an idea which is limited to a certain experience of the world and has to be abandoned when this experience is extended.”[30] For Kant would be the first to admit that, once science tries to “extend” itself beyond the phenomenal world, to a transcendent world (cf. note 18), all the principles break down.[31]
One of the reasons so many physicists and philosophers fail to see the compatibility between quantum mechanics and Kant’s principle of causality is that classical (Newtonian) physicists tended to use the law of causality as the guarantee that, if we know all the variables in a given situation, then we can predict the future with absolute certainty. At first sight, it appears that quantum mechanics contradicts this principle, inasmuch as it maintains the impossibility of ever knowing all the significant facts about a particle at one and the same time. This, however, ought not to be regarded as a positive denial of the principle of causality, but as a denial of the possibility of reductionism. In other words, there is nothing in quantum mechanics that compels us to deny the validity of the above “If ..., then ...” proposition, though many physicists do indeed choose to deny it. What it compels us to deny is the possibility of ever achieving the “if” side of the equation. Quantum mechanics therefore establishes an area of physically necessary ignorance (called the “quantum” world), just as Kant’s Critical philosophy establishes an area of transcendentally necessary ignorance (called the “transcendent” or “noumenal” world). As suggested by Table 1, the two are analogous, though by no means identical.
3. Quantum Causality as an Alternative to Chance
In the search for a plausible explanation of quantum events, some physicists have felt compelled to conjecture that there may be some sort of “quantum causality” after all. This has been conceived in a variety of different ways, including the counter-intuitive hypothesis that future events might somehow “cause” present quantum events to happen. Here I wish to focus on one alternative to such “reverse causation”: namely, the suggestion that the quantum world operates according to a special type of “nonlocal” causality. On this hypothesis, the cause and the effect may exist at great distances from each other, with no observable “direct contact” between them ever taking place. The need for the hypothesis of nonlocal causality first arose in the form of “Bell’s theorem”: in 1964 John Bell demonstrated “that the existence of local hidden variables is inconsistent with the statistical predictions of quantum theory.”[32] This cast serious doubt on Einstein’s conviction that ordinary, local causation exists at the quantum level, but is merely hard to pin down due to some “hidden variables”. Once the presence of such variables was ruled out, the flood-gates were open for alternative explanations as to how quantum events come about.
A commonly-quoted illustration of nonlocal causality is that it would be like “the flutter of a butterfly’s wings in Hong Kong” causing “the weather in New York” to change.[33] On this view, “[t]he behavior of any part is determined by its nonlocal connections to the whole, and since we do not know these connections precisely, we have to replace the narrow classical notion of cause and effect by the wider concept of statistical causality.”[34] This statistical or “quantum” causality[35] has more affinity to Kant’s first and (to a lesser extent) third analogies than to his second analogy: it refers to the deep causality implicit in the notion of a permanent substance underlying everything in the phenomenal world, and insuring that all ordinary causal relations coexist within a common “substratum”.[36] Nevertheless, Kant’s view is once again vindicated in the end, at least in the qualified sense that, because the category of causality resides in our mind,[37] even when physical limitations bar our successful discovery of the cause, the assumption of some type of cause eventually has to be made in order to carry on the task of scientific explanation. The strange character of this type of cause (comparable to that of the “noumenal causality” Kant sometimes seems to defend) results from the fact that it is an attempt to describe the connection between the empirically observable (measured) results of quantum experiments and the unobservable quantum reality that underlies these results.
That the first and third analogies have become the focal point for quantum physics in almost the same way that the second had been the focal point for Newtonian physics is clearly suggested by the following typical claims:
the particle ... cannot be seen as an isolated entity, but has to be understood as an integrated part of the whole.
