So the indirect realist believes that what we can't see is what is real? — Wayfarer

Not necessarily. Just because I cannot see a unicorn doesn't mean that I think unicorns are real.

From Wikipedia Direct and Indirect Realism

Indirect realism is broadly equivalent to the scientific view of perception that subjects do not experience the external world as it really is, but perceive it through the lens of a conceptual framework.
Direct realism postulates that conscious subjects view the world directly, treating concepts as a 1:1 correspondence.

I see the colour red, yet the colour red doesn't exist outside my perception of it. I do have, however, the fundamental belief that there is something in the world that caused me to perceive the colour red.

My seeing the colour red is a real experience, and I believe that there is also a real something in the world that caused my seeing the colour red.

For example, you may feel a sharp pain in your hand caused by a bee sting. I don't think anyone would argue that the pain and the bee sting are the same thing and thereby interchangeable. Both are real, yet different things. One is the effect and the other is the cause.

Isn't it fairly simple that our perceptual abilities, and also our intellectual abilities, are limited in some ways, so that what the world is outside of those bounds can't be known by us? — Wayfarer

Exactly. This is the point that Kant is making in the CPR, and as an Indirect Realist, something I totally agree with.

However, I don't think that the Direct Realist would agree with you.

How many external worlds do you have, and which one is the real world? Why do you need more than one world? — Corvus

There are many uses for the word "world". There is the world of dance, the world of science, the world of literature, the world inside our minds, the world outside our minds, etc.

One word having several uses is in the nature of language.

What is real? Is the thought of a mountain any less real than the mountain itself?
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What is the unknowable Things in themselves that exist outside you exactly mean? What are they? — Corvus

Kant wrote in Prolegomena section 32:

"And we indeed, rightly considering objects of sense as mere appearances, confess thereby that they are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, viz., the way in which our senses are affected by this unknown something."

We perceive appearances, phenomena, in our senses. We may see the colour red, feel a sharp pain, taste something sweet, smell something acrid or hear a grating noise.

We have the fundamental belief that something caused these phenomena. But we don't perceive what caused these phenomena, we only perceive the phenomena.

The cause of the phenomena is irrelevant in our experience of the phenomena, in that whether the sharp pain was caused by a bee sting, a sewing needle or a thistle plays no part in the nature of our experience of a sharp pain.

The cause of the sharp pain can be called a Thing in Itself, and even if unknowable, has no bearing on the nature of the actual experience of a sharp pain. Even if we knew what the cause was, this would not change the phenomena that we had perceived.
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So Things-in-themselves exist outside you, but it also exists in your mind? Are they the same Things-in-themselves? Or are they different entities? Are they visible or audible to you? Can you touch them? If they are not perceptible, then how do you know they actually even exist? — Corvus

My belief is that Things in Themselves have an ontological existence outside us even if a particular Thing in Itself is unknowable.

Kant uses Transcendental Reasoning on what we do know, appearances, to conclude that Things in Themselves must exist outside us.

Therefore, "Things in Themselves" have an ontological existence outside us, and they exist as thoughts inside us.

There are many things outside us that are not directly perceptible through the senses yet we reason exist. For example, gravity.

Now the question goes back to Thing-in-itself. Is the Thing-in-itself something in the mind or does it exist outside of the mind? If outside, then would it be in the external world, or some other world totally separate from the external world? — Corvus

It depends what you mean by "external world". There is the external world that I perceive as Appearance, and there is the external world outside me that I cannot perceive that is causing these Appearances.

Kant wrote in B276:

"The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me."

Kant wrote in Prolegomena section 32:

"And we indeed, rightly considering objects of sense as mere appearances, confess thereby that they are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, viz., the way in which our senses are affected by this unknown something."

To my understanding of Kant, Appearances are affected by unknowable Things in Themselves that exist outside me.

However, as we can also think in general terms about Things in Themselves using Transcendental Reasoning on Appearances, thoughts about Things in Themselves exist in the mind.

I do believe in only one world i.e. the physical world. I was asking about the external world in the Refutation for the Idealist you quoted. — Corvus

In B276 Kant refers to objects existing outside any human observer: "The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me."

You say that you see only one world, it is empirical, it is physical, it is external, it is not internal and it is not Mind-Dependent.

Are you:

An Indirect Realist who believes that the objects they see are only a representation of different objects that exist outside the observer in a non-mental world?

A Direct Realist who believes that the objects they see are the same objects that exist outside the observer in a non-mental world?

A Berkelian Idealist who believes that the objects they see are the same objects that exist outside the observer in a mind?

A Solipsist who believes that the objects they see only exist inside their own mind?

How does one know one's own existence "determined in time" without yet being sure of the external world? — Corvus

I assume you know your own existence within time, yet you don't seem to believe in an external world.

As you wrote:

I don't see it anywhere. Even with binoculars, telescope and magnifying glasses and microscopes, there is no such a thing as a Mind-independent world. There is just the empirical world with the daily objects I see, and interact with. That is the only world I see around me. Nothing else. — Corvus

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Should the indirect realist not check the argument of the Refutation for the Idealism for any logical obscurity before accepting it? — Corvus

I'm sure they do. I know I have.
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It would be likely to be a biased opinion. It is better to look at the original work first, and then various other commentaries rather than just relying on one 3rd party commentary source. — Corvus

As Kant's philosophy is extremely complex and notoriously difficult to understand, I think the sensible approach is first to read various commentaries and then look at the original material.

