But essentially, the amoeba eventually becomes a man. So maybe it does happen? — Pantagruel

It will happen. The more life evolves the more it will be able to understand. However, although life has been around for over 3.5 billion years, humans still have trouble using a MP3 player, so I don't hold out much hope.

So it is "mechanically" possible that there are exactly such unregistered events as Corvus is postulating. — Pantagruel

There are two aspects, being able to perceive something and then being able to make sense of it. Even if a human showed a cat a page from the book "The Old Man and the Sea", it could never make sense of it. Similarly, even if a super-intelligent alien showed us a page from "The True Nature of Reality", we could never make sense of it.

the engineer would sometimes say, all metaphysical knowledge is invalid, because it deals with things that we cannot see or touch — Corvus

Harsh on engineers. The engineer wouldn't say that the physicists knowledge of string theory was invalid because we cannot see or touch one-dimensional objects called strings.

human perception cannot catch every properties of perceptual objects in one single sense data — Corvus

Yes, as regards the apple in front of me, I am unable to perceive the quarks that make it up.

On the next perception, the unperceived properties of the objects might be perceived, and the thing-in-itself gets clearer in its nature. — Corvus

Yes, we now have photographs of individual atoms.

Some thing-in-itself objects are not likely ever to be perceived at all, but we can still feel, intuit or reason about them such as God, human soul and the universe. — Corvus

I don't agree. There is as much a chance of humans being able to feel, intuit or reason about some things-in-themselves as a cat will ever be able to feel, intuit or reason about Western Literature.

As a cat cannot transcend the physical limitations of its brain, neither can a human.

Human brain and microchip cannot compare in complexity and also capacity. Same goes with the human mind and computer software. — Corvus

True, but the principles each operates under may be the same. Gravity can attract a ball to the ground and can attract Galaxies together. A difference in complexity but the same principle applies.

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Philosophy can be done in a dark room in vacuum I believe.  You go into the room, put on a light, shut the door, take out some of your favorite philosophy books, do some reading, meditating, reasoning, and write what you think about them. — Corvus

True, as long as they have something to think about.

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The most compelling point for Kant's TI are still, whether
1. Metaphysics is possible as a legitimate science or is it just an invalid form of knowledge. — Corvus

A Metaphysician asks "what are numbers". An engineer asks "what does 130 plus 765 add up to". The engineer in designing a bridge doesn't need to know the metaphysical meaning of numbers.

Though different, both the metaphysician's question and the engineer's question are valid, both are legitimate and both are forms of knowledge.

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2. Whether Thing-in-Itself is a true independent existence on its own separate from human cognition therefore unknowable, or whether it is part of human perception, which is possible to be known even if it may look unknowable at first. — Corvus

We as humans know that for every other animal in the world there are some things that are unknown and unknowable to them because of the physical limitations of their brains. For example, we know that a cat can never understand the literary nature of Hemingway's novels.

It would hardly be surprising that as we are also animals, there are some things that are unknown and unknowable to us also because of the physical limitations of our brains.

Determinism is not the sort of thing that acts logically any more than Indeterminism...One may logically decide to step out in front of a train. — creativesoul

When we act, is it from Free Will or Determinism. It has been said that we can act illogically because of our free will, inferring that somehow Determinism is logical. This raises the question of what is logic, the subject of numerous Threads, such as the recent thread What is Logic?

My definition of logic is that is that of repeatability, in that given a prior state of affairs A then the subsequent state of affairs B will always happen. It would then be illogical for someone to say that given a prior state of affairs A, then the subsequent state of affairs may or may not be B. Repeatability must be the foundation of logic

For me, Determinism is an exemplar of logic, in that given a prior state of affairs A then the subsequent state of affairs B will always happen.

I'd say the image on the screen like any photo or painting is really a "flat" three-dimensional image — Janus

We could throw caution to the wind and call a "flat" three-dimensional image a two-dimensional image. :smile:

And, I am pointing out that this type of behaviour, where one acts contrary to one's own logical process, is explained by the concept of free will. — Metaphysician Undercover

Yes, in practice people commonly act illogically. — Metaphysician Undercover

Free Will may be an illusion

Suppose I saw someone act in an unexpected way. For example, they had bought a winning lottery ticket and then proceeded to tear it up. As an outsider, how can I know their inner logical processes in order to say they are exhibiting either Determinism or Free will.