Quantum theory ... reveals a basic oneness of the universe.... As we penetrate into matter, nature does not show us any isolated ‘basic building blocks’, but rather appears as a complicated web of relations between the various parts of the whole.[38]
Classical physics used a concept of causality that was virtually devoid of mystery. This thing over here in some way contacts that thing over there and in so doing changes it in some way. The causal link is, at least in theory, empirical: if I look hard enough I can see it right in front of my eyes. By contrast, quantum physics, as we have seen, requires the hypothesis of a mysterious, underlying substratum of the physical world (cf. Kant’s first analogy); for it is this and this alone that can serve as the universal ground for the world’s interrelated “wholeness” (cf. Kant’s third analogy), and so also for any attempt to explain how quantum causality-at-a-distance might work. The substratum functions for empirical science in much the same way as the thing in itself functions for transcendental philosophy. In light of this parallel, it is worth suggesting that quantum (nonlocal) causality be regarded as a quasi-transcendent (i.e., observation-defying) link between empirically observable phenomena that appear to be otherwise unrelated.
Returning now to the fanciful illustration of the Hong Kong butterfly whose fluttering wings influence the weather in New York, we can explain such quantum “causality” in a way that reveals how little it has to do with our ordinary notion of phenomenal causality. Nonlocal causation is not based on some hidden chain of unseen causal connections, supposedly stretching all the way from Hong Kong to New York. Rather, the butterfly’s fluttering wings, which do have such a classically causal influence on the immediately surrounding pockets of air (an influence that dissipates long before reaching New York!),[39] are believed to have a quantum-causal influence on the whole. This whole (or “substratum”, as Kant calls it) adjusts itself to the fluttering of the butterfly’s wings; and as a result, any other part of that same whole, whether it be in Kowloon, New York, or Mars, might also need to be readjusted to fit the new situation. As we have seen, this quantum causality need not in any way disconfirm Kant’s three analogies, provided they are taken together as three manifestations of one basic principle —the principle Kant describes as “a necessary connection of perceptions”.[40] It merely changes the way we understand how they are applied to the empirical world. Once this is understood, the suggestion that the new physics is actually more Kantian than the old physics becomes reasonable to maintain. For classical physics was too dependent on an inflated view of the importance of the law of causality. Physicists now know that, as Kant argued, local (“phenomenal”) causality is but one aspect of an interconnected whole that goes far beyond the conventional understanding of ordinary cause and effect.
4. Kantian
Quarks: The Concealed Substratum of Transcendental Philosophy
What, then, are the “Kantian quarks” mentioned in the title of this essay? By this tantalizing phrase I intend to call attention to a triplet of “bare facts” about our world—or more precisely, about our perspectives on that world. As far as human reason can tell, these facts arise out of nowhere, like a quantum leap: their source (if any) is so deeply concealed in our nature that, like the quarks of contemporary quantum mechanics, it can never be “observed”, even by the mind’s eye. Actually, Kant describes a number of aspects of his System in this way,[41] including in one sense, all of the synthetic a priori principles he defends in the Analytic. For in a statement reminiscent of Feynman’s confession of the mystery inherent in quantum mechanics (quoted in §1), Kant says “no concept given a priori ... can, strictly speaking, be defined.”[42] This may seem like a surprising claim, until we recall that for Kant, the term “a priori” applies only to judgments that are rooted in reason rather than in the object, whereas the list of empirical characteristics required by a definition is possible only for observable objects. The “object” being examined in Kant’s entire Critical System is something even more elusive than the atom: reason itself. It should come as no surprise, therefore, to find that, just as scientists have found themselves unable for three decades (and some argue, forever unable) to observe a quark freely wandering around in the world, so also there are three points in his System where Kant makes a special effort to emphasize our inability to fathom the depths of the “object” in question.
Each of the three most fundamental building-blocks of the Critical System (including, here, all three Critiques) is directly related to one of Kant’s three ideas of reason. Functioning like a triplet of “Kantian quarks”, these aspects of reason’s powers can be identified as:
1. The unity of apperception, with the transcendental conditions (namely, space, time, and the categories) that flow from it (cf. the idea of God).
