In my previous post, ‘Kant and self-knowledge’, I pointed out that Kant’s view of human mind is strikingly similar to the view of human spiritual nature that neurophysiology opens for us.
In the light of neurophysiology the world we perceive is formed in us on the basis of the information processed by our brain, which is differently structured in the space of our brain than the world, which we see around us, is structured in space. There are many forms of movement and change within the nerve system: electric action potentials are propagated along the nerve fibres; the sodium pumps swap sodium ions on the inside of neurons with potassium ions on the outside of them … But none of these movements and changes model movements and changes we can observe in the world around us. The information concerning the outside world, processed by the brain, must be transformed into the world of our consciousness, which is in its totality in us.
In the Critique of pure reason Kant asks: ‘Now, how can an external intuition (Wie kann nun eine äussere Anschauung) anterior to objects themselves, and in which our conception of objects can be determined a priori, exist in human mind (dem Gemüte beiwohnen, die vor den Objekten selbst vorhergeht, und in welcher der Begriff der letzteren a priori bestimmt werden kann?)?’ He answers: ‘Obviously not otherwise (Offenbar nicht anders,) than in so far as it has its seat in the subject only, as the formal capacity of the subject’s being affected by objects, and thereby of obtaining immediate representation, that is intuition (als so fern sie bloss im Subjekte, als die formale Beschaffenheit desselben, von Objekten affiziert zu werden, und dadurch unmittelbare Vorstellung derselben d. i. Anschauung zu bekommen); consequently, only as the form of the external sense (also nur als Form des äusseren Sinnes überhaupt.).’ (B 41, tr. Meiklejohn)
But there is a profound paradox concerning this similarity, for from Kant’s point of view space has no objective reality, whereas neurophysiology could develop only because scientists regarded the outside world of our sensory perception as a stepping stone towards examining things in the outside world in their relation to one another, observing what effects they have on each other, what they do to each other – in space and time that have objective reality.
Kant says that ‘space does not represent any property of objects as things in themselves, nor does it represent them in their relations to each other (Der Raum stellt gar keine Eigenschaft irgend einiger Dinge an sich, oder sie in ihrem Verhältnis auf einander vor,); in other words, space does not represent to us any determination of objects such as attaches to the objects themselves (d. i. keine Bestimmung derselben, die an Gegenständen selbst haftete,), and would remain (und welche bliebe,), even though all subjective conditions of the intuition were abstracted (wenn man auch von allen subjektiven Bedingungen der Anschaung abstrahierte.).’ (B 42) His ‘expositions, consequently, teach the reality (Unsere Erörterungen lehren demnach die Realität) (i.e. the objective validity (d.i. die objective Gültigkeit)) of space in regard of all (des Raumes in Ansehung alles dessen,) which can be presented to us externally as object (was äusserlich als Gegenstand uns vorkommen kann,), and at the same time also (aber zugleich) the ideality of space (die Idealität des Raumes) in regard to objects (in Ansehung der Dinge,) when they are considered by means of reason as things in themselves (wenn sie durch die Vernunft an sich selbst erwogen werden,), that is, without reference to the constitution of our sensibility (d. i. ohne Rücksicht auf die Beschaffenheiten unserer Sinnlichkeit zu nehmen.).’ And so he maintains that ‘space is nothing (dass er nichts sei,), so soon as we withdraw the condition upon which the possibility of all experience depends (sobald wir die Bedingung der Möglichkeit aller Erfahrung weglassen,) and look upon space as something that belongs to things in themselves (und ihn als etwas, was den Dingen an sich selbst zum Grunde liegt, annehmen).’ (B44)
In contrast, physics is all about the world outside us. It tells us that our eyes are affected neither by light, nor the objects we see around us or by their images, but by the electromagnetic waves scattered by those objects. Neurophysiology tells us that these electromagnetic waves affect photoreceptors on the retina of our eyes, which in their turn trigger a chain of chemical and electrical effects propagated by optic nerves. These effects are processed on the way to the brain and in the visual cortex of the brain. There is no light in the outside world which is the domain of physics, and no light in the brain itself, which is the domain of neurophysiology. On the basis of the physiological processing of the optic information in the brain something in us generates light in us and the world which we see in that light as being outside us. In ‘Self-knowledge as an imperative’ on my website I have adopted for this ‘something in us’ the term human spiritual nature, HSN.
The world outside us described by physics is linked to the ‘world outside us’ of our consciousness by our nerve system, so that the latter points to the former in all its objective reality. For Kant, space and time have only subjective reality; they are nothing without their reference to our sensory nature. In spite of this profound difference, the Kantian subjectivity of space and time remains relevant for our understanding of human spiritual nature.
Kant says: ‘Time is the formal condition a priori (Die Zeit ist die formale Bedingung a priori) of all phenomena whatsoever (aller Erscheinungen überhaupt). Space (Der Raum,), as the pure form of external intuition (als die reine Form aller äusseren Anschauung), is limited as a condition a priori to external phenomena alone (ist als Bedingung a priori bloss auf äussere Erscheinungen eingeschränkt.). On the other hand (Dagegen,), because all representations (weil alle Vorstellungen,), whether they have or have not external things for their objects (sie mögen nun äussere Dinge zum Gegenstande haben, oder nicht,), still in themselves (doch an sich selbst,), as determinations of the mind (als Bestimmungen des Gemüts,), belong to our internal state (zum inneren Zustande gehören,); and because this internal state is subject to the formal condition of the internal intuition, that is, to time (dieser innere Zustand aber, unter der formalen Bedingung der inneren Anschauung, mithin der Zeit gehört,) – time is a condition a priori of all phenomena whatsoever (so ist die Zeit eine Bedingung a priori von aller Erscheinung überhaupt,) – the immediate condition of all internal, and thereby the mediate condition of all external phenomena (und zwar die unmittelbare Bedingung der inneren (unserer Seelen) und eben dadurch mittelbar auch der äusseren Erscheinungen). If I can say a priori (Wenn ich a priori sagen kann:), “All outward phenomena are in space (alle äusseren Erscheinungen sind im Raume, und nach den Verhältnissen des Raumes a priori bestimmt,),” I can also, from the principal of the internal sense, affirm universally (so kann ich aus dem Prinzip des inneren Sinnes ganz allgemein sagen:), “All phenomena whatsoever (alle Erscheinungen überhaupt), that is, all objects of the senses (d. i. alle Gegenstände der Sinne), are in time (sind in der Zeit,) and stand necessarily in relations of time (und stehen notwendigerweise in Vehältnissen der Zeit.).”’ (B50-51, tr. Meiklejohn, with one exception; I wrote: All phenomena whatsoever (alle Erscheinungen überhaupt) for Meiklejohn’s All phenomena in general.)
If we compare and contrast the immediate content of our consciousness, that is the world as we see it in front of us, with the information concerning the world in front of us processed in our brain – the more we study neurophysiology, the more pronounced the contrast becomes – the importance of the Kantian notion of space and time as a priori conditions of our subjectivity becomes obvious.