On the other hand, if I had bought a winning lottery ticket, and freely decided to tear it up, I would think that I was exhibiting Free will. However, what if in fact my act had been determined, and what I thought was Free Will was in fact only the illusion of Free Will.

How can I know that what I think is Free Will is in fact only the illusion of Free Will?

You wouldn't call or equate a lump of computer chips and memories as mind, reason or consciousness...Of course the physical existence of the chips and memories are the body where the software defined logic and machine reasoning can be set, and happening. But they are at the software level, not hardware. Software operations are conceptual just like human mind. — Corvus

The brain can be equated with hardware and the mind can be equated with software

I would not equate a computer chip with the mind, but I would equate the computer chip with the brain.

However, there is not a clear distinction between what a thing is and what it does. There is not a clear distinction between what the brain is and what the brain does. There is not a clear distinction between the hardware within a computer and what the software the hardware enables.

A physical structure can only do what the physical structure is capable of doing. A microwave cannot play a DVD, a cat cannot debate the literary values in Ernest Hemingway's novels and the human cannot reason about things that are outwith the physical limitations of its brain.

There are forms such as the brain and hardware in a computer and there are processes, such as the mind in a sentient being and software in a computer. Form and process are distinguished by their relationship with time. The brain and hardware in a computer exists at one moment in time, but the mind and software in a computer need a duration of time in order to be expressed.

That both the mind and computer software require a duration of time to be expressed does not mean that within this duration of time either exist in some form other than physical. IE, when considering one moment in time, neither the mind nor computer software exist outside the physical form of either the brain or computer hardware. The mind and computer software are not some mysterious entities existing abstractly outside of time and space, but rather, exist as the relation between two physical forms at two different moments in time.

As you say that software operations are conceptual, we say that the mind is conceptual, But this does not mean that either the hardware of the computer or brain of the human need to exist outside of time and space in order for the software of the computer or mind of the brain to be expressed.

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Speculative philosophy can be done in a dark room full of vacuum for sure, because its tool is the concepts, logic and reasoning. — Corvus

A philosopher can only philosophise about something

A tool isn't a tool until it is used. A piece of metal at the end of a piece of wood isn't a hammer until it hammers something. As a thought must have intentionality, a thought isn't a thought until it is a thought about something. Similarly, reasoning must be about something. For example, for what reason do apples exist. Tools, concepts logic and reasoning cannot exist if they are not about something, if they don't have some object of investigation.

A Philosopher cannot work in a vacuum. A philosopher cannot philosophise if they have no topic to philosophise about, even if that topic is philosophy itself.

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Plato couldn't talk about Kant obviously, as having not been born for almost another 2000 years, Kant wasn't around when Plato was alive......................Yes, I suppose you could look at any contemporary system or thoughts under the light of Kant's TI, and draw good philosophical criticisms or new theories out of them, and that is what all classical philosophy is about. But as I said, it would be a topic of its own. — Corvus

Kant should be looked at for his philosophy not as a historical figure

True, but as we can compare and contrast Plato and Kant in order to evaluate their respective positions, we can compare and contrast Kant's Transcendental Idealism with contemporary Indirect Realism in order to evaluate their respective similarities and differences.

I think that looking at Kant as a historical figure from the viewpoint of the 18th C may be interesting as a historical exercise, but I don't think it contributes to our philosophical knowledge and understanding.

I would argue that some sort of determinism is a prerequisite for free will. We can't choose to bring about some states of affairs and not others based on our preferences unless our actions have determinant effects. We must be able to predict the consequences of our actions, to understand ourselves as determinant cause. — Count Timothy von Icarus

Yes, there is the problem of how free will can transcend what would otherwise be determined.

1) Imagine two people X and Y at time t with the same physical state of mind A.
2) Suppose person X has no free will. Suppose their physical state of mind at time t + 1 is B
3) Suppose person Y has free will. Suppose their physical state of mind at time t + 1 is C
4) The change in the physical state of mind of person X from A to B has been determined by A
5) The change in the physical state of mind of person Y from A to C cannot have been determined by A, otherwise person Y's physical state of mind would also have changed from A to B.
6) As both person X and Y at time t had the same physical state of mind A, person Y's free will must exist in addition to their physical state of mind.

If free will exists in addition to a person's physical state of mind, and determines changes in a person's physical state of mind, how is free will connected to a person's physical state of mind?

And, I am pointing out that this type of behaviour, where one acts contrary to one's own logical process, is explained by the concept of free will. — Metaphysician Undercover

I see a truck approaching me at speed.

