- The Boundary: Scientific vs. Philosophical or Spiritual Inquiry
It might be said that religion begins where science ends. And it may be turning out that quantum theory has indeed taken us to that point. But first of all, let’s take a quick look at what science is. Science is fundamentally about the observable world — it’s about what we can collectively observe and measure, and about which we have some basis for supposing that we’re all looking at the same thing and seeing it in essentially the same way. Thus, it is fundamentally based on a clear subject-object distinction, where in general many inquiring subjects (theorists and experimenters) are analyzing and measuring the same object. However, as we move to smaller and smaller scales of observation, we find that this is not so easy or straightforward to do; and this is because we run into a fundamental problem with our usual assumption that we can separate our modes of detection (which is required for any observation) from what it is we are trying to observe.
At the quantum level, ‘objects’ behave in what is called a ‘contextual’ manner. That is, they exhibit different kinds of behavior based on how we choose to measure them. This is the well-known ‘wave-particle duality’, in which a quantum object such as an electron will exhibit wavelike interference in an experiment designed to measure its wavelike (extended, non-localized) properties, but it will exhibit particle-like behavior (such a spot on a detection screen) in an experiment designed to localize it. This tells us that the same underlying reality (electron as a quantum system) can give rise to very different phenomena, and that we can never ‘pin down’ that underlying reality to one unambiguous phenomenon. This is not just a pragmatic difficulty: the theoretical description of the underlying reality — the so-called ‘wave function’ that is the solution to the Schrodinger equation of quantum theory — has a mathematical property that literally says that the electron is neither a wave nor a particle, but potentially both.
“Potentially” is the operative word here. Werner Heisenberg, a key pioneer of quantum theory, had this to say about quantum objects described by this ‘wave function’ or ‘probability wave’: “The probability wave …was a quantitative version of the old concept of “potentia” in Aristotelian philosophy. It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality. 
He also put it this way:
Atoms and the elementary particles themselves… form a world of potentialities or possibilities rather than things of the facts.”
By “things of the facts,” Heisenberg meant the empirically observable world–the world of appearance. Thus, he understood that quantum theory was pointing to something beyond the world of appearance, and in order to do that, he was allowing for the possibility that reality consists of more than the world of appearance. In doing so, he was of course venturing beyond empirical science and into philosophical territory. And of course, beyond the purely philosophical lies the domain of spiritual inquiry.
- Appearance vs Reality
In the West, the ancient Greek philosopher Plato already had useful insights into this distinction between the observable and the unobservable levels of reality. He said that reality consisted of two different levels: (i) the level of appearance and (ii) the level of fundamental reality–the underlying, hidden reality, which he conceived of as a realm of “Perfect Forms.” His famous allegory of the The Cave was designed to illustrate this distinction. In this story, prisoners are chained deep in a cave, facing a wall on which shadows are cast. The wall is all that they can see, and the phenomena on the wall seem to them to be their entire reality. However, unbeknownst to the prisoners, just outside the mouth of the cave there is a bright light, and people are coming and going between the light and the prisoners, carrying various objects whose shadows are cast on the wall. For Plato, the exterior of the cave, the objects being carried by the people, and the bright light comprise the hidden world of perfect forms (the fundamental reality), while the wall upon which the prisoners gaze is our ordinary world of experience.
We encounter the same contrast between a fundamental, unmanifest reality and an emanated, manifest world of appearance in the Vedic concept of ‘Maya’. While this term has been used in various ways throughout the Easten world, one of its chief uses is to denote the world of appearance as distinct from–and even as obscuring–the underlying, hidden reality. As mythologist Wendy Doniger observes, “to say that the universe is an illusion (māyā) is not to say that it is unreal; it is to say, instead, that it is not what it seems to be, that it is something constantly being made. Māyā not only deceives people about the things they think they know; more basically, it limits their knowledge.” This is very similar to Plato’s allegorical warning that we are deceived when we take the phenomenal ‘shadow play’ as the final story about reality.
The 18th century German philosopher Immanuel Kant also distinguished two fundamental aspects of objects: (1) the object of appearance and (2) the ‘thing-in-itself’, apart from its appearances, which he stated was unknowable. Kant used the Greek term ‘noumenon’ for this second unseen aspect of an object, which translates roughly as ‘object of the mind’. Kant also proposed that there are ‘categories of experience’ that make knowledge of the world of appearance possible. But, unlike Plato and the Eastern philosophers and theologians, Kant assumed that “knowledge” was only about the world of appearance–he held that the world of noumena was unknowable. Kant’s ‘categories of experience’ consisted of concepts like space, time, and causality. But we should take note that Kant proclaimed that Euclidean space was an ‘a priori’ category of understanding, meaning a necessary concept behind any knowable phenomenon—an assertion which has since been decisively falsified by relativity’s non-Euclidean accounts of spacetime. This error illustrates the danger of making categorical assumptions about what principles are required (or conversely, are to be excluded) in order for gaining knowledge about reality, whether at the level of appearance or otherwise.
