The paradox of human subjectivity

Our two selves: containing the world and being contained in it

In an essay written during the last year of his life, Erwin Schrödinger¹ expressed astonishment at the fact that in spite of “the absolute hermetic separation of my sphere of consciousness” from everyone else’s, there is “a far-reaching structural similarity between certain parts of our experiences, the parts which we call external; it can be expressed in the brief statement that we all live in the same world.”

If I see you looking at a flower, I infer that you see a flower, but I am not aware of what the flower looks like to you. Your “sphere of consciousness” is hermetically sealed off from mine, as is mine from yours. Yet we often agree that we are seeing or otherwise experiencing the same thing. How so? The obvious explanation is that, as far as the two of us are concerned, there are three worlds: a self-existent real world plus the world you perceive plus the world I perceive. There is a real flower that causes both of us to perceive a flower. This, Schrödinger insisted, “is not to give an explanation at all; it is simply to state the matter in different words. In fact, it means laying a completely useless burden on the understanding”—the burden of understanding the relation between the experienced world and an empirically inaccessible world.

Back in 1955, Harold Schilling² contrasted popular belief about science, which he described as “a sort of intellectual machine, which … inevitably grinds out ultimate truth in sequential steps,” with “science as lived by its practitioners,” and concluded that

we have come to realize, as perhaps no scientists before us ever have, that the human observer or explorer and his experience are integral and determinative parts of whatever world he is studying.

The concept of (scientific) truth as a (progressively attainable) correspondence between the constructs of science and the world in itself has a long history. The oldest known correspondence theory of truth, which endured for approximately 2,000 years, is the one that ancient and medieval philosophers have attributed to Aristotle. It holds that the relation between the phantasm and the external object, by virtue of which the phantasm represents the external object to the mind, is literally a relation of similarity.

To 17th-Century thinkers like Descartes and Locke, it still seemed to pose no difficulty to conceive of perceived sizes and shapes as similar to real sizes and shapes. That a perceived color should be similar to color in the external world was a more questionable proposition (as it had been for Aristotle). Locke and Descartes therefore distinguished between “primary qualities,” which were independent of the perceiving subject, and “secondary qualities,” which bore no similarities to sensations but had the power to produce sensations in the perceiving subject. Eventually, though, thinking of perceived sizes and shapes as similar to real sizes and shapes proved to be no less questionable than the proposition that color sensations are similar to colors in the external world. (Berkeley made it clear that to ask whether a table is the same size and shape as my mental image of it was to ask an absurd question.)

In his Critique of Pure Reason, which ranks as one of the most influential philosophical works of all time, Immanuel Kant³ starts out by saying that all qualities are secondary in Locke’s sense. Nothing of what we say about an object describes the object as it is in itself, independently of how it affects us. Nor does Kant stop at saying that if I see a desk, there is a thing-in-itself that has the power to appear as a desk, and if I see a chair in front of the desk, there is another thing-in-itself that has the power to appear as a chair. For Kant, there is only one thing-in-itself, an empirically inaccessible something that has the power to affect us in such a way that we have the sensations that we do, and that we are in a position to “work up the raw material of sensible impressions into a cognition of objects.”

“Look,” Kant said in effect, “natural science exists. We have Newton’s laws of motion, the law of gravity, and various other laws. So let us find out what must be the case on our part so that we can have such a thing as natural science.” He did not presume to inquire into the metaphysical underpinnings of this fact. He resolved to determine its cognitive underpinnings. The position taken by him was that the objective world is constructed by the human mind from sensory material that is passively received and concepts that owe their meanings to the logical structure of rational thought and the spatiotemporal structure of human sensory experience.