If things were going well in my daily life, the logical thing to do would be to step to one side. This would be an example of Determinism, acting logically.

If things were going well in my daily life, even though the logical thing to do would be to step to one side, out of passion, I decide not to step to one side. This would be an example of Free Will, acting illogically.

In practice, do people act illogically? How many times do we see people in a city centre, when seeing a truck approaching them at speed, decide not to step out of the way?

If there are "forces beyond their control" these are forces not understood, because understanding them allows us to make use of them, therefore control them. — Metaphysician Undercover

The fact that gravity is a force beyond the control of humans does not mean that humans don't understand gravity.

The fact that humans understand gravity does not mean that humans can control gravity.

The difference between the physical structure which interprets, what you call the logic gate, and the human mind, is that the human mind does not necessarily have to follow the procedure when the input is applied, while the logic gate does. This is the nature of free will. — Metaphysician Undercover

You're assuming free will rather than determinism.

Why do you think humans have free will rather than being determined by forces beyond their control?

Kant never said a word about the brain in all his works as far as I am aware...Chomsky's Innatism sounds like a type of SocioBiology subject. I am sure it has nothing to do with Kant's transcendental Idealism. Neither Skinner's Behaviourism. — Corvus

True, Kant didn't talk about the brain, but then neither did Plato talk about Kant.

But surely, comparing and contrasting is an important evaluative tool in learning and developing understanding about a topic.

You compared and contrasted Kant with Plato when you wrote:
I thought about Kant as a Platonic dualist too at one point, but as @Wayfarer pointed out, there are clear differences between Kant and Plato.

You also compared and contrasted Kant with knowledge he had and knowledge that only came later, when you wrote:
Anyway, Kant was not a Phenomenologist, and Phenomenology didn't exist when Kant was alive.

I find Kant's Critique of Pure Reason relevant and interesting precisely because it can be explained in today's terms. It is not a dead historical subject, but has insights as to contemporary problems of philosophy.

Kant's Critique of Pure Reason is a battle in the war between Innatism and Behaviourism, as exemplified by Chomsky and Skinner. The a priori and the innate are two aspects of the same thing, the first from a 18th C viewpoint and the second from a 21st C viewpoint.

These we can compare and contrast.

Reason is a way our thoughts work.................Categorical items are not something that operate themselves.................... It is a rational basis for one's action and judgement......................... And of course you can talk about reason as a property of mind just like in CPR. — Corvus

:up:

it sounds like reason is some kind of a biological or living entity itself as a lump of substance. That would be Sci-Fi, not Philosophy...It is a really abstract concept. — Corvus

Where is reason exactly?

As a logic gate is a particular type of structure within a computer, I suggest that reason is also a particular structure within the brain. As the logic gate is a mechanical entity, a lump of substance, similarly, reason is a biological entity, a lump of substance.



As a logic gate has a physical existence, has a concrete existence, the logic gate cannot be said to have an abstract existence. Similarly, as reason has a physical existence, has a concrete existence, reason cannot be said to have an abstract existence .

However, I agree that the thought of a logic gate is an abstract concept, as the thought of reason is an abstract concept. This raises the question as to what are thoughts?

As a CPU within a computer interprets, processes and executes instructions, I suggest that within the brain are also particular types of structures that interpret, process and execute instructions, where a thought is no more than a difference in the physical structure of the brain between two moments in time.

However, if a thought is a difference between two things, can a difference have an ontological existence. For example, there is a difference in height between the Eiffel Tower and Empire States Building of 81metres. In what sense does this difference exist? Either differences do have an ontological existence, in which thoughts ontologically exist, or differences don't have an ontological difference, in which case thoughts don't ontologically exist.

Philosophy cannot be carried out in a vacuum, by a philosopher sitting in a dark room shut off from the world with only their thoughts. The philosopher must take the world into account within their philosophising.

As a logic gate is a mechanical entity, reason is a biological entity.

On what basis do you say we initially see a two-dimensional image? I don't, and don't recall ever, seeing a two-dimensional image. — Janus

Depends whether you are using the word "see" metaphorically or literally.

Are you not seeing a two-dimensional image on the screen of your computer/laptop/smartphone at this moment in time as you read these words?