You cannot prove the existence of the objects in space outside of you by simply saying you are conscious of your own existence. — Corvus

In B276, Kant starts his proof with "I am conscious of my existence as determined in time."

He doesn't start his proof with "I am conscious of my existence".
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Not contradictory, but not making sense either. — Corvus

Kant's Transcendental Idealism and Refutation of Idealism B276 make sense to an Indirect Realist but perhaps not to a Direct Realist.
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Do you have the CPR reference for backing that points up? No Wiki or SEP, but CPR. — Corvus

For posts on the Forum, the SEP as source information is more than adequate.

Welcome to the Stanford Encyclopedia of Philosophy (SEP), which as of Summer 2023, has nearly 1800 entries online. From its inception, the SEP was designed so that each entry is maintained and kept up-to-date by an expert or group of experts in the field. All entries and substantive updates are refereed by the members of a distinguished Editorial Board before they are made public. Consequently, our dynamic reference work maintains academic standards while evolving and adapting in response to new research. — https://plato.stanford.edu/about.html

You seem to think a world is some logically reasoned object. — Corvus

The Empirical World inside us we know through our sensibilities. The Mind-Independent World outside us we know through Transcendental Reasoning about the Empirical World inside us.

A photograph is to show visual image, not the form of reason. It is nonsense to say that a photo can only show the form of reason. — Corvus

The Mind-Independent world can only be known using transcendental reason.

Reasoning is a logical connection between several strands of an argument, for example, the syllogism. A syllogism has the same form, in which a conclusion is drawn from two premises, regardless of its content.

For example, i) all men are mortal, Socrates is a man, therefore, Socrates is mortal ii) all dogs are animals, all animals have four legs, therefore all dogs have four legs.

As a syllogism can only have content when its form is complete, reason can only have content when its logical form is complete.

A single photograph as a single premise is only one part of a logical sequence within a reasoned argument, and as its logical form is incomplete, it cannot be said to have content.

This is why a single photograph cannot show a Mind-Independent World, as knowledge about a Mind-Independent World requires Transcendental Reason, and reason in order to have content requires a complete logical form. A single photograph as a single premise cannot have the necessary content for a Transcendental Reason as it is an incomplete logical form.
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In that case, would it be the case that you have been mistaken Kant's refutation of Idealism as Kant's TI? — Corvus

No.

From the Wikipedia article Transcendental Idealism

Transcendental idealism is a philosophical system founded by German philosopher Immanuel Kant in the 18th century. Kant's epistemological program is found throughout his Critique of Pure Reason (1781). By transcendental, Kant means that his philosophical approach to knowledge transcends mere consideration of sensory evidence and requires an understanding of the mind's innate modes of processing that sensory evidence.

In his Refutation of Idealism is his Theorem "The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me" B276.

These are not contradictory positions.
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In that case, should it not be a representation of the empirical world in your mind, rather than an internal world inside you? — Corvus

Of course, that's why in our internal world is a representation of the external world.
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As an aside, the Thing in Itself has nothing to do with God, the soul or freedom.

There is only one world called the empirical world, and it is outside the mind. Appearance is from the empirical world....................When I see a book in front of me, it is via the appearance or phenomenon from the object (the book) in the empirical world (outside of the mind).................. The physical objects in the empirical world also continue to exist through time.................There is no such thing as an internal world. In your mind, there are only perceptions. — Corvus

I wrote that there are different "Worlds". One exists within the mind, an "Empirical World", and the other exists outside the mind, a "Mind Independent World"

From the Merriam Webster Dictionary, "empirical" means i) originating in or based on observation or experience, ii) relying on experience or observation alone often without due regard for system and theory.

"Empiricism" means i) the practice of relying on observation and experiment especially in the natural sciences ii) a tenet arrived at empirically.

So far, the word "empirical" refers to what exists in the mind rather than what exists outside the mind, inferring that an "Empirical World" also refers to what exists in the mind rather than what exists outside the mind,

The SEP article on Rationalism vs Empiricism also distinguishes between an external world and an internal world

The dispute between rationalism and empiricism takes place primarily within epistemology, the branch of philosophy devoted to studying the nature, sources, and limits of knowledge. Knowledge itself can be of many different things and is usually divided among three main categories: knowledge of the external world, knowledge of the internal world or self-knowledge, and knowledge of moral and/or aesthetical values.

You say that there is only "one world", and in this "one world" physical objects continue to exist through time. IE, whether one million years ago or one million years into the future. But we know that one million years ago there were no humans, meaning that in this "one world" you are referring to, humans are not a necessary part.

So how can this "one world" be an "empirical world" if humans are not necessarily there to observe it?

I am not sure if a philosophical topic which is totally severed from the Empirical world has a meaning. Are you? — Corvus

The Empirical World is the world of Phenomena, and the Mind-Independent World is the world of Things in Themselves.

I am sure that the Mind-Independent World is of philosophical interest.