The most important of these concepts are substance and causality. The link between substance and logic was first forged by Aristotle. To Aristotle, a property was whatever could be the predicate of a logical subject, while a substance was something that could not be predicated of anything else. Substances, therefore, enjoyed independent existence, while properties owed their existence to being attributes of substances. Locke subsequently distinguished between two conceptions of substance: (i) a “notion of pure substance in general” and (ii) “ideas of particular sorts of substance.” The first was to him “nothing but the supposed, but unknown, support of those qualities we find existing, which we imagine cannot subsist sine re substante, without something to support them.” In other words, it was something that the qualities we find existing do not need—“any more than the earth needs an elephant to rest upon,” as Bertrand Russell later put it. Substances in sense (ii) are sometimes referred to a Lockean substances. They are “such combinations of simple ideas as are, by experience and observation of men’s senses, taken notice of to exist together.” They bring into play another function of the logical subject: substance can combine different “simple ideas” in the same way that a logical (or grammatical) subject can combine different predicates.

In Kant’s theory of science, substance fulfills both functions: like a Lockean substance it serves to bundle sensible impressions in the manner in which a logical subject bundles predicates, and like an Aristotelean substance it makes it possible for me to think of my sensible impressions as connected not in or by me but in or by an external object. This allows me to ignore the fact that the external object owes its existence largely to me, the perceiving and thinking subject.

The concept of causality likewise performs two functions. It allows me to think of impressions received at different times as connected in accordance with the logical relation between an antecedent and a consequent (if … then …), and it makes it possible for me to think of my successive perceptions as connected not in me, by my experiencing them, but objectively, as causes and effects in an external world. (Kant believed that another concept was needed to objectivize the temporal relation of simultaneity. In a relativistic world, in which simultaneity cannot be objectivized, no such concept is needed.)

The possibility of thinking of my perceptions as a self-existent system of external objects also requires that the connections be lawful. If sense impressions are to be perceptions of a particular kind of object (say, an elephant) they must be connected in an orderly fashion, according to a concept denoting a lawful concurrence of perceptions. And if sense impressions are to be perceptions of causally connected occurrences, like (say) lightning and thunder, they must fall under a causal law, according to which one perception necessitates the subsequent occurrence of another. It is this lawfulness, which (unlike the concepts through which it comes to be expressed) is not rooted in the structure of human cognition, that warrants the objectivity of those parts of our experiences which we call external.

Schrödinger⁴ has put forward “two general principles that form the basis of the scientific method”—not in order to prescribe what they ought to be but in order to characterize science “as it has developed and has become and at present is.” The first—the “principle of the understandability of nature”—seems self-evident: you cannot study nature without proceeding on the assumption that nature can be understood. As self-evident as it seems, it raises the intriguing question as to why nature is as comprehensible as it is—not more but also not less so. Einstein⁵ has frequently been misquoted as saying that “the most incomprehensible thing about the universe is that it is comprehensible.” What he actually wrote is this:

The very fact that the totality of our sense experiences is such that by means of thinking (operations with concepts, and the creation and use of definite functional relations between them, and the coordination of sense experiences to these concepts) it can be put in order, this fact is one which leaves us in awe, but which we shall never understand. One may say “the eternal mystery of the world is its comprehensibility.” It is one of the great realisations of Immanuel Kant that the setting up of a real external world would be senseless without this comprehensibility.

Einstein then goes into greater detail regarding his meaning of “comprehensibility”:

It implies: the production of some sort of order among sense impressions, this order being produced by the creation of general concepts, relations between these concepts, and by relations between the concepts and sense experience, these relations being determined in any possible manner. It is in this sense that the world of our sense experiences is comprehensible. The fact that it is comprehensible is a miracle.

The reference to Kant leads directly to the second general principle put forward by Schrödinger. He calls it “the principle of objectivation.” In Schrödinger’s own words, objectivation

amounts to a certain simplification which we adopt in order to master the infinitely intricate problem of nature. Without being aware of it and without being rigorously systematic about it, we exclude the Subject of Cognizance from the domain of nature that we endeavour to understand. We step with our own person back into the part of an onlooker who does not belong to the world, which by this very procedure becomes an objective world.

