Kant’s things in themselves, which correspond to Locke’s things themselves,

Kant’s antinaturalistic, transcendental idealism rests on a tacit naturalistic basis. — Tomida

Of course, Kant is a man of his time, and the debate of his time was between empiricists and rationalists. But to equate his starting point with Locke seems risky to me. In empiricism the concept of object is formed empirically (whether it is mathematical or not). In Kant it predates sensations. Without a previous concept of cause the game with the data of the senses would be chaotic.

If I remember correctly, Locke introduces some rationalism in his empiricism when he considers the mathematical world of things universally factual by giving them a material body: atoms. This is another matter, but it is also contrary to the Kantian starting point.

Well, I'd rather not take too many chances with Locke who I know only from textbooks.

But why not Locke? — mask

I don't know much about Locke, except his (relative) liberalism. I get the impression that he's much simpler than Kant. If you want present the case for Locke, I would like to read it.

Where is mathematics then? It seems to me that as a matter of experience mathematics is relatively uncontroversial. We all agree that there are an infinity of primes. It seems we infer a shared hard-wired mathematical faculty from this consensus. — mask

The idea of the universality of mathematics had to be abandoned with non-Euclidean alternative mathematics. At first they were considered as mathematical "eccentricities", but they had to be taken seriously when the theory of relativity took them up. The situation today is as follows: pure mathematics works on diverse paths and theoretical physics takes the way it is interested in. Sometimes it is the demands of physicists that open up new mathematical paths. The idea of a single, infallible mathematical path is popular but not correct.

Otherwise, Kant was right about knowledge a priori. Just it is not so much a priori than he thought.

Thank you for the links.

Does Kant really think there are basketballs out there? — mask

In my opinion what makes Kant attractive is that he stands between subjective idealism and dogmatic realism. The world of phenomena is somewhere between pure subjectivity and pure reality. It exists outside the mind, but it does not exist apart from the mind.

The truths of Euclid seem to depend on shared practices. Trying to ground science on an individual mind seems iffy. What does Kant assume without realizing it? — mask

There is a part of Kant's theory of mathematics that is fully valid: mathematics are constructions that are imposed a priori and then justified by experience. There is another part that is outdated: mathematics is universal. Since the emergence of non-Euclidean mathematics and its use in modern science, this is unsustainable.

I would like the debate to shift to Heidegger. I tried to read Being and Time and found it too cumbersome, so I stopped. I only know about him through third parties too involved in controversies against or in favour of him.

Outward objects in themselves are perceived. — Mww

Your mistake was here. Things in themselves are not perceived, only thought.Let us see the whole paragraph:

"The aim of this remark is only to prevent one from thinking of illus-
trating the asserted ideality of space with completely inadequate exam-
ples, since things like colors, taste, etc., are correctly considered not as
qualities of things but as mere alterations of our subject, which can even
be different in different people. For in this case that which is originally
itself only appearance, e.g., a rose, counts in an empirical sense as a
thing in itself, which yet can appear different to every eye in regard to
color. The transcendental concept of appearances in space, on the con-
trary, is a critical reminder that absolutely nothing that is intuited in
space is a thing in itself, and that space is not a form that is proper to
anything in itself, but rather that objects in themselves are not known
to us at all, and that what we call outer objects are nothing other than
mere representations of our sensibility, whose form is space, but whose
true correlate, i.e., the thing in itself, is not and cannot be cognized
through them, but is also never asked after in experience". (B45)

Underlined is mine.

What calls you to confusion is probably the expression of what is in itself "in empirical" sense. Kant is not defending here his own doctrine, but he is exposing English empiricism that he will criticize in the following lines: Sens data are always subjective ("different" for each of us) and cannot give account of the very thing in itself. "What we call objects" (a pencil, a wolf) are only representations of sensibility (that is to say, phenomena). But thing in itself cannot be "cognized" so.

Obviously not an easy subject, so many distinctions to keep in mind. — waarala

It should be noted that Kant wrote in Old German. This leads to different translations. The one from Cambridge University Press (available online) seems particularly clear to me, but English is obviously not my mother tongue.