In any event, it seems wrong to say that language would be the limit of our world. — Count Timothy von Icarus

:up:

'what two-dimensional surface do you think the purportedly two-dimensional image of our visual field is projected onto"? — Janus

When we look at the world, we initially see a two-dimensional image. I am not aware of any two-dimensional surface that this two-dimensional image is projected onto.

I looked into this further, and it seems to me Kant's Category of Cause is a concept to be applied to the external world events as cause and effect.  It is not to do with perceptions or the mental principles of reasoning. I still think the process of reasoning coming to judgements activated by intuitions, perceptions or thoughts is operated by Logic. — Corvus

I am making use of Daniel Bonevac's Video Kant's Categories.

Reason doesn't create logic, rather, what we reason has been determined by the prior logical structure of the brain

The brain must have a physical structure that is logically ordered in order to make logical sense of its experiences of the world. IE, the innate ability of the brain to process such logical functions as quantity, quality, relation and modality. In other words, Kant's Categories, aka The Pure Concepts of the Understanding.

For example, in our terms, Relation includes causality, and Quantity includes the Universal Quantifier ∀ and the Existential Quantifier ∃.

In Kant's terms, there are certain a priori synthetic principles necessary in order to make logical sense of experiences of the world . These innate a priori synthetic principles are prior to Reasoning about the phenomena of experiences through the Sensibilities. It is not the case that our reasoning is logical, rather it is the case that our reasoning has been determined by an innate a priori structure that is inherently logical, one possible consequence of the principle of Enactivism.

Our understanding of the world must be limited by what we are able to know of the world and what we can know of the world is limited by the innate structure of the brain. Taking vision as typifying the five senses, the human eye can detect wavelengths from 380 to 700 nm, which is only about 0.0035% of the total electromagnetic spectrum . In addition, understanding is also limited by the physical structure of the brain. As no amount of patient explanation by a scientist to a cat will enable the cat to understand the nature of quantum mechanics, by analogy, no amount of patient explanation by a super-intelligent alien to a human will enable the human to understand the true nature of quantum mechanics.

Kant is in effect saying that Chomsky's Innatism is a more sensible approach than Skinner's Behaviourism.

Superficially true, but insufficient to explain empirical discovery by a solitary subject. — Mww

As a solitary subject in a strange land, what would your intuition of the meaning of "ngoe" be ?

.Hume's principle of constant conjunction...............has more to do with the relation of cause and effect than to perception and cognition — Mww

From the IEP article on David Hume: Causation
Whenever we find A, we also find B, and we have a certainty that this conjunction will continue to happen.

If every time I see a particular object and hear someone say "Eiffel Tower", there is a good chance, though not absolute, that the name of this particular object is "The Eiffel Tower".

In a sense, the object does cause someone to say "The Eiffel Tower", in that there is a causal link between the object and the name.

But you just said the name is given by a relevant community, and if “tree” is that name for an object looked upon in the world by yours…..how can it be unique to you? — Mww

The Icelander and Ghanaian can agree with the Communal definition of tree as "a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at some distance from the ground".

However, each will have their own unique understanding of what trees are based on their very different lifetime experiences.

No. I knew instead what "a thought of a cup" would mean in the context of our discussion. When I think about a cup I'm doing something, but no "thought of a cup" exists. — Ciceronianus

It is only possible for you to write that "but no "thought of a cup" exists" if you already know what the thought of a cup is.

IE, I can only say that that building over there is not the Eiffel Tower if I already know what the Eiffel Tower looks like.

Similarly, you can only say that the thought of a cup doesn't exist if you already know what the thought of a cup is.

It is never the case we think with language, or by means of it. — Mww

I agree. I have a pain in my left hand whose exact nature is inexpressible in language. The fact that I cannot express in language the exact pain does not mean that there is no pain. As Wittgenstein himself wrote in PI 293 of Philosophical Investigations: "The thing in the box has no place in the language-game at all"

We think, and name that which is thought about, the object of thought, cup. — Mww

We look at the world and see an object that has been given a name by the Community within which we live.

Both the object and name are physical things that exist in the world, and we link the object and the name through Hume's principle of constant conjunction.

The name doesn't describe the object, but is linked with the object through Hume's principle of constant conjunction.

IE if every time I saw the Eiffel Tower and at the same time heard the name Eiffel Tower, I would begin associate the name Eiffel Tower with the object Eiffel Tower

As a name is only linked with a thought of an object by Hume's principle of constant conjunction, the one can exist independently of the other. IE, one can have the thought of an object independently of any name it may or may not have been given.