Two circumstances prevent us from recognizing this state of affairs:

First, my own body (to which my mental activity is so very directly and intimately linked) forms part of the object (the real world around me) that I construct out of my sensations, perceptions and memories. Secondly, the bodies of other people form part of this objective world. Now I have very good reasons for believing that these other bodies are also linked up with, or are, as it were, the seats of spheres of consciousness. I can have no reasonable doubt about the existence or some kind of actualness of these foreign spheres of consciousness, yet I have absolutely no direct subjective access to any of them. Hence I am inclined to take them as something objective, as forming part of the real world around me. Moreover, since there is no distinction between myself and others, but on the contrary full symmetry for all intents and purposes, I conclude that I myself also form part of this real material world around me. I so to speak put my own sentient self (which had constructed this world as a mental product) back into it—with the pandemonium of disastrous logical consequences that flow from the aforesaid chain of faulty conclusions.

Schrödinger⁶ mentions two of these consequences. The first is that sensory qualities (nowadays usually called “qualia”) “are lacking in a world model from which we have removed our own mental person.” The second is “our fruitless quest for the place where mind acts on matter or vice-versa”:

The material world has only been constructed at the price of taking the self, that is, mind, out of it, removing it; mind is not part of it; obviously, therefore, it can neither act on it nor be acted on by any of its parts.

If, oblivious to the fact that “a moderately satisfying picture of the world has only been reached at the high price of taking ourselves out of the picture, stepping back into the role of a non-concerned observer,” we reify this world model, we are forced to give our sensory qualities “a living space,” to “invent a new realm for them, the mind, saying that this is where they are, and forgetting the earlier part of the story”.⁷ The result is the mind-body problem, which is as notorious as it is spurious.

The human condition can be described in the form of a dilemma, whose two horns are (i) the existence of consciousness in what appears to be a material world and (ii) the existence in consciousness of what appears to be a material world. Edmund Husserl⁸ once referred to it as “the paradox of human subjectivity: being a subject for the world and at the same time being an object in the world.”

Drawing by Jolyon Troscianko (jolyon.co.uk). Used with permission.

Taking hold of the dilemma’s objective horn (and focusing on perception), we can gain an understanding of causal chains leading from external objects to firing patterns in brains, but then we find ourselves stymied by the notorious explanatory gap between neural processes and conscious experience. Here is how this issue has been addressed by Hilary Putnam⁹:

How does the familiar explanation of what happens when I “see something red” go? The light strikes the object (say, a sweater), and is reflected to my eye. There is an image on the retina…. There are resultant nerve impulses…. There are events in the brain, some of which we understand thanks to the work of Hubel and Wiesel, David Marr, and others. And then—this is the mysterious part—there is somehow a “sense datum” or a “raw feel.” This is an explanation? An “explanation” that involves connections of a kind we do not understand at all … and concerning which we have not even the sketch of a theory is an explanation through something more obscure than the phenomenon to be explained.

Taking hold of the dilemma’s subjective horn, we can gain an understanding of the general structure of empirical knowledge, its dependence on the logical structure of rational thought and the spatiotemporal structure of human perceptual experience, but then we find ourselves stymied by the same explanatory gap approached from the other side: the brains studied by neuroscience are themselves objects of perceptual experience, and objects of perceptual experience cannot be uncritically identified with whatever it is that causes perceptual experience.

To illustrate this point, consider the following situation. Alice, a neuroscientist, observes a specific complex of neural processes taking place in Bob’s visual cortex each time she sees a green apple located in Bob’s visual field. (The visual field is the entire area that can be seen when the eyes are directed forward. The visual cortex is the part of the cerebral cortex that processes information received from the eyes. The cerebral cortex is the outer, most recently evolved part of the mammalian brain.) Something in Alice’s experience of Bob’s brain corresponds to something in her experience of what Bob is looking at. There are correlations between what, in Alice’s experience, goes on in Bob’s visual cortex and what, again in Alice’s experience, is situated in Bob’s visual field. If Bob tells her that he, too, sees a green apple, it confirms the existence of correlations between what Bob experiences and what Alice experiences. Such correlations underlie our belief in a shared external world.