Whether Kant intended the (negative) noumena as part of the Empirical world or the Mind-Independent World is ambiguous. Sometimes he treats the noumenon as a part of the Empirical World, and sometimes he treats the noumenon as part of the Mind-Independent World. In classical philosophy, Plato etc, the noumenon is part of the Empirical World.

From Wikipedia Noumenon

In Kantian philosophy, the noumenon is often associated with the unknowable "thing-in-itself" (German: Ding an sich). However, the nature of the relationship between the two is not made explicit in Kant's work, and remains a subject of debate among Kant scholars as a result.

As regards tables and chairs, we perceive them in our Sensibilities as Phenomena. If they exist as Things in Themselves in a Mind Independent Word then they are unknowable, meaning that we can never know whether they do or do not exist. But we do know about tables and chairs, meaning that our knowledge about them must have come from our Empirical World, as Ideas or Forms, ie as Noumena.

We can only know about Things in Themselves in general in a Mind Independent World using transcendental reasoning, in the same way as used by Kant in his Refutation of Idealism in B275.

If you can see it, can you take a photo of a Mind-independent world, and upload here? — Corvus

As a Mind-Independent World can only be known by transcendental reason, and as a single photograph can only show the form of reason and not its content, a single photograph can never show a Mind-independent World.
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This thread is for reading Kant's CPR. Why try to show Berkeley's Idealism is incorrect? — Corvus

Kant refers to Berkelian Idealism in B275, which is part of his purpose in the Refutation of Idealism.

Idealism (I mean material idealism) is the theory that declares the existence of objects in space outside us to be either merely doubtful and indemonstrable, or else false and impossible; the former is the problematic idealism of Descartes, who declares only one empirical assertion (assertio), namely I am, to be indubitable; the latter is the dogmatic Idealism of Berkeley, who declares space, together with all the things to which it is attached as an inseparable condition, to be something that is impossible in itself, and who therefore also declares things in space to be merely imaginary.

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In summary how did you manage to cram in the whole universe into inside your mind? — Corvus

Because a "mountain" as a representation in the Empirical World within the mind is different in kind to a "mountain" weighing one billion tonnes in a Mind-Independent World outside the mind.

Even with a binoculars, telescope and magnifying glasses and microscopes, there is no such a thing as a Mind-independent world.............If you can see it, can you take a photo of a Mind-independent world, and upload here? — Corvus

Even if I uploaded a photo of a Mind-Independent World, the Solipsist wouldn't believe it.

Where is a Mind-independent world? — Corvus

All around us. It existed before us and will exist after us.
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Again what is the point even talking about something which is unknowable? — Corvus

To show that Berkelian Idealism is incorrect.

In fact, for the day to day survival of humans, there is no necessity to know more than what is perceived in our Empirical World of Phenomena. Any transcendental thought about a Mind-Independent World is out of philosophical interest only.
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If it was unknowable, then how did you know it was unknowable? — Corvus

Kant wrote that Appearances are based on Things in Themselves, even though Things in Themselves are unknown.

And we indeed, rightly considering objects of sense as mere appearances, confess thereby that they are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, viz., the way in which our senses are affected by this unknown something. — Prolegomena, § 32 — https://en.wikipedia.org/wiki/Thing-in-itself

Kant uses a Transcendental Argument in the Refutation of Idealism to prove his Theorem that Things in Themselves exist, even though what they are is unknown.

"The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me." B276

No one was claiming Kant said the Thing-in-itself, something that is knowable. — Corvus

When I see the book in front of me, I know the book. I know it is in blue colured cover, it is a paperback book, the title of the book is "CPR" by Kant. I cannot be wrong on that. It is the truths I know about the book in front of me. I don't need to worry anything about Thing-in-itself book of CPR. There is no such thing as Thing-in-itself CPR book, but there is a CPR book in front of me. — Corvus

All this is true, in that you see the book in your Empirical World, the world that exists as Appearance in your Sensibilities. The world as Phenomena.

However, what you are not seeing is any world outside these Phenomena.

In a world outside these Phenomena are Things in Themselves, which are unknowable, and as unknowable, cannot even be thought about.

Even if books existed in a Mind-Independent world, as Things in Themselves they would be unknowable, and being unknowable, we couldn't even know whether they existed or not.

In Kant's Refutation of Idealism, he proposes the Theorem in B276: "The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me."

Yes, Kant as a believer in Realism does believe that a Mind-Independent World exists outside us, and within this Mind-Independent World are objects in space, but we only know that there are objects as a generality, we don't know what these objects are in particular

B279 – Here it had to be proved only that inner experience in general is possible only through outer experience in general.

We may know in general that Things in Themselves exist in a Mind-Independent World, otherwise we couldn't be discussing them, but that does not mean we can know individual Things in Themselves.

We may know the book in front of me in my Empirical Word, but we cannot know if there is a Book in a Mind-Independent World, as that would be a Thing in Itself.

Meaning of "Empirical World"

Does the Empirical World exist within Appearances or does it exist the other side of these Appearances, whatever is causing these Appearances?

There are different "Worlds". One exists within the mind and the other exists outside the mind, independent of the mind.