MANY years ago, by sheer accident I put a chainsaw into my left foot. — Mww

Many years ago, I had a garden fork go though my right foot, so I do have an idea of what you experienced.

That every single word ever, and by association every single combination of them into a whole other than the words themselves, being at the time of its instantiation a mere invention, is for that very reason entirely private? — Mww

Yes, for example what I understand by the word "tree" is unique to me, as no one else has had the same life experiences. IE, the meaning of "tree" for an Icelander can only be different to the meaning of "tree" for a Ghanaian.

It may do well to note, in addition, as long as we’re “making a case for transcendental idealism”, that since it is merely the thought “cup”, there is already the experience of that particular object by the same subject to which the thought belongs, for otherwise the subject would’ve not had the authority to represent it by name. — Mww

How can a thought be named ?

Is it the case that we have the thought of a cup and then name it, or is Wittgenstein correct
in his belief that we cannot think without language. He wrote in the Tractatus para 5.62: “the limits of my language mean the limits of my world.”

If Wittgenstein is correct, then the mere act of writing "the thought of a cup" presupposes the thought of a cup.

2. It is awkward to speak about things-in-themselves; — Bob Ross

"Awkward" in (2) was used somewhat sardonically; "impossible" would presumably be more accurate. — Banno

Wittgenstein in para 293 of Philosophical Investigations makes a strong case that we can speak about things-in-themselves.

He writes:
But suppose the word "beetle" had a use in these people's language?—If so it would not be used as the name of a thing. The thing in the box has no place in the language-game at all; not even as a something: for the box might even be empty.—No, one can 'divide through' by the thing in the box; it cancels out, whatever it is. That is to say: if we construe the grammar of the expression of sensation on the model of 'object and designation' the object drops out of consideration as irrelevant.

A word such as "red" does not describe a thing-in-itself, but replaces the thing-in-itself, allowing us to sensibly talk about things-in-themselves.

IE, in Wittgenstein's terms, there is an equivalence between the words "red", as in "I see a red post-box", and "beetle".

Have you managed to find Sense and Sensibilia? — Banno

Thanks, I have downloaded a copy and will read it. :up:

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You don't see the cup as having depth? Odd. — Banno

Are you using the word "see" metaphorically?

In my field of vision, I can only see the surface of any object facing me, which appears two-dimensional, but in my mind I can imagine the three-dimensional space the object occupies.

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It's a very odd thing for RussellA to say - even folk with one eye have depth perception. — Banno

I didn't actually say that, but even if I had, I would be in good company.

The BBC Science Focus notes that:
For example, we know the size of things from memory, so if an object looks smaller than expected we know it’s further away.

The atom used to be the stand-in for 'simple' in that it was 'indivisible', not composed of parts. Regrettably, nature did not oblige, as it turns out atoms are far from simple. — Wayfarer

:up:

Are you not familiar with the depth perception due to parallax? Is there really any such things as a two-dimensional image? Even lines and the paper they are on are really three-dimensional. — Janus

Parallax can be used to determine the distance of an object, as nearby objects show a larger parallax than farther objects, but it doesn't allow us to see the back of a three-dimensional object.

What is parallax doing? Is it giving us information about the distance of an object from us or is it giving us information about the three-dimensional space that the object occupies?

Sorry, but I don't think there is such a thing as a "thought of a cup." — Ciceronianus

In order to write the sentence "Sorry, but I don't think there is such a thing as a "thought of a cup."" you must have had the thought of a cup.

I am still saying that, just the red patch colour visual perception would be more meaningful than the scientific instrument reading of the red patch emission of 700nm to the most ordinary people — Corvus

Yes, as you say, most ordinary people can understand Naïve Realism.

Even if the supposed Atom images are seen in the microscope, how do you know they are atoms? — Corvus

Yes, even the atom is a representation of something deeper, which is why my position is that of Indirect Realism. As the IEP article on Objects of Perception writes:
The indirect realist agrees that the coffee cup exists independently of me. However, through perception I do not directly engage with this cup; there is a perceptual intermediary that comes between it and me. Ordinarily I see myself via an image in a mirror, or a football match via an image on the TV screen. The indirect realist claim is that all perception is mediated in something like this way. When looking at an everyday object it is not that object that we directly see, but rather, a perceptual intermediary. This intermediary has been given various names, depending on the particular version of indirect realism in question, including “sense datum, ” “sensum,” “idea,” “sensibilium,” “percept” and “appearance.”