Does this warrant the inference that there is an unexperienced real apple, and that this causes the applish experiences Bob and Alice have in common? Most decidedly not. When we say, “this is a green apple,” we state the correspondence of a perception to a schema—an empirical rule for associating a particular concept with a particular experience. (The seminal idea that the perceptual and conceptual aspects of experience are linked by schemata, is due to Kant. Today people prefer to speak of “perceptual invariants.”) While our judgment that this is a green apple goes beyond what is immediately experienced, it does not reach beyond what is given in experience. It merely involves the claim that this thing is of much the same color, shape, and consistency as the things we previously judged to be green apples, or the claim that this particular experience is of the same kind as experiences we previously referred to as “green apples.” Representations, as Ernst von Glasersfeld¹⁰ put it, “are (and cannot be anything but) re-presentations of experiential material that was present at some other time.”

As far as I know, this point was first made by Friedrich Lange in his monumental and hugely influential work on the history of materialism, which was published in 1866. Lange¹¹ draws attention to the fact that even our body, our sensory organs, our nerves, and our very brain all figure as elements in the world of experience, and are consequently nothing but unfaithful images and signs of something unknown:

The eye, with which we believe we see, is itself only a product of our ideas; and when we find that our visual images are produced by the structure of the eye, we must never forget that the eye too with its arrangements, the optic nerve with the brain and all the structures which we may yet discover there as causes of thought, are only ideas, which indeed form a self-coherent world, yet a world which points to something beyond itself.

So this is where we are. Something in the (more or less) self-coherent world we have constructed from our experiences (notably, our sensory organs and brains) points to something beyond this world, something that lies at the origin of our experiences, yet neither do we have the slightest idea of what this is, nor do we know how these cognitive structure fit into the picture. And if we reify this (more or less) self-coherent world with its bodies and cognitive structures, we do not have the slightest idea of how we come to have the experiences that we have.

Most philosophers have found the paradox of human subjectivity intolerable; hence the common attempt to eliminate one or the other of our two selves—the transcendental self for which the world exists, or the empirical self which exists in the world, as an aspect or attribute of a physical body. The common reaction in our own day is to eliminate subjectivity altogether by some kind of physicalist reduction. This inevitably leads to the spurious “hard problem of consciousness” and on to looking-glassing such words as “self” and “consciousness.” (The phrase “looking-glassing a term” was coined by Galen Strawson¹² to mean using the term “in such a way that whatever one means by it, it excludes what the term actually means.”)

1. E. Schrödinger, What is real? In: My View of the World (Cambridge University Press, 1964).

2. H.K. Schilling, A Human Enterprise: Science as lived by its practitioners bears but little resemblance to science as described in print, Science 127, 1324–1327 (1958).

3. I. Kant, Critique of Pure Reason (Cambridge University Press, 1998).

4. E. Schrödinger, The Principle of Objectivation. In: What Is Life? With: Mind and Matter & Autobiographical Sketches (Cambridge University Press, 1992).

5. A. Einstein, Physics and reality, Journal of the Franklin Institute 221, 349–382 (1936).

6. E. Schrödinger, op. cit. (The Principle of Objectivation).

7. E. Schrödinger, The Interpretation of Quantum Mechanics, edited and with introduction by M. Bitbol, p. 145 (Ox Bow Press, 1995).

8. E. Husserl, The Crisis of European Sciences and Transcendental Phenomenology (Northwestern University Press, 1970).

9. H. Putnam, The Many Faces of Realism (Open Court, 1987).

10. E. von Glasersfeld, Facts and the Self from a Constructivist Point of View, Poetics 18, 435–448 (1989).

11. F.A. Lange, The History of Materialism and Criticism of its Present Importance (Kegan Paul, 1925/1865).

12. G. Strawson, Real Naturalism. In: Things That Bother Me: Death, Freedom, the Self, Etc. (New York Review Books, 2018).