There are two meanings of the word "empirical", i) a person's subjective experience and ii) exterior, objective data (Psychology Today – Gregg Henriques)

"Empirical Realism" is a term coined by Kant in the CPR. On the one hand "Empirical" because it gives the mind an active role in the cognition of empirical objects, an aspect of epistemology in establishing a subjective empirical reality. On the other hand, "Realism", endorsing the view that there is a world that exists outside and independent of the human mind. (Paul Abela Empirical Realism).

In his Theorem for the Refutation of Idealism in B276, Kant argues that objects exist in space outside the mind

The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me.

The IEP article Immanuel Kant: Metaphysics differentiates between an "Empirical World" in the mind and a "Mind-independent World" outside the mind

Kant responded to his predecessors by arguing against the Empiricists that the mind is not a blank slate that is written upon by the empirical world, and by rejecting the Rationalists’ notion that pure, a priori knowledge of a mind-independent world was possible. Reason itself is structured with forms of experience and categories that give a phenomenal and logical structure to any possible object of empirical experience. These categories cannot be circumvented to get at a mind-independent world, but they are necessary for experience of spatio-temporal objects with their causal behaviour and logical properties. These two theses constitute Kant’s famous transcendental idealism and empirical realism.

In summary, there is an "Empirical World" inside the mind, within Phenomena, within Appearances, within the Sensibilities and within the Senses and there is also a "Mind-independent World" outside the mind.

There are different interpretations on this point. — Corvus

Kant wrote that we cannot have knowledge of a Thing in Itself. From Wikipedia Thing-in-itself

And we indeed, rightly considering objects of sense as mere appearances, confess thereby that they are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, viz., the way in which our senses are affected by this unknown something.— Prolegomena, § 32

Do you have a reference that says that Kant believes that it is possible to have knowledge of Things in Themselves?
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Things-in-themselves are for the objects we have concepts, but not the matching physical objects in the empirical world. We can think about it via concepts, but we don't see them in the phenomena. They belong to Thing-in-itself. — Corvus

You are referring to (negative) noumena, not Things in Themselves.
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If you believe in the existence of invisible particles and forces in space and time, then why do you deny the existence of the physical objects such as the bent stick in the empirical world?
If you had a single particle of the bent stick, would you say that is a part of the bent stick, and it is a stick?
In the absence of humans, sounds a condition that you must clarify before progressing further.
Where does "if something cannot be judged" come from? — Corvus

The discussion goes back to the question of whether, when we perceive a stick in our sensibilities, are we also perceiving the same object external to us in the world. This is something that the Direct Realist would argue is the case. Kant's position is not that of the Direct Realist.

You are still seeing an object external to you when you see the bend stick in the water jug. — Corvus

Do objects such as "sticks" exist in the empirical world?

In the empirical world are simples.

In the presence of humans, humans may name one particular set of simples "stick". This creates the object "stick", meaning that objects such as "sticks" do exist in the empirical world, but they only begin to exist after being named.

In the absence of humans, as naming is not possible, objects such as "sticks" cannot be created, meaning that objects such as "sticks" cannot exist.

I understand Kant's Thing-in-itself, is not everything outside us in the world. If that was the case, Kant would be an extreme sceptic, who professes everything outside us is unknowable. That would render all our knowledge of external world impossible. In that case, Kant would have been rejected for being an extreme scpetic, and nobody would take him as a serious epistemologist or philosopher. To even suggest that would be a gross misunderstanding of Kant and his philosophy. — Corvus

On the one hand, Kant held that we can never know about Things in Themselves, we can never have knowledge of Things in Themselves. Things in Themselves include everything outside us in the world, meaning that there are not some Things in Themselves that we do have knowledge of whilst there are other Things in Themselves that we cannot have knowledge of.

In philosophy, scepticism is the theory that certain knowledge is impossible.

On the other hand, I agree that Kant was not a sceptic.

To explain why Kant was not a sceptic is the subject of many articles

As a start, the fact that we cannot have knowledge about Things in Themselves does not presuppose that we cannot have knowledge about the world.
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Isn't your perception of the sticks enough evidence they exist? — Corvus

Yes, my perception of a stick is evidence that it exists – evidence that it exists in my mind.

In the same way, my perception of pain is evidence that it exists – in my mind.
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Even when no humans exist, all the material things must exist as they have been...............................Where humans don't exist, of course, there is no perception, no thoughts. But we can still make logical inference (from the human world), that things keep exist as they have done. — Corvus

My belief is in Neutral Monism, in that what exists in the absence of humans are fundamental particles and fundamental forces in space and time.

If the fundamental particles are thought of as "material things", then I agree that "material things" exist in the absence of humans.

However, I don't agree that "sticks" if thought of as a material thing exists in the absence of humans. I agree that a human can judge whether or not something is a "stick", but in the absence of humans, who or what judges that something is or is not a "stick"?

And if something cannot be judged to be either a stick or a branch, then how is it possible to be either a stick or a branch?

What Kant would have said is, that even if your sensibility sees a bent stick in the water jug, your category of concepts and understanding (followed by reading the scientific explanation on why the stick looks bent), would come to a proper reasoning on the experience, and judge the stick is straight in actuality, even if it looks bent. — Corvus

For Kant, a stick in the world outside us is a Thing-in-Itself and therefore unknowable. Being unknowable, it is impossible to judge whether bent or straight.