I think that what you call Indirect and Direct Realism reflect a pseudo-problem.........................We see a cup made up of atoms, then. Does that make it any less a cup? — Ciceronianus

As Bertrand Russell in The Problems of Philosophy wrote:"But the notion of being 'in' the mind is ambiguous. We speak of bearing a person in mind, not meaning that the person is in our minds, but that a thought of him is in our minds."

In the expression "we see a cup made up of atoms", the underlying problem is the inherent ambiguities within language. It is not a cup that is the object of consciousness, but rather the thought of a cup that is the object of consciousness. There is no cup in our minds, only the thought of a cup.

There is the act of apprehending a cup in a mind-independent world, but this does not mean that there is a cup in a mind-independent world that is being apprehended.

The question as to whether cups exist or not in a mind-independent world is certainly not a pseudo-problem, as it is crucial to our understanding of the nature of reality.

Strictly speaking, wouldn't it be the instruments (invented and calibrated for their own convenience by humans) which tells the wave length of 700nm emission, rather than science? — Corvus

Difficult to escape from a metaphorical use of language. I am using "science" is a figure of speech that includes the instruments of science.

See, could be, not necessarily or for definite. "could be" sounds a negativity in disguise here — Corvus

Wholes have parts, which in turn have parts, which in turn have parts. But sooner or later one assumes there are parts which have no parts, ie, simples. In contemporary mereology, a simple is any thing that has no proper parts. Sometimes the term "atom" is used, although in recent years the term "simple" has become the standard.(Wikipedia - Simple (philosophy)). It may be that fundamental forces and fundamental particles are simples, but science may discover it to be something else altogether.

Not sure, if science has to be consulted for that assurance. Wouldn't common sense or intuition do? And we don't really care about a set of atoms unless for some peculiar reason. To me atoms are just an abstract concept, that doesn't exist in the real world. Or if it did, it has nothing to do with me, or daily life. — Corvus

Science can tell us things that intuition cannot, such as when we perceive a red object, such as a post-box, the object may have emitted a wavelength of 700nm.

I only mentioned science to try to distinguish between a subjective mind and objective world. Coming from a position of mereological nihilism, my belief is that the cup as appearance does exist in the mind but the cup as thing-in-itself doesn't exist in a world independent of any mind.

In a sense, "atoms" are a convenient figure of speech for mereological simples, whatever they may be, but could be fundamental forces and fundamental particles existing in time and space.

So you might say Kant says that there are two cups?  That is absurd...............Logic is the engine of how rationality, intuition, perception, understanding and judgement works. — Corvus

When I look at a cup, in my mind is a two-dimensional appearance, but science tells me that what I am actually looking at is a set of atoms in a three-dimensional space.

In one sense there are two cups, the cup as it exists as a two-dimensional appearance in my mind and the cup as it exists as a three-dimensional set of atoms, both of which are very different. But in another sense, there is only one cup, the cup as a thing-in-itself in the world as the cause of the cup as an appearance in my mind.

What is crucial is a logical connection between the thing-in-itself in the world and the appearance in the mind, and this connection is what Kant understands as the Category of Cause. Kant's Category of Cause is what ensures that there is only one cup, even though the cup may exist in different forms, first as a set of atoms in three dimensional space in the world and then as a two-dimensional appearance in the mind.

Kant's Category of Cause is crucial to the viability of his Transcendental Idealism.

But when we talk about the cup, the pot, the cupboard, we are not talking about our private perception-of-cupboard, or the pot in itself, or one's mental image of a cupboard, but about the cup, cupboard and pot. — Banno

Both the Indirect and Direct Realist see a red cup, take it out of the cupboard, boil the kettle and make themselves a cup of tea.

However, the Indirect Realist takes into account the fact that science has told us that the cup we perceive as red is actually emitting a wavelength of 700nm. This causes them to question whether what they perceive as a red object is actually red. They then begin to question the relation between the appearance of an object and the object as a thing-in-itself.

However, Direct Realism turns a blind eye to scientific discoveries and continues to insist that when we perceive an object to be red it is actually red.

The Direct Realist refuses to address Kant's concerns about the ontological nature of objects in the world, and limit themselves to Wittgensteinian Linguistic Idealism, whereby language games are founded on hinge propositions, such as "I see a red cup". Such hinge propositions remain true regardless of the ontological reality of the world .