When the face in the toast is the focus of attention, the toast itself fades to background) — Mww

I'm afraid I don't understand the example of the toast. This raises a question about your conception of the thing in itself (noumenon). The face on the toast is just a phenomenal illusion. Things in themselves refer to objects such as substance, God, cause, soul, etc. that have no appearance. This is what defines noumenon by opposition to phenomenon.

↪David Mo
https://youtu.be/pYRLapWBqJY — Wayfarer

Thank you.

In that chapter on noumenon Kant once refers to categories as noumena. — waarala

This has no sense for me. Could you quote Kant's exact sentence, please?

One meaning of noumenal is ‘object of pure thought’ or actually of nous. In that sense — Wayfarer

Etymologically, yes. But that compromises us with Greek philosophy, which is what Kant wants to criticize.

Are you familiar with philosopher of science Michel Bitbol? — Wayfarer

Sorry, no. Can you point me to a link on the Internet? I read in French.

“...objects are quite unknown to us in themselves, and what we call outward objects, are nothing else but mere representations of our sensibility...”
(B45)

Simple substitution, object in itself for thing in itself. It is done by the author repeatedly. Please show how my argument is wrong. — Mww

In this paragraph Kant is criticizing the "ordinary" representation of things in themselves, purely empirical. His criticism begins from "But if we consider..." The idea is that the in thing itself cannot be reached through the generalization of the senses.

I'm not familiar with his writings. Can you, or anyone else, explain why Kant should be considered important for understanding QM or science generally? — Andrew M

See previous comments, please.

eft is the question of Kant and modern science. For the purposes of modern science, Kant is usually ignored. But there's also an inclination to dismiss his thinking, and imo that's an error. What his thinking is about, is things that are perceived, or that reason gives us. — tim wood

Welcome, Tim.

I agree. The fathers of 20th' Scientific Revolution were obsessed with Mach, Hume or Plato and let in oblivion Kant (with d'Espagnat exception, but he was not a father, just an older brother). Maybe Kant was too attached to Newtonian science that they were trying to overcome. But if this was the case, they got muddled with Kantian details and overlooked Kantian principles.

What it seems important as principle in Kant is the regulative use of the reason. That is to say: physics principles are a priori because they come from a priori conditions of our knowledge, not being things in themselves. This links with Kuhnian concept of paradigm and with quantum paradoxes of measurement, relativity, etc. We live a world mediated by the categories of our way of thinking.

OK, but per consciousness, almost everybody in quantum mechanics denies that consciousness causes collapse. — Andrew M

Yes. But in quantum mechanics (not philosophy) the subjective means the problem of measurement, that is to say, the fact that some objects cannot be known -or even exist- independently of the fact to be measured. May be "intersubjective" would be more accurate, but usually they are called "subjective". In any case not "objective".

Noumenon = relative to appearance. — Xtrix

Noumenon is just the opposite of appearance in the sense that appearance is the phenomenon. We can see houses (phenomenon). We cannot see God (noumenon). In this case appearance is known by sight. If "relative" means the opposite, well, but it is a strange way to say it.

The concept of limit is not trivial. It is the battlefield of any philosophy: What can I know?

Yeah.....just think of how many meanings can be changed merely by gutting a quotation. — Mww

Kant is not always clear, but this paragraph (B310) is.

In the first sentence he defines what he means by a problematic concept.
A concept is problematic when it is not contradictory, but pretends to refer to a reality that is not cognizable.
In the second sentence defines noumenon: the concept of a thing in itself that is not contradictory but escapes the unique intuition possible: sensible intuition. That is to say, noumena are problematic. [You may think here there is a difference: noumena are the concepts and things in themselves are its reference. In reality Kant uses the name noumenon in both senses. In the twelfth line he speaks of "phenomena" as objects outside of the appearances, that is the same way he speaks of things in themselves.]
In the subsequent lines to the end he reinforces the idea of emptiness of noumena (according to the Kantian principle that concepts without intuitions are empty) and concludes that, even being empty, they have a double utility. They show that they cannot been get by sensibility [against English empiricism -Hume] and so they mark the limits of intellect that cannot be overstepped.

I think the seeming contradiction you have marked is due to the two different uses of the word "noumenon" that Kant envisages here. Problematicity summarizes it and its utility.

Anyway, Kant only say in these sentences that noumena cannot be explained by sensibility because they point to an impossible-pure knowledge of metaphysical entities.