From the Wikipedia article on Thing-in-Itself.

In his doctrine of transcendental idealism, Kant argued the sum of all objects, the empirical world, is a complex of appearances whose existence and connection occur only in our representations.

Kant introduces the thing-in-itself as follows: And we indeed, rightly considering objects of sense as mere appearances, confess thereby that they are based upon a thing in itself, though we know not this thing as it is in itself, but only know its appearances, viz., the way in which our senses are affected by this unknown something.  Prolegomena, § 32

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What you have been calling as your internal world is nothing more than a figment of representation of the world in your mind via your sensibility from the external world. — Corvus

:100:
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What else do you need for proof that bent sticks exist in the world? — Corvus

First it has to be proved that sticks exist in the world.

There is the world inside the mind and there is the world outside the mind. The word "world" refers to two very different things

We know "sticks" exist in the mind as concepts, as we are discussing them

The question is, do "sticks" exist outside the mind and independently of any mind

Humans can judge when something is a stick and when something is no longer a stick, but in the absence of humans, in the absence of any definition of stick, in the absence of anyone to judge when something is a stick or no longer a stick, what determines when something in the world outside us is a stick or no longer a stick. A god or nature itself?

How can you prove that "sticks" exist in the absence of human thought without using human thought?

By virtue of drawing meaningful correlations between different things, some of which are not "internal to your mind". — creativesoul

There is a world outside the mind, and there is a world inside the mind, of streets with cars and building. The same word "world" is being used to refer to two very different things. The world inside the mind can only be a representation of the world outside the mind.

Kant in his Realism believed that there is a world outside the senses, and information from this world can only get into the mind through the senses, meaning that our only knowledge about an outside world comes through our senses.

The problem is, how can we correlate our thoughts about an outside world with the outside world, when we only know about an outside world by what has been given to us by our senses.

Our knowledge of an outside world stops at our senses. We may perceive the colour red through our senses, but it doesn't necessarily follow that the colour red actually exists in an outside world.

It is like saying that you used your camera, and took a photo of the mountain across the field in your town, and then the camera thinks that it has a mountain in its memory card, because it cannot understand why the mountain is out there outside the camera. — Corvus

A mountain could weigh a billion tonnes, so it is hardly surprising that the camera doesn't think it has a mountain in its memory card.

Even people only have a representation of a mountain in the minds, not the real thing. That really would be a load on their mind.

If X doesn't exist outside of RussellA, then X must exist inside of RussellA.
This sounds logically unsound. Groundless premise, and unsound conclusion. — Corvus

True. There is no reason to think that if something doesn't exist outside me then it must exist inside me.
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If X doesn't exist outside of RA? Under what ground do you claim that premise? — Corvus

An expression starting with "if" is not a premise. The expressions "X does exist outside me" or "X doesn't exist outside me" have the form of a premise.
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What do you mean by "X exist"? — Corvus

I see a bent stick. Seeing a bent stick is not proof that bent sticks exist in the world. The bent stick exists as an object in appearance whether or not a bent stick exists as an object in the world.

Similarly, I may see two things. Seeing two things is not proof that there are two things existing in the world.

Similarly, I may see a statue. Seeing a statue is not proof that there is a statue existing in the world.

Kant proposed that we have pure concepts of understanding prior to any possible experience. It would follow that it is the a priori Categories acting on the sensibilities that determine what we experience rather than our sensibilities alone determining what we experience.

For Kant, the experience of seeing a bent stick, the number two or a statue has been determined by the a priori categories acting on the sensibilities rather than by the sensibilities alone.

You have a mental space which is total darkness without your visual perception — Corvus

The light reflected from the stick in the water, passes through the water with the refraction, so it looks like double or bent in the water of the jug. — Corvus

For Kant, the pure intuition of space and time and the pure concepts of the understanding provide the possibility of experience, they don't provide the experience. As you say "You have a mental space which is total darkness without your visual perception".

For example, I may have the innate ability to perceive the colour red, but I cannot imagine the colour red in the absence of any faculty of sensibility, ie, the faculty of getting information through our senses about the world outside us.

You are correct to say that the stick that looks bent does not exist in any world outside me, but as I see a bent stick as clear as day, this means that if the bent stick doesn't exist in any world outside me, it must exist as a representation of a world that only exists inside me.

I agree that I cannot imagine any internal world in the absence of any faculty of sensibility, but because I do have the faculty of sensibility and do get information through my senses about the world outside me, the world I perceive is not directly of any world outside me but is a representation of any world outside me.

As the world I perceive is only a representation of any world outside me, the world I perceive is an internal world that is not necessarily the same as any world outside me.

I agree we cannot imagine a world in the absence of our faculty of sensibility. However, when we do perceive a world because of our faculty of sensibility, as it can only be a representation of any world outside us, the world we perceive cannot be directly of any world outside us, but can only be an internal world that is a representation of any world outside us.

They are external. You can think about it, because you have the concepts in your mind. — Corvus

Yes, this is what Kant is saying, that the pure concepts of understanding is a prior condition for experience.

IE, without these pure concepts of understanding I wouldn't be able to have the experience at all. For example, humans don't have a concept for the colour infrared as they don't have the innate ability to see infrared in the first place.