2. The moral law, with the choice that flows from it (cf. the idea of freedom).
3. The productive imagination, with the beauty, sublimity, and natural purposiveness that flow from it (cf. the idea of immortality).
Given Kant’s emphasis on causality in the second analogy, we might expect him to argue that these basic, perspective-defining aspects of our ways of relating to our world are caused by something. Like the modern physicists, however, he refuses to do so. Instead, he depicts them as concealed behind a veil of darkness that human reason is unlikely ever to see beyond—a veil sometimes obscurely described in terms of his infamous theory of “noumenal causality”. Kant postulates the existence of a hidden, qualitatively different sort of reality that in some non-empirical sense must be regarded as “causally” connected to these fundamental “quarks” of transcendental philosophy. Let us now briefly examine each of these in turn, noting in particular the way each corresponds to one of the three Kantian ideas of reason (namely, God, freedom, and immortality).
Transcendental apperception, Kant tells us, is an absolutely necessary, “pure original unchangeable consciousness”, with a “numerical unity”.[43] All the basic, transcendental conditions for the possibility of experience (namely, space, time, and the twelve categories[44]) must be related to this focal point of my self-consciousness in order for me to recognize any experience as “mine”.[45] Yet paradoxically, we cannot see or experience the unity of apperception itself, but only its effects in the empirical world. As such, it is the archetype of all a priori concepts. And, as Kant argues toward the end of the Analytic, all such concepts are completely unintelligible if we try to understand them apart from the way they influence the empirical world:
Although all these principles ... are generated in the mind completely a priori, they would mean nothing, were we not always able to present their meaning in appearances, that is, in empirical objects. We therefore demand that a bare concept be made sensible ... Otherwise the concept would, as we say, be without sense, that is, without meaning.... That this is also the case with all categories and the principles derived from them, appears from the following consideration. We cannot define any one of them in any real fashion ... without at once descending to the conditions of sensibility... For if this condition be removed, all meaning, that is, relation to the object, falls away; and we cannot through any example make comprehensible to ourselves what sort of a thing is to be meant by such a concept.
Thus the analogies and other principles, as well as our sense of “I”, can be known by their effects; but, like quarks, they cannot be known in and of themselves. When we nevertheless allow reason to direct our thinking out beyond the sensible world, in search of the unconditioned object towards which such concepts point us, our particular “I” suggests to us the idea of the highest and most complete form of all “I’s”, that is, the idea of God as a personal being.
Kant emphasizes on a number of occasions that the moral law “is not an empirical fact but the sole fact of pure reason, which by it proclaims itself as originating law”.[46] This “fact”, however, is clearly unlike anything we would normally regard as a fact, inasmuch as we can neither empirically observe nor logically prove its existence. Yet, Kant assures us, it is “not empty”, but “provides reality to a supersensible object of the category of causality, i.e., to freedom.”[47] Like the physicists with their quarks, we are impelled to take freedom and the moral law as givens when we look at the evidence provided by our moral life. The moral law is, for all practical purposes, identical to what Kant elsewhere calls the “good will”. As Kant says in the famous opening sentence of the First Section of his Foundations of the Metaphysics of Morals: “Nothing in the world—indeed nothing even beyond the world—can possibly be conceived which could be called good without qualification except a good will.”[48] And freedom is the mysterious, unconditioned root of the moral law. Moral beings are therefore just as bound to formulate the idea of their own freedom as self-conscious (apperceptive) beings are to formulate the idea of God.
