I haven’t read much Kant, but I’m aware of his terms “phenomena/phenomenon” and “noumena/noumenon” and the fact that he thinks the the noumenon, the thing in itself, is impossible to reach or to know. The phenomenon refers to the thing (meaning any given thing, whatever you’re perceiving) as it appears to us. The noumenon refers to the thing itself, or the thing in itself, external to our perception of it.
We know the noumenon is something distinct from the phenomenon because it’s possible to be wrong about what you perceive, to perceive something incorrectly. Aspects of the way we model reality such as object permanence, the idea that an object stays where it last was or continues to exist and have a position even when we’re not looking at it and is observed to still be in the same place when we look again (unless it moved), also suggest the independence things in themselves.
I’m sympathetic to the view that the thing in itself is unreachable. While we know how something appears to us perceptibly, we can’t necessarily know the underlying relationship between the perception and what’s being perceived. And whatever we do know through observation or inference from observation about what comes between our perception and the thing itself, we wouldn’t know what comes between that thing and the thing in itself, and if we did know that from inference from observations, we wouldn’t know what comes between that thing and the thing in itself, ad infinitum. It’s the ad infinitum part that makes it impossible to know the full objective relationship between the perception and the thing in itself, and hence impossible to reach the thing in itself.
We also know empirically that the relationship between our mental impression of a thing and the thing itself is very indirect and arbitrary, involving many steps particular to our biology. For example, when you see the color of something, the full spectral envelope of the EM waves reflecting off of the thing (or sometimes transmitting through it, or emitting from it, etc.) is reduced by the cone cells in the retina to three dimensions (i.e. variables, not speaking of spatial dimensions here), then that information is relayed to the brain through the optic nerves, then the brain translates the three dimensions of color (basically, gradients of red, green and blue) to another color model according to opponent process theory (a yellow-blue continuum, a red-green continuum, and brightness), and then, in some totally unknown way, it makes us experience the result as unaccountable, indescribable and immeasurable qualia (such as the redness of red). And different animals see color in completely different ways due to different cone cells.
The retina also contains a plethora of other types of receptors, such as motion receptors, so we don’t perceive motion as simply the difference between neural inputs at one point of time and at another point of time. And the brain can automatically modify the image in ways that we never know, for example, there’s always a blind spot in our vision from each eye where the optic nerve connects to the eye, yet you never realize it because the brain covers for it unless you’re specifically doing something to reveal it. And people who have done LSD have seen how what they see can appear as real as ever, yet be completely wrong, thus making the whole phenomenon of sight to seem fundamentally like some sort of usually informed hallucination.
And that’s to say nothing of the indirectness and limitations of the process of seeing something that happen outside of the eye-brain system. The spectral envelope of the light that reflects off an object is the indirect result of the chemistry of the object on the surface, the surface texture, and the nature of the light shining on the object, according to twelve or so physical principles. A few other contextual factors can influence how we see color too. Consider this optical illusion:
As you can tell from the bottom image, A and B are actually the same shade of gray.
And not to mention that, at least according to Elon Musk, there are no cone cells (which are the cells that detect color) on the outer parts of the retina, yet we see color in those areas of our vision because the brain extrapolates what it thinks the colors would be in those areas based on the rest of the image.
Then there is the fact that you’re only seeing the unoccluded surface of the object, and that according to the principles of perspective, while the real object is its entire innards. And you’re seeing it from a macro scale, so things appear solid, while on the nanoscale there is no solidity but only fields. And it seems to behave according to classical physics, which is only the mindblowingly counterintuitive physics of the quantum scale as measured in aggregate. So we can see that the mental representation we witness is very fundamentally different from the outside thing.
And, of course, even that scientific description of the outside thing isn’t necessarily absolute reality. You can take measurements, but you can’t measure the relationship between the measurement and absolute reality (supposing there is such a thing as absolute reality; either way, measurements and models can be discovered to be incorrect by future measurements). And measurements themselves have to be interpreted by humans, with all our flaws and subjectivity, and are limited to what kinds of measurements we can imagine given our particular mode of interaction with reality ultimately determined and limited by our biology.
Any sophisticated physicist will tell you that the best physics can do—the only thing physics actually does—is create models that happen to be effective at predicting and controlling things in reality as measured by us. It can’t directly access whatever metaphysical truth underlies our measurements and perception, nor can it infer it with objectivity, since a model can always be shown later to be wrong or incomplete, and either way there’s always the possibility of alternative models that are equally in accordance to physical observation.