The street we see in our senses cannot be external to our senses, because the empirical concept of street is no more than the combination of pure concepts that are prior to any experience, and it is these pure concepts that determine the empirical concept of street, rather than anything external to the senses.
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How do you know your pain is real? What if it were just itchy skin, and you might have mistaken the itch sensation for pain? — Corvus

True, I may have misnamed my private sensation.

However, assuming I have correctly named my private sensation, my private sensation is real, even though it only exists in my mind.
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Close your both eyes totally and decidedly for 10 minutes, you will see nothing, but a total darkness. — Corvus

I agree that there must be something the other side of our senses, something that causes the sensations in our senses, because as you say, otherwise "we would see nothing".

I agree that we have the concept of street in our minds, because as you say "You can think about it, because you have the concepts in your mind."

The question is, what exactly is on the other side of our senses.

The Neutral Monist argues that on the other side of our senses there are no streets but only fundamental particles and fundamental forces in space and time.

The Direct Realist argues that on the other side of our senses are streets, cars and buildings.

What reasons are there to believe that the Direct Realist is right and the Neutral Monist wrong?

Just because you have a concept of something in your senses does not mean that the something you have a concept of exists on the other side of your senses. For example, when you see a stick bent in water, are you saying that on the other side of your senses there must be a bent stick in water?

How do you know you have a world internal to your mind? — Corvus

When you look at a world containing a street with cars and buildings, if this world was not internal to your mind, how would you be able to think about it?
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Is it a real world? — Corvus

Pain is real yet only exists in the mind, so why cannot your thought of a street with cars and buildings be real even though the thought only exists in your mind?
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How do you know it is the real world or just a imagination? — Corvus

Exactly, how do you know whether the street with cars and building only exists as a thought in your mind or exists outside the mind, when you only know about it through the senses?

Possible worlds, and worlds in your imagination and memories exist in your mind, but they don't cause your perception for the external world. — Corvus

How can you step outside of your concept or intuition? — Corvus

But that is what Kant is saying in the CPR, that the a priori intuitions of space and time and a priori pure concepts of the Understanding, ie the Categories, are conditions for the possibility of experience. Kant is saying that we cannot "step outside of your concept or intuition".

We perceive a world through our senses. You are assuming that there is one world in your mind and a different word that is external to your mind.

How do you know that the world you perceive in your senses has been caused by the world external to your mind rather than the world internal to your mind?

For example, when you perceive in your senses the colour red in the world, how do you know that the colour red exists in a world external to your mind rather than in the world internal to your mind?

Can you justify, for example, that the colour red exists in a world independent of any mind?
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Kant's first premise in the refutation is that he is conscious in time. Some might ask to prove how does he know he is conscious in time? What if he was dreaming, or hallucinating? — Corvus

I would agree with "I am conscious of my existence". The problem is, am I conscious of my existence at this one moment in time, or am I conscious of my existence through time.

If the latter, then I must be existing at two moments in time in order to be conscious of the passage of time. But such a possibility is beyond my powers of comprehension.

I don't think Kant's proof in the Refutation of Idealism is the best.

Surely we perceive the world via our senses doesn't necessarily mean that the world doesn't exist? — Corvus

Yes, if we perceive the world through our senses, then, of necessity, the world exists.

We perceive things in our senses, including touch, taste, smell, sight and hearing.

However, how do you know that these sensations are caused by a world that exists outside your mind rather than by a world that exists inside your mind?
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What is the reasons for George Dicker to claim that Kant's Refutation of Idealism has failed? Does it mean that Idealism prevails in CPR? — Corvus

George Dicker argues that the main difficulty with Kant's argument in B276 is the part "All time-determination presupposes something persistent in perception".

The problem is, how can we step outside of time in order to see ourselves existing in time

This doesn't mean that Idealism prevails in CPR, but rather, that Kant should have come up with a better argument to justify his belief that objects exist in space outside us.

I recall this part of CPR. It was about Refutation of Idealism. What was Kan't intention for the proof? Did he succeed in the Refutation? — Corvus

As our only access to a possible outside us is through our senses, how can we prove that there is a world on the other side of these senses when we only know of this possible world through our senses?

Not everyone believes that Kant succeeded. For example, George Dicker in his article Kant's Refutation of Idealism wrote: "I analyse Kant's Refutation of Idealism as he presents it in the Critique of Pure Reason and show that it is a failure".

His "proof" in B276 may be summarised as:
1) I am conscious of my existence though time
2) I can only be conscious of one moment in time
3) Therefore, there must be something outside me enabling my consciousness that I exist through time
However, assuming 2) to be correct, rather than being conscious of my existence through time, I could be conscious of memories at this one moment in time, thereby negating the proof.

I may be able to find justifications that there are objects outside me, but I doubt that a proof is possible. For example, if there are no objects outside me, if there is no world outside me, then I wrote "Anna Karenina", "To Kill a Mockingbird", "The Great Gatsby", "One Hundred Years of Solitude", "A Passage to India" and the "Invisible Man", which, although possible, I find highly unlikely.

What type of knowledge would it be? — Corvus

The knowledge as set out in his Theorem in B276 that objects exist in space outside us.