The two iterations are very far from being consistent with each other, — Mww

That seems to be the case if you have not grasped the concept of problematic, which is essential to the understanding of the paragraph.

(with no implication of consciousness or subjectivity in either system) — Andrew M

I said that the problem of subjectivity in measurements was raised, not that everyone had the same answer. And subjectivity does not only mean consciousness, but also relativity with respect to measurement, something that nobody or almost nobody denies in quantum mechanics: the collapse of the wave function.

Heisenberg deals with the subject especially in chapters 8 and 10 of the book you quote. His conclusion is not as emphatic as you seem to indicate with your quotation. Here is another one (the translation is mine):

"But atoms or elementary particles themselves are not
so real; they constitute a world of potentialities or
possibilities rather than one of things or facts". (Final lines of chapter 10).

"Understanding accordingly limits sensibility, but does not thereby extend its own sphere. In the process of warning the latter that it must not presume to claim applicability to things-in-themselves but only to appearances". (A288) — StreetlightX

Let's take it one step at a time:
Your first quotation says nothing of distinction noumenon- thing in itself. Only says that intellect is not appliable out of world of senses (phenomena-appearances).
"Noumena are 'appearence-relative', and only appearence-relative" is an invention of yours. Noumena is not even mentioned.

Second step

"If we want to call this object a noumenon because the representation of it is nothing sensible, we are free to do so. But since we cannot apply any of our concepts of the understanding to it, this representation still remains empty for us, and serves for nothing but to designate the boundaries of our sensible cognition" — StreetlightX

According with your first quote, Kant says that intellect cannot understand the world from beyond phenomena. Therefore the attempts to give a content to this world (noumena) are empty. Nothing can be said of things in themselves other than they might exist.

Once again nothing is said of the difference between noumena and thing in itself.
Your comment has no sense: "limitations of understanding" es exactly what impede it to go beyond phenomena. What should not extend beyond sensitivity is not limits, but understanding. "Does not" is singular: it refers to understanding; not "the limits", plural. I'm sorry, but you misread that.

Third step.

but that nevertheless seems to us to be a way in which the object exists in itself (noumenon), — StreetlightX

Whether it is a mistake or not, what this sentence does is to equate the thing that exists in itself with the noumenon The error does not consist in this equality (expressed with the use of a parenthesis, which the parenthesis gives for a fact), but in the idea that the object of understanding, the thing in itself or noumenon can be considered without taking into account the kind of intuition that makes it accessible or not.

Summarizing: Your quotes have nothing to do with matching noumena-thing in itself. Only one mentions both like they are the same. Besides, they contain some reading mistakes.

Well, I'll say goodbye with a quote in which Kant identifies noumenon and thing itself directly:

"...a way in which the object exists in itself (noumenon), without regard to the intuition to which our sensibility is limited". (B346)

Not at all. I've repeatedly acknowledged that noumena can be understood as things-in-themselves. Only that the converse does not hold in all cases. — StreetlightX

Can you quote Kant to demonstrate that distinction?

You keep stringing the two together without argument. — StreetlightX

Does this one work?

"The concept of a noumenon, (...) as a thing in itself" (B310)

Not only I, but other participants in the forum have already given you several texts in which Kant identifies noumenon and thing in itself in the same way: what falls outside the conditions of understanding, but you ignore them.

This makes of Kant an idealist in the Berkeleyian sense, — StreetlightX

If the concept of imbecility disappeared, imbeciles wouldn't disappear. Unfortunately. You keep confusing the concept of noumenon or thing in itself with the existence of things.

"The concept of a noumenon is thus a merely limiting concept, — StreetlightX

Here you see:

"Now the doctrine of sensibility is at the same time the doctrine of the
noumenon in the negative sense, i.e., of things that the understanding
must think without this relation to our kind of intuition, thus not
merely as appearances but as things in themselves, but about which,
however, it also understands that in this abstraction it cannot consider
making any use of its categories, since they have significance only in re-
lation to the unity of intuitions in space and time, and can even deter-
mine this unity a priori." (CP308) [Emphasis mine]

If the sensitivity disappears, the concept of the thing itself also disappears, because it is defined in contrast to the phenomena, which Kant also calls appearances. You see that in this text Kant opposes the thing itself to the phenomenon (appearances). That is, the thing itself is the same as the noumenon: that which is opposed to the phenomenon.