An example of a model shown to be wrong and incomplete is Newtonian mechanics, which was later supplanted by general relativity. As an example of an alternative model predicting the same things, the model of gravity that most people accept as curvature of spacetime is only one possible framing of general relativity, invented by Minkowski, not Einstein, and which Einstein was initially opposed to, calling it “superfluous erudition.”
Arguably, it doesn’t even make sense to consider spacetime a thing in itself. Time is just a measure of change, an abstraction somewhat analogous to the measure of distance between positions, and space is just a kind of 3D measure of distance, or the imagination of the potential for an object to have different values for its position property. Empty space is the imagination that an object could have specific position values that none currently have. The mechanics of space is only the mechanics of how material objects interact with each other with respect to their position properties. And you can’t actually detect space, even in principle, so it makes no sense to posit that it’s a thing in itself that can have properties such as curvature.. I wrote more about this here: https://myriachromat.wordpress.com/2020/10/29/space-doesnt-exist/.
Similarly to how science can only create models that effectively predict and control reality as measure, the best our own ideas of reality can be is models our mind synthesizes to predict and control reality as measured by our senses. We have no direct access to absolute reality or metaphysics (assuming such a thing exists), nor can we infer things about it with certainty, for the reasons I explained above in relation to scientific models. Plato’s cave allegory is highly relevant here. And consider that, even if you were able to step outside the cave and see the things that caused the shadows, it’s always conceivable that the reality you’re seeing is only the shadows on the wall of a further metaphorical cave, and so on and so on.
One argument I like to make as to how the thing in itself is not actually unreachable is that that external reality and our own minds are not ultimately separate; they’re both part of the same causal wave pool (we and our minds are actually parts of absolute reality), and our ideas and perceptions of reality are actually patterns from the rest of reality making it inward to our minds through causation. So, there being no absolute separation between the phenomena and noumena, there’s no reason the things in themselves, or the noumena, are absolutely unreachable. I guess this is a weak argument though. There being a causal connection doesn’t necessarily imply that we can understand the entirety of the causal connection, and hence we can’t infer what’s on the other side with certainty.
But does it imply that we can infer the outside reality to a well enough degree, or can the inside reflect the outside directly and accurately enough? Not necessarily. There could be any level of indirection, transformation, convolution, filtering and inconsistency/randomness in the nature of the causal link between the outside and the inside.
More importantly, as I’ve said in a few of my other essays, if external reality is non-ideational (which we suppose it is unless we’re philosophical idealists), then the difference between the nature of external reality and its objects and our ideas about them is more fundamental and hence greater than any other difference we can conceive of. It’s the greatest possible difference. This is because any other two things we can possibly compare and contrast must be things we’re conceiving of, i.e. ideas, otherwise we couldn’t think about them in order to define their differences.
By the way, I say “reality and its objects” above, but I think likely reality isn’t really separated into objects in any objective sense. It’s all one continuous thing, and we only separate it into objects in our perception and ideation (or I guess just in our ideation) because it’s convenient. For example, the chair and the floor beneath it are just one big collection of atoms, and where you draw the line between the two and the fact that you draw a line are arbitrary. You could say that there’s objective separation between the atoms themselves, but according to physics subatomic particles are actually just local excitations in fields that extend throughout all of space. I think any particle also is or has a field that extends outward (however faintly) indefinitely, but I’m not sure.
Furthermore, if any two objects or substances were truly metaphysically separate, then they would have no common language, ruleset, or underlying matrix of causality or even any basis to exist in the same time or space in order to interact with each other. The underlying causal matrix is one giant (maybe unlimited?) pattern of information, and things we consider objects are just selective delineations within this pattern.
By the way, when I say “information” above, it’s just for lack of a better word. I don’t believe reality is made up of information; I believe information is what we get when we measure reality, hence the name “information,” as in “the act of being informed.” Information is purely quantitative, and quantities themselves are empty. They lack qualities and actual substances, and a world without quality or substance can’t possibly give rise to qualia or experience, which are qualitative and perhaps substantive. It can’t even exist, because quantities are just abstractions, like math (see https://myriachromat.wordpress.com/2019/09/21/why-mathematical-platonism-is-silly/), and abstractions don’t exist as things-in-themselves.
Also, information exists as a series or other structure of absolutely separate values, which means bits of information can’t interact with each other for the same reasons absolutely separate objects or substances can’t as explained above.