The "thing in itself" exists beyond the realm of human knowledge and experience. — Wayfarer

I don’t deny that Kant believed there were objects outside us. Only that we don’t know what they really are. — Wayfarer

For Kant, it was more than a belief that objects exist outside us, as from B276 onwards he goes on to propose a proof that objects do exist outside us.

On the assumption that Things in Themselves are objects outside us, then if they were beyond the realm of human knowledge, then it would not be possible to prove that they exist.

I agree that Kant may not know what Things in Themselves really are, but he does know that they do exist beyond our sensibilities.

IE, Kant proposes a proof in the Refutation of Idealism that we do have knowledge beyond our experiences.

Kant posited that human cognition is limited to what appears to us through our sensory perception and understanding. — Wayfarer

He did more than that.

In Bxxxix he writes:

"No matter how innocent idealism may be held to be as regards the essential ends of metaphysics (though in fact it is not so innocent), it always remains a scandal of philosophy and universal human reason that the existence of things outside us (from which we after all get the whole matter for our cognitions, even for our inner sense) should have to be assumed merely on faith, and that if it occurs to anyone to doubt it, we should be unable to answer him with a satisfactory proof.

From B275 onwards is Kant's Refutation of Idealism, where he states that our inner experience is only possible on the presupposition of outer experience.

He starts with the Theorem:

"The mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me."

From B276 onwards is his proof of the existence of objects outside our sensory perception and understanding.

With Kant, I'm never sure if I'm just not following it or whether it's just not followable. — Hanover

I am sure that not only is it the case that for each paragraph making a substantive point, another paragraph may be found making a contradictory point but also that for each academic’s interpretation of a particular paragraphs, another academic may be found with an opposing viewpoint.

For me, the CPR becomes worthwhile when the individual paragraphs are used in support of a sensible whole rather than trying to take each of them literally, ie, for the CPR to be read in the spirit of the text rather than in the letter of the text.
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the equation of the noumena and thing in itself — Hanover

It seems right to distinguish between two seemingly different aspects of objects as they appear in our sensibilities regardless of what they are named, whether as an abstracted generality or concrete particular, whether epistemological or ontological or whether noumena or Thing in Itself.

For me, there is a similarity between the concepts abstracted generality, epistemological and noumena and there is a similarity between the concepts concrete particular, ontological and Thing in Itself.

The analogy of the colour red

Using an analogy, we perceive the colour red when looking at a wavelength of 700nm.

The object that appears in our sensibilities, the colour red, has been caused by the wavelength of 700nm. Although the colour red and wavelength of 700nm are of two very different kinds, they are two aspects of the same event.

We can think of the colour red and the wavelength of 700nm as "the same concept viewed from two different perspectives" (Wikipedia – Noumenon)

The colour red as an object as it appears in our sensibilities can be thought of as an abstracted generality that has been determined by a concrete particular wavelength of 700nm.

The colour red as an object as it appears in our sensibilities gives us epistemological knowledge about an ontologically existing wavelength of 700nm.

For me, the colour red as an object as it appears in our sensibilities may be described as a (Negative) Noumena, and the wavelength of 700nm may be described as a Thing in Itself.

The (Negative) Noumenon and Thing in Itself are two aspects of our thoughts about objects as they appear in our sensibilities.

I agree that Kant in the CPR never discussed wavelengths of 700nm, but this does not take away the power of an analogy to explain a complex topic.

Do you understand that lies are not true and only truth is included in knowledge? — PL Olcott

Who determines that the semantic meaning of cat is "animal" rather than "very large plant-eating mammals with a prehensile trunk"?

It could be that person A stipulates that "cats are animals" and person B stipulates that "cats are very large plant-eating mammals with a prehensile trunk".

Who determines whether person A or B is correct, if the person making the determination is not allowed to look at the world using their sense data through their their sense organs?

How can there be knowledge that cats are "animals" and not "very large plant-eating mammals with a prehensile trunk" without being able to look at the world?

Only when we clarify that analytic excludes sense data from the sense organs can we know that the full meaning of a {red rose} is excluded from analytic — PL Olcott

I already said that expressions that are not elements of the body of analytical knowledge are excluded. — PL Olcott

Why can't the expression "cats are very large plant-eating mammals with a prehensile trunk" be part of the body of analytic knowledge?

It fulfils both your requirements: i) the expression excludes sense data from the sense organs and ii) being part of the body of analytical knowledge there's no reason to exclude it from the body of analytical knowledge.

I have already stipulated {the body of analytic knowledge} which necessarily excludes {cats are elephants} and includes {cats are animals}. — PL Olcott

You have stipulated the definition of cat as an animal , meaning that the expression "cats are animals" is analytic and true.

I stipulate the definition of cat as "a very large plant-eating mammal with a prehensile trunk, long curved ivory tusks, and large ears, native to Africa and southern Asia", meaning that the expression "cats are elephants" is analytic and true.

You defined analytic expressions as "Analytic expressions are expressions of language that can be verified as completely true entirely on the basis of their connection to the semantic meanings that make them true. Example: "Cats are animals"".

If by "language" you are referring to PL Olcott's private language, then your definition of analytic expressions is true.