I think you are confusing Kant's words: He says that noumenon in the negative sense is nothing more than the concept that specifies the limits of knowledge, as opposed to noúmeno in the positive sense, which seeks to go beyond them (classical metaphysics). It does not say that the only being of the noumenon is in the understanding.

He says that the concept of noumenon "only" is limiting. Not that noumenon is just a concept.

By their respective relation to the subject! I keep repeating this - in fact it was the first thing I said here: noumena are the limit of sensibility. They are only defined in relation to our capacity for knowledge. Things-in-themselves, by contrast, are defined by having no relation to our capacity for knowledge. The difference between not-X and not X. — StreetlightX

And when Kant says that the thing itself cannot be known, does he not put it in relation to our knowledge? To say that it marks the limit of our knowledge is the same as saying that it is outside our knowledge.
It's not true that numena are "only defined" by their relationship to knowledge. Noumenon is defined as "the way we call things in themselves". Two ways of calling the same thing!

OK, but that's all phenomena as well, in my view. It's all experience — Xtrix

This is your way of saying it, not Kant's. Besides, there's a difference between imagination and the world of noumena in Kant. In the imagination, sensitive objects are mixed up in the wrong context. The fantastic entity could be perceived in strange circumstances, outside of normal life. This is not the case with noumena because they are outside of any perceptible circumstance: outside of space and time.

One might say: noumena are things-in-themselves under the aspect of the transcendental subject. However, get rid of the transcendental subject, and one similarly 'gets rid' of noumena - but not things-in-themselves, which are subject-independant. — StreetlightX

It's the same thing even if you call it by different names. "Noumena" is another way of saying "thing in-itself". If the subject disappears, the name disappears, not the named thing.

That's an interesting statement in the context of this thread. The relevant question is whether it points to a subject/object duality or to an underlying symmetry. That is the measurement problem. — Andrew M

I have not understand what symmetry you refer.

Anyway, Bohr, Einstein, Heisenberg et alia thought that quantum mechanics posed a problem of subjectivity to science. Bernard d'Espagnat (https://en.wikipedia.org/wiki/Bernard_d%27Espagnat) devoted an article to the importance of Kant to understand quantum mechanics.

Representations of our sensibility is an affect on our senses. An affect on our senses is a perception. A perception requires what we call an outward object. Outward objects are outward things. Outward objects in themselves are things-in-themselves. Outward objects in themselves are perceived. things-in-themselves are perceived. That which is merely perceived is unknown to us. Things-in-themselves are unknown to us. — Mww

Your argument is wrong. To think that an undetermined "something" has caused A is not the same as knowing the cause of A. Moreover, Kant says countless times that we cannot perceive things in themselves. This is the main point of CPR.

though we cannot know these objects as things in themselves, we must yet be in a position at least to think them as things in themselves; — Xtrix

Kant distinguishes between knowing and thinking. We can think about infinity, but not know it. Knowing implies defining and grasping its existence.

Things we think aren't phenomena? "God" and "soul" and the "Universe" are not phenomena or knowledge? Than how can you speak about them at all? — Xtrix

Similarly we talk about rivers of honey or flying horses. Mixing concepts or using meaningful words in wrong contexts where they mean nothing.

Examples of such intelligible objects would be what exactly? — Xtrix

God, soul, Universe as Totality... It can be thought, but not known. It is thought as a mere boundary of what I cannot know. My intelect push me to it, but knowledge fails because only phenomena can be known.

"The concept of a noumenon, i.e., of a thing that is not to be thought of as an object of the senses but rather as a thing in itself (solely through a pure understanding), is not at all contradictory; for one cannot assert of sensibility that it is the only possible kind of intuition. Further, this concept [noumenon] is necessary in order not to extend sensible intuition to things in themselves, and thus to limit the objective validity of sensible cognition(...) . In the end, however, we have no insight into the possibility of such noumena, and the domain outside of the sphere of appearances is empty (for us)(...)The concept of a noumenonf is therefore merely a boundary concept, in order to limit the pretension of sensibility, and therefore only of negative use". (Kant, Op. cit. p. 362)

I think Kant is clear here.