I guess that’s debatable. I guess you could say the universe is all its information plus the laws that act on it, similar to Conway’s Game of Life, but I find that dubious. How are the laws connected to the information without a more fundamental underlying continuum? (Note that Conway’s Game of Life actually runs on a computer or is otherwise simulated by, or even conceived by or encoded with, something or someone that’s much more than the Game of Life itself.) And not to mention the questions of in what form do the laws objectively exist, why and how they act, and why they are the way they are instead of some other way. I guess those could be problems either way, but they seem to be more tractable in a less simplified, more holistic, more continuous, more substantive, and maybe even unlimited kind of universe or multiverse. And, of course, the problem that pure disembodied information can’t give rise to qualia or experience or even independently exist applies.
I tend to think that the universe is one holistic thing, and the laws and the things they “act on” are not fundamentally separate. Laws are just parts of a physical model that are inferred from what’s ultimately all patterns of measurement. I guess if laws are not truly separate from what they “act on,” then this implies that the laws (which actually are just parts of potential models) are ultimately no less complex or whimsical than the universe itself. (If you don’t think it’s rational to say the universe is whimsical, just replace “whimsical” with “random” or “stochastic.”)
Anyway, to get back to the original subject, I wanted to show that it’s not only our eyesight that’s indirect and biology-specific. Take smell for example. The smell of a rose isn’t really a property of the rose itself. The rose releases trace amounts of chemicals into the air, some of which land in the olfactory part of the nose and temporarily bind with other chemicals in the olfactory organ, which then sends signals to the brain, which ultimately somehow generates an unaccountable, indescribable and immeasurable qualia from that information. (Yes you may be able to describe a smell, but only in terms of other smells that the other person has already experienced.) Some chemicals we can’t even smell at all, and some other animals can smell such chemicals. A similar description to the above can be applied to the sense of taste.
Now let’s move on to hearing. The vibration of the air itself exists as compression waves that could be graphed as one long complex waveform, but the cochlea in the inner ear transforms that information from the time domain to the frequency domain. What it sends to the brain isn’t waveforms, but intensities of various frequency components. It applies something like the Fourier transform to the waveform. If you add up sine waves based on all the various frequency values (which is the reverse Fourier transform), you reconstruct the original waveform, so all the data from the original is in the frequency representation. So you could say you’re hearing most of the actual vibrational pattern, but it’s not like the brain is actually performing this transformation, so the nature of the sound you hear is drastically different from the nature of the original vibration.
And, of course, our hearing is limited to a particular frequency range, approximately 20 hertz to 20,000 hertz, or around 14,000 hertz for people over middle-age, or something like that. Sounds (as actual vibrations, not as what you hear—the term is bit ambiguous) can exist well beyond those limitations, and other animals have different ranges of perception. We also judge relative pitch on a logarithmic scale instead of a linear one, and perceived volume is much greater for high pitches than low pitches than the actual amplitudes, on a logarithmic scale. And, of course, as with the other two senses, the qualia we ultimately experience is unaccountable, indescribable (except by relating qualities of sounds that the other person has already experienced) and immeasurable. All such qualia are probably completely arbitrary, and could be different for different animals.
They could conceivably even be different for different people. One of the most common questions I get on Quora is “Does everyone see colors in the same way?” There’s no way of knowing for sure. Just because we call the same colors the same names doesn’t mean we experience them the same way. We just learn by association that X experience (which is ultimately caused by the same light frequencies) maps to Y name. There are neurobiological reasons to think we all perceive color the same way, though, as well as the commonalities in what different emotions people associate with different colors (for example, blue=calmness).
A naive realist might say that the difference between the smell and the chemicals the rose emits is one of levels of description, but that doesn’t really make sense because the smell of the rose could be different for different species. Also, if the smell were actually something that surrounds or belongs to the rose as we intuitively think, then it would still be there when we’re not there smelling it. But we know it’s not, because the qualia or smell of the chemicals, which are what really surround the rose and and are there even when we’re not, is known to be purely a product of the brain (or I would actually say the brain/mind combination, as I don’t think mind reduces to brain processes. See https://myriachromat.wordpress.com/2018/04/13/notes-on-science-scientism-mysticism-religion-logic-physicalism-skepticism-etc/#Emergent).
One further note is that, if philosophical idealism is true, and/or psychic perception is possible, or perhaps some kind of spiritual unity with the cosmos is, then the bulk of the above arguments against reaching the noumena doesn’t necessarily hold up. I’m a fan of philosophical idealism (see https://myriachromat.wordpress.com/2020/02/07/why-im-an-idealist/), and I believe psychism is very real. Because I’ll be seen as irrational for saying that psychism is real, I’ll take some time to explain myself here.
Welp, anyway, I guess that’s all I have to say about the unknowability of the noumena.