But if by "language" you are referring to the English Language, why do you have the authority to stipulate the meanings of words in the English Language rather than me, for example? :smile:

Kingdom: Animalia...We can determine that a {cat} is an {animal} on the basis of the above knowledge tree. — PL Olcott

True, if a cat is defined as part of the Kingdom Animalia , then a cat is an animal, and the expression "cats are animals" is true and analytic.

But then, if a cat is defined as an elephant, then a cat is an elephant, and the expression "cats are elephants" is true and analytic.

The problem is that there are an infinite number of possible analytic expressions including cats. For example, "cats are animals", "cats are elephants", "cats are part of the Kingdom Monera", "cats are part of the Kingdom Protista", "cats are trees", "cats are not anmals", etc.

I accept that analytic expressions are expressions of language that can be verified as completely true entirely on the basis of their connection to the semantic meanings that make them true, and synthetic expressions are expressions of language that also require sense data from the sense organs.

If cats are defined as part of the Kingdom Animalia, then the expression "cats are animals" is analytic and true. If cats are defined as part of the Kingdom Monera, then the expression "cats are animals" is analytic and false.

In the absence of sense data from the world, the expression "cats are animals" can be either true or false.

Only by sense data from the world can the expression "cats are animals" be verified as true, meaning it a synthetic rather than analytic expression.

1) Transcendental, in Kantian philosophy, is that by which pure a priori is the determining condition.
2) From all that, it follows that a transcendental deduction, first, must be purely a priori therefore can have no empirical predication whatsoever
3) Now, with respect to a transcendental deduction of the categories, which is in fact the title of a subsection dedicated to just that, this kind of argument cannot have to do with representations of objects, because, being purely a priori, there are no phenomena hence no representations of objects, but still must be a reduction from the general to the particular in order to qualify as a deduction.
4) If Kant deduces the categories in accordance with logical syllogisms having empirical content, he loses the capacity to enounce the conditions for pure thought of possible objects.
5) A transcendental deduction can never follow from an observation, by definition. — Mww

To my understanding, these comments seem to ignore the importance of the empirical in the nature of Kant's Transcendental Deductions.

My position is along the lines of the SEP article on The Historical Controversies Surrounding Innateness

In this respect Kant agrees with Locke that there are no innate principles or ideas to be ‘found’ in us. Both hold that all our ideas have their origin in experience. But Locke thinks that we build these ideas by abstracting from experience and recombining abstracted elements. Kant holds that such representations or ideas cannot be abstracted from experience; they must be the product of careful reflection on the nature of experience.

As regards the principles and ideas that we need to make sense of experiences, Kant does not agree with the Rationalist's innatism, does not agree with Locke that we can abstract such principles and ideas just from empirical experience but does believe that such principles and ideas may be discovered from careful reflection on empirical experiences using transcendental deduction.

However, I suggest that the term "Transcendental deduction" should be treated as a figure of speech rather than literally, as transcendental requires both induction and deduction, both from the general to the particular and from the particular to the general.

From the SEP article Kant's Transcendental Arguments, a Transcendental Argument begins with a strong premise, and then reasons to a conclusion that is a necessary condition for the premise.

As I see it, the transcendental deduction of either a priori pure intuitions of space and time, a priori empirical intuitions of things such as circles or a priori pure concepts of understanding (the Categories), is not possible in the absence of an empirical experience.

I am reasonably sure that Kant's position is that it is not possible to abstract these ideas and principles just from empirical experiences, but rather, transcendentally deduce them from empirical experiences.

I am new to all this. — Debra

On the left of the screen under "Categories" is a section "Help", but is quite minimal.

1) To reply to someone, highlight a relevant part of their post, and then click on the "quote" which appears.
2) To check you are happy with your draft, click on "Preview" before clicking on "Post Comment"
3) If you want to delete your draft, at the top left of the screen, click on "Drafts", then click on waste bin.
4) Even after posting, you can edit your post. At the bottom of your post, hover the cursor over the date, then click on the three dots, which brings up edit.

More generally anything that can be encoded in language (including formal mathematical languages) <is> Analytic(Olcott). — PL Olcott

To know whether the expression "cats are animals " is analytic, one needs to know the meaning of "cats", "are" and "animals".

As an example, how is "cats" encoded in language?

Rudolf Carnap derived the basis for Richard Montague to mathematically formalize natural language. — PL Olcott

From the SEP article: Montague Semantics- the most important feature is the principle of compositionality, such that the meaning of the whole is a function of the meaning of its parts.

An example is given:

Consider the two sentences John finds a unicorn and John seeks a unicorn. These are syntactically alike (subject-verb-object), but are semantically very different. From the first sentence follows that there exists at least one unicorn, whereas the second sentence is ambiguous between the so called de dicto (or non-specific, or notional) reading which does not imply the existence of unicorns, and the de re (or specific, or objectual) reading from which existence of unicorns follows.

It seems to me that Montague Semantics is about how expressions are built out of the words used, not whether the expression is true or not. IE, as the expression "John finds a unicorn" may or may not be true, the expression "cats are animals" may or may not be true.

Montague Semantics may be able to analyse how expressions are constructed out of their parts, but not whether the expression is analytic or not.