I was advising against relying on secondhand material. I believe you posted a quote from wiki not me. — I like sushi

I am sorry. I believed this advice was yours.
"Wiki and stanford or britannica ency. are all decent ways of finding items of interest though."

Then you will agree that the reference to Kant's work that I have given is the right one for engage a serious discussion:

"On the ground of the distinction of all objects in general into phenomena and noumena".

Do you agree?

Which section? Schopenhauer believed Kant intentionally obscured his message to avoid being harassed by christians. I know Schopenhauer much more thoroughly than Kant, and I'm afraid I probably use his interpretation (right or wrong). — frank

I don't know what Schopenhauer was exactly referring to. But some basic things are clear and distinct. For example:

"'The transcendental use of a concept in any sort of principle consists in its being related to things in general and in themselves; its empirical use, however, in its being related merely to appearances, i.e., objects of a possible experience". (Op. Cit. p. 356).

It is clear, it is not?

NOTE: Kant is sometimes difficult to read, but we don't need exaggerate.

I really don't want to get into an argument about "what Kant said" because that's not really as interesting discussing philosophy. So it may be that we'll end up saying we have two different impressions of what Kant said? — frank

I would say that here are some obviously wrong interpretations of Kant. Go to the section on CPR that I recommended in my previous commentary and you will see why.

Wiki and stanford or britannica ency. are all decent ways of finding items of interest though. — I like sushi

I don't think that's advisable. If you want to get an exact idea of what Kant thinks, go to the Cambridge University Press edition of the Critique of Pure Reason (available online in pdf format). In the section "The Transcendental Doctrine of the Power of Judgment (Analytic of Principles); Third Chapter:
On the ground of the distinction of all objects in general into phenomena and noumena" (p. 354ss)
Here you will find a clear explanation of what a noumeon is, its identity with the thing in itself and its inaccessibility to human understanding.

Maybe this quote solve the problem of noumenon and thing in itself

“Noumena in a positive sense are simply noumena as Kant originally defined that notion in the A edition: objects of an intellectual (non-sensible) intuition. The negative concept of noumena, however, is simply the concept of objects that are not spatiotemporal (not objects of our sensible intuition, namely space and time). But then it follows that things in themselves are noumena in the negative sense, retrospectively clarifying the passage from the A edition quoted immediately above, where Kant seems to draw from the “Transcendental Aesthetic” the conclusion that there are noumena: the concept of appearance requires that something appears, and this must be a negative noumena”.

Stang, Nicholas F., "Kant’s Transcendental Idealism", The Stanford Encyclopedia of Philosophy (Winter 2018 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/win2018/entries/kant-transcendental-idealism/>.

ou said phenomenon in your initial post. I corrected you, which you acceded to.

And in any case, the quote you provided in this post says nothing about the in itself. — StreetlightX

Right. I've already rectified it.
Isn't calling the pruychos "bolontes" relating the pruychos to bolontes? Hmm. One of us has a problem with English and I'm afraid it's not me this time.

Lmao they are opposites. — StreetlightX

From CPR:
"it also follows naturally from the concept of an appearance in general that something must correspond to it which is not in itself appearance, for appearance can be nothing for itself and outside of our kind of representation; thus, if there is not to be a constant circle, the word "appearance" must already indicate a relation to something the immediate representation of which is, to be sure, sensible, but which in itself, without this constitution of our sensibility (on which the form of our intuition is grounded), must be something, i.e., an object independent of sensibility. Now from this arises the concept of a noumenon, which, however, is not at all positive and does not signify a determinate cognition of something in general, in which I abstract from all form of sensible intuition". (A251–2)

Where is the opposition? In itself and noumenon are the same: out of any form of sensibility or cognition.

I'm sorry I don't have the Critique of Pure Reason at home in English, but it's a major mistake to dissociate noumenon and thing in-itself in Kant. For example, one of Kant's reference manuals (Justus Hartnack: Kant's Theory of Knowledge) in its chapter 5 ("Phenomena and Noumena"):

"But from the fact that we call 'phenomena' what is sensed in space and time, it follows that it has to make sense to talk about what is not a phenomenon and what Kant calls the thing in-itself or 'noumena'." (My translation Spanish-English)