Just as the first two Kantian “quarks” correspond mainly to the first and second Critiques, respectively, the third corresponds mainly to the third Critique, where Kant examines the transcendental underpinnings of our experiences of beauty, sublimity, and natural purposiveness. The power of the human mind that makes such experiences possible, according to Kant, is imagination. In the first Critique Kant distinguishes between reproductive imagination (i.e., memory) and the properly transcendental function of productive imagination.[49] The latter, he claims, is the power that lies behind the “schematism” of the categories, whereby these pure concepts are made amenable to intuitions, without which the principles (and so also, empirical knowledge itself) could never arise. Although he has no trouble recognizing the effects of the imagination, Kant confesses that this operation “is an art concealed in the depths of the human soul, whose real modes of activity nature is hardly likely ever to allow us to discover, and to have open to our gaze.”[50] When the imagination comes into its own arena in the third Critique, the situation is hardly improved. For, although Kant offers us no shortage of insights into the nature of beauty, sublimity, and natural purposiveness, he frequently appeals to paradoxical (quark-like) notions, such as “subjective universality” and “purposiveness without a purpose”.[51] Without straying into a detailed discussion of these obscure corners of the Kantian System, it will suffice merely to point out that, when we allow reason to follow this power of productive imagination—this art concealed in the human soul—to its unconditioned source, the idea of our soul’s immortality arises in our minds.
Recognizing these Kantian “quarks” enables us to see even more clearly how Kant’s overall method of thinking is actually closer to the quantum mechanical model than to the classical, Newtonian model, so that this twentieth-century revolution in physics, far from proving Kant’s System to be mistaken, actually confirms it in ways Kant himself could never have foreseen. In the world of classical science, it would have been regarded as a gross blunder to postulate unknown and unknowable realities that are somehow fundamentally altered by the very act of our observing them. But now, with the advent of quantum mechanics, such a viewpoint can almost be taken for granted as legitimate. As we have seen, this simply is the Kantian perspective on science, when the latter is understood in its full systematic context. Indeed, it appears to be a direct outworking of the Transcendental Perspective as such to view the human mind as, so to speak, “quark-like”.[52] Or, passing from what is unknowable because of being infinitely close to us, to what is unknowable because of being infinitely far away, we could also compare Kant’s conception of reason’s ideas to a kind of spiritual “black hole”: an unobservable point, detectable only because of how it affects other things, drawing everything to itself, yet excluding everything but itself from its inner core.
In conclusion, let us now draw together the key perspectival distinctions suggested throughout this essay in the process of relating Kant’s theoretical system to the scientific revolution effected by quantum mechanics. In so doing, it may be helpful to recall that the nature and function of light has cropped up on numerous occasions in different ways. This is more than just an interesting coincidence. For light, more than any other natural phenomenon, is what makes perspectives possible. A perspective is a way of seeing something; as insight into the mind’s mode of operation, a perspective is directly analogous to the sight that is possible only when we are in the presence of light. Light manifests itself on three levels, corresponding directly to the three perspectives, or “worlds”, pointed out in Figure 1. We saw in §1 that the upper and lower limits of observation are both determined by light. Though the speed of light is absolute, and thus regular and predictable, it functions (as Einstein demonstrated) to make everything else in space-time relative. Absolute light is for physics (especially astro-physics) what the transcendental perspective is for Kant’s System. Planck’s constant, by contrast, determines the smallest possible quantity of energy, beyond which we can only think hypothetically. The submicroscopic world it demarcates is, as quantum physics has taught us, highly irregular. Yet neither of these “strange” perspectives on light denies the reality of the ordinary, “empirical” light that makes our phenomenal world visible. As Newton rightly demonstrated, everything that appears in this light comes under causal laws—though Einstein has taught us to view these laws as themselves relative to a higher absolute. Table 2 shows how these three perspectives on light correspond directly to the three “worlds” shown in Figure 1, to Kant’s three analogies, [53] as discussed in §2, and to the triplet of “Kantian quarks” (with their corresponding “ideas”) outlined earlier in this section. Seeing these connections should help us to appreciate more fully the significance of the insight conveyed by the writer of Genesis, that the first words God spoke into the darkness of the primal chaos must have been: “Let there be light ...”.[54]
Table 2: Perspectival Distinctions in Kant’s
Foundation for Modern Science
FOOTNOTES