Part of the problem is that whilst the Direct Realist wilfully ignores Kantian concerns with the ontological nature of reality in favour of Linguistic Idealism, the Indirect Realist is willing to take into account not only Kant's ontological concerns but also Wittgenstein's Linguistic Idealism, acknowledging that language is needed to talk about the non-linguistic.

I think this is a question only if we assume that we or our "minds" are separate from (outside) of the world. That's not an assumption I think we should make. We are a part of the world, not outside it. The chair is a part of the world as well. The chair isn't part of us. We aren't a part of the chair. We are a part of the world. The world isn't inside us, as we're a part of it. We have certain characteristics as human beings. We interact with the world as human beings do. We see as human beings do, hear as they do, etc. There's nothing surprising about this, and it doesn't establish in itself that we can't know what it is we encounter or interact with. — Ciceronianus

As an Indirect Realist, I agree with your paragraph, as would a Direct Realist, but this does not address the topic of the thread "A Case for Transcendental Idealism". In other words, "A case for Indirect Realism".

Both an Indirect and Direct Realist would agree that both us and the chair are part of the same world, but they would disagree as to the nature of this world

You inferred before your support for Direct Realism as opposed to Indirect Realism
To Kant, though, is reserved the claim that there is, e.g., some thing which I call a chair and sit on all the time, which although it is in all respects a chair as I understand a chair to be and I use it as such, cannot be known.

I am persuaded by Bertrand Russell's support for Indirect Realism as he sets it out in the beginning of his book "The Problems of Philosophy"

My question is, how does the Direct Realist answer Indirect Realism's objections to Direct Realism?

. And, if we can't know what "things in themselves" really are, what possible difference would it make? — Ciceronianus

This morning, when making a cup of tea, it didn't pass my mind whether the cup was an appearance or a thing-in-itself. But this is a Philosophy Forum, where such considerations are of interest.

Neither you nor I have minds lurking within us, separate from the rest of us. We think as part of our interaction with the rest of the world. Language as well is a result of that interaction, as are the definitions arrived at in the use of language. — Ciceronianus

I believe in Enactivism, the philosophy of mind that emphasizes the interactions between mind, body, and the environment (Wikipedia - Enactivism). I agree with Dewey's cultural naturalism, where philosophy should be seen as an activity undertaken by inter-dependent organisms-in-environments (SEP - John Dewey)

We agree that we as humans interact with the rest of the world, but the central question remains unanswered, where exactly is this world that we interact with?

For example, this question was never addressed by Wittgenstein in Philosophical Investigations.

There is certainly a world that we interact with, but is this the world of the Direct or Indirect Realist.

Is it the case as the Direct Realist believes that the world as we perceive it exists independently of our perception of it but exactly as we perceive it, or is it the case as the Indirect Realist believes that the world as we perceive it only exists as a representation of something that exists outside our perception of it.

Yes, there is a chair in the world that we interact with, but does this world of chairs exist in our minds or outside our minds?

It's strange to think of the phenomena/noumena distiction in relation to one's own body parts. Is there a nose-in-itself vs the phenomena of it? — Gregory

After an amputation, some people experience pain in the part of the limb that’s no longer there. This sensation is phantom limb pain. The pain is real. The phantom part refers to the location of the pain: the missing limb or part of the limb (such as fingers or toes) (Leveland Clinic - Phantom Limb Pain)

Moore famously put the point into dramatic relief with his 1939 essay Proof of an External World, in which he gave a common sense argument against scepticism by raising his right hand and saying "here is one hand," and then raising his left and saying "and here is another" (Wikipedia - Here is one hand)

Who is to say that Moore hadn't had both his hands amputated after an accident, and only imagined his hands were still there?

Here's a small chance, a chink in the wall of Kant*. What if talk of the cup perceived and of the cup's ding an sich are talk of the very same thing? Perhaps there is just one cup? — Banno

Given your position as a Direct Realist, and assuming Direct Realism, when we look at an object and perceive the colour red, science may tell us that the object has emitted a wavelength of 700nm

How can the Direct Realist justify that a perception of red in the mind and a wavelength of 700nm in the world are the very same thing?

To my understanding Kant became a dualist because of the arguments by Hume that physical "laws" cant be known — Gregory

Yes, empirical knowledge is insufficient by itself for understanding. In today's terms, Innatism is also needed.