Twentieth century philosopher Bertrand Russell also had some interesting things to say about the distinction between appearance and reality. In the first chapter of his book, The Problems of Philosophy, he takes us on an exploration of an ordinary table, which leads to an unexpected puzzle. He notes that the table appears differently depending on the conditions under which we observe it, and even to different people who may have different visual capabilities. Finally, he says:
“the real shape[of the table] is not what we see; it is something inferred from what we see. And what we see is constantly changing shape as we move about the room so that here again the senses seem not to give us the truth about the table itself, but only about the appearance of the table. Similar difficulties arise when we consider the sense of touch. It is true that the table always gives us a sensation of hardness, and we feel that it resists pressure. But the sensation we obtain depends upon how hard we press the table, and also upon what part of the body we press with. Thus the various sensations due to various pressures or various parts of the body cannot be supposed to reveal directly any definite property of the table, but at most to be signs of some property which perhaps causes all the sensations, which is not actually apparent in any of them. … it becomes evident that the real table, if there is one, is not the same as what we immediately experience by site or touch or hearing. The real table, if there is one, is not immediately known to us at all but must be an inference from what is immediately known. Thus, two very difficult questions at once arise: (i) is there a real table at all? (ii) If so, what sort of object can it be?”
Recall that this was the same contrast that Plato highlighted in his allegory of The Cave. He noted that the world of appearance is quite different from the real world or the underlying reality–just as, according to the concept of maya, reality is not what it appears to be. Bertrand Russell laid out quite effectively how hard it is to actually know anything about the underlying reality: something as trivial and obvious as a table has been analyzed to the point where it seems to have almost disappeared; we are having trouble getting at what the real table is, or even whether there really is one at all.
This is a notorious problem in philosophy, and there are various approaches to solving this problem and perhaps getting around it. There are a great many modern philosophers who feel that they may have resolved this problem by revising the whole way that we approach the question of how we know about the “real table” that we think is out there. But the bottom line is that we have to take into account that what is directly accessible to us, especially as scientists, is the world of appearance. Western empirical science is first and foremost about the world of appearance by definition, because it’s about what we can observe. In that respect, it must be limited to the ‘Cave.’ It is very hard to justify, within empirical science, saying anything at all about the reality that underlies the appearances.
On the other hand, it is Western science that came up with quantum theory, which ironically seems to point to a domain outside the Cave, in that the mathematical properties of the theory dictate that what it describes is not something that can be contained within the Cave! This is the fundamental source of the controversy over the interpretation of quantum theory–it is why many practitioners of quantum theory wish to deny that the theory actually describes anything real. To do so would be to admit that ‘reality’ must go beyond the Cave-world of appearance.
Thus, while science as a system of knowledge is very rigorous and capable of providing us with well corroborated theories, when we want to talk about those theories as providing facts, we need to take into account that what we take as facts have to be limited to the world of appearance. When we consider using science to talk about an underlying reality, we enter into some very difficult and puzzling issues –and much attendant controversy–because we are faced with a choice: either (i) to acknowledge that science cannot answer all our questions about reality, or (ii) if we want to insist that it does, to make a philosophical (as opposed to scientific!) choice that all there is to reality is the world of appearance. The reason that (ii) cannot be a purely scientific choice is that empirical science, being limited to the world of appearance, cannot itself determine whether or not there is an aspect of reality beyond the world of appearance! If we opt for (i), as scientists and as philosophers of science, we celebrate the power and utility of science, but we acknowledge its limitations as well. In the next installment, we’ll look more closely at the pitfalls of opting for (ii), especially without being aware that doing so goes well beyond science.
 Heisenberg, W. (2007). Physics and Philosophy. New York: HarperCollins.
 Wendy Doniger O’Flaherty (1986). Dreams, Illusion, and Other Realities. University of Chicago Press, p. 119.
 Russell, B. (1912). The Problems of Philosophy. Public Domain.
 As quoted in Jammer, M. (1993). Concepts of Space: the History of Theories of Space in Physics. New York: Dover Books. p. 189.