Also i'd like to say that if a positivist says he is not an idealist, why won't he just call himself a materialist then? — Gregory

If Positivism is the philosophical theory that holds that the only true knowledge is scientific knowledge, based on data and experience, then Kant was not a Positivist.

I would say there is no "thing" called a concept floating about in a thing called a "mind." — Ciceronianus

We both have the concept of a "thing" in our minds. If our concept of "thing" doesn't exist in our minds, then where does it exist?

Concepts and minds all exist in the same world as chairs — Ciceronianus

It seems that your position is that of Idealism.

First, you have inferred that the chair can be known:
To Kant, though, is reserved the claim that there is, e.g., some thing which I call a chair and sit on all the time, which although it is in all respects a chair as I understand a chair to be and I use it as such, cannot be known

Also, you have said that minds exist in the same world as chairs:
Concepts and minds all exist in the same world as chairs.

Kant was a philosophical Realist. From the Wikipedia article Philosophical Realism
Philosophical realism – usually not treated as a position of its own but as a stance towards other subject matters – is the view that a certain kind of thing (ranging widely from abstract objects like numbers to moral statements to the physical world itself) has mind-independent existence, i.e. that it exists even in the absence of any mind perceiving it or that its existence is not just a mere appearance in the eye of the beholder

From the Wikipedia article on Idealism
Idealism in philosophy, also known as philosophical idealism or metaphysical idealism, is the set of metaphysical perspectives asserting that, most fundamentally, reality is equivalent to mind, spirit, or consciousness; that reality is entirely a mental construct; or that ideas are the highest form of reality or have the greatest claim to being considered "real"

To Kant, though, is reserved the claim that there is, e.g., some thing which I call a chair and sit on all the time, which although it is in all respects a chair as I understand a chair to be and I use it as such, cannot be known. — Ciceronianus

We all have the concept of a chair in our minds, and we only know what a chair is because in our minds is the concept of a chair.

It is true that you can point to something in the world that corresponds with your concept of a chair, but you cannot point to something in the world that is your concept of a chair. IE, concepts exist in the mind, not in a world outside the mind.

Kant is not saying that we have no concept of chair in our minds, but he is saying, as would an Indirect Realist, that concepts only exist in the mind and not in a world outside the mind.

@Bob Ross @J

For every effect there is a cause
We know that one of Kant's Categories was the Category of Cause. There are many passages in the Fourth Paralogism, where the thing-in-itself is declared to be the cause of appearances. For Kant, Knowledge is both formal, a priori through the Category of Cause, and material, a posteriori given empirically through sensations.

I agree with @J who wrote "surely Kant didn't "deny that things exist outside the mind" -- he merely sought to discover the limits of our knowledge of them".

Common sense tells us for every effect there has been a prior cause. EG, a snooker ball on a snooker table doesn't spontaneously move until hit by either a snooker cue or another snooker ball.

Reason tells us that the same effect may have different causes, eg, a broken window could have been caused by either a ball or a bird. Reason also tells us that two different effects have two different causes, eg, perceiving the colour red may be caused by an object emitting a wavelength of 700nm and perceiving the colour green may be caused by an object emitting a wavelength of 530nm.

The perception of the colour of objects in the world
Science tells us if an object emits a wavelength between 620nm and 750nm, all things being equal, we perceive the colour red, and if an object emits a wavelength of between 495nm and 570nm, all things being equal, we perceive the colour green.

For the Indirect Realist, the effect, eg, the perception of the colour red, can have a different kind of existence to its cause, eg, an object emitting a wavelength of 700nm. For the Direct Realist, the effect, eg, the perception of the colour red, has the same kind of existence as its cause, eg, an object emitting the colour red.

For the Indirect Realist, in the absence of any observer, an object emits a wavelength of 700nm. For the Direct Realist, in the absence of any observer, an object emits the colour red.

Does colour exist outside a person's perception of it
When we look at one object emitting a wavelength of 640nm and another object emitting a wavelength of 730nm, all things being equal, we perceive that they are similar in some way, ie, both red. But when we look at one object emitting a wavelength of 640nm and another object emitting a wavelength of 530nm, we perceive that they are different in some way, ie, one is red and the other is green.

The Indirect Realist attributes this to how the wavelengths are perceived in the mind.

Question to Direct Realists
My question to the Direct Realist is, in the absence of anyone perceiving such objects, whilst agreeing that the wavelengths of 640nm and 530nm are different, in what way is it possible for the wavelengths of 640nm and 730nm to be similar?