Also, with an essay it seems that there is a need to come up with an independent view. — Jack Cummins

As I see it:

A philosophy essay is a specific thing and is not the same thing as a literary essay. This is a "Philosophy writing challenge". In a philosophy essay, one starts with a thesis about which one makes a claim and then defends it.

In fact, it is not even necessary to believe the claim that you are making, as long as you make a strong argument for it.

For example, the thesis could be "The public are better off under an Oligarchy than a Democracy" You could either defend this claim, oppose this claim or claim that sometimes Oligarchies are better than Democracies. Whichever claim you are making, you need to support your claim with a strong argument.

Perhaps a philosophy essay is more about your reasoned defence of your claim than the actual topic itself.

As regards independent view, I am assuming that an essay of say 2,000 words at undergraduate level will be more suitable than a PhD Dissertation of say 100,000 words. This affects what is meant by "independent view".

In an undergraduate philosophy essay, the writer is not expected to independently develop a new philosophical idea, but is expected to show independence of thinking in reasoning about existing philosophical ideas.

There is a difference between having a view that is independent of current philosophical ideas and having an independent view about current philosophical ideas.

For example:
1) You could begin with a declarative statement expressing your opinion "The public are better off under an Oligarchy than a Democracy"
2) Then i) give the main evidence that supports your claim and ii) your reasons why this evidence supports your claim.
3) Then give one or two main counter-arguments
4) Then give reasons why you rebut these counter-arguments
5) Finish by summarising your reasons why the evidence supports your claim and your reasons for rebutting the counter-arguments.

As an exercise in writing a philosophy essay, you could defend a claim that you don't even believe in, as long as you made a persuasive case.

I don't understand how we could replace 1 by 3. — frank

If there is one object in the world, dividing it into three parts does not involve infinities. In our numbering system, dividing 1 by 3 does involve infinities.

This suggests that infinity is an artificial problem of our numbering system. Perhaps a different numbering system would avoid the problem of infinity altogether.

Could you describe what mind-independent world could be? — Corvus

Impossible for the mind to describe a mind-independent world.

What do we do with numbers like pi that go on forever? — frank

One third of 1 is 0.33333...........continuing to infinity.

If we altered our numbering system, such that we replaced 1 by 3, then one third of 3 is 1. This avoids any problem of infinity.

This suggests that the problem of infinity is an artificial problem of our numbering system.

Similarly with pi.

They are subjective mental states, nothing to do with knowledge. — Corvus

Our only knowledge about any mind-independent world, any objective reality, starts with our subjective mental states. This means that knowledge about an objective reality cannot be separated from our subjective mental states.

When there is discrepancies in the claims of knowledge on the same situation or object between different folks, you always have chance to carry out testimonies on the knowledge via repeated observations, experiments, or testing on the claims, and update your false beliefs, or correct the other folks false claim on his knowledge. — Corvus

True, if two people make different claims about the same situation, for example, one says the postbox is red, and the other says the postbox is green, their claims can be judged.

But as regards perception, what a person perceives in their mind cannot be judged by anyone other than that person, as mind reading is impossible.

In exactly the same way, any pain a person experiences cannot be judged by anyone other than that person, as mind reading is impossible.
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What we see is the only world there is. There is no other world. — Corvus

You could only know what another person sees in their mind if you were a mind reader, which is an impossibility.

Only a mind reader could know that what another person sees in their mind is the same as what they see.

Seeing a colour and feeling a pain are both subjective experiences that are unknowable to any one other than a mind reader.
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Mind-independent world is meaningless if you cannot see or know what it is. — Corvus

If you knew something about a mind-independent world then it couldn't be a mind-independent world.

That would be like knowing something that is unknown.

We do have knowledge about the truth of reality, because we have perception and reasoning and inferring on the perception. Not just perception. — Corvus

Ideal Realism is about a relation between the mind and the world: "The universe is just ideas in the head, but real. Matters are only real when accessible and interactable. When not, all matters are just ideas."

If person A was stung by a wasp, only person A would know their particular pain. Person B may know their own particular pain when stung by a wasp, but as mind reading is not possible, it is impossible for person B to know person A's particular pain.

The top light of a traffic light is labelled "red", the middle light is labelled "orange" and the bottom light is labelled "green".

When person A sees the top light of a traffic light, only person A knows the particular colour that they see. Similarly, person B knows the particular colour that they see. As mind reading is not possible, it is impossible for person B to know the particular colour that person A sees.

Therefore person B can never know whether they are seeing the same or different colour to person A

Therefore, it is possible that persons A and B are in fact seeing different colours.

If persons A and B are seeing different colours, then either one of them or both of them are wrong about the reality of the colour of the top light.

If person B is wrong about the true nature of the traffic light, then this means that even though they see a particular colour of the top traffic light, that particular colour may not in reality be the actual colour of the top traffic light. This means that even though person B sees the colour red, the top traffic light may not in reality be red.

If person B is right about the true nature of the top traffic light, it is possible that person A is wrong.

If person A is wrong about the true nature of the top light, then this means that even though they see a particular colour of the top traffic light, that particular colour may not in reality be the actual colour of the top traffic light. Therefore, even though person A sees the colour red, the top traffic light may not in fact be red.

But persons A and B are interchangeable,

Therefore, it is possible that a person may see a colour that in fact doesn't exist in reality in the world

Direct Realism is the theory that all people directly see the colour that exists in reality in the world, but as mind reading is not possible, this is unknowable.

Therefore Direct Realism is not a valid philosophy. The reality of a mind-independent world is inaccessible to the mind.

For empirical cases like seeing colour red, you must go out and investigate further and verify for the truth, if needed. — Corvus

Suppose in reality the truth is that an object in the world is green, but for whatever reason you always perceive green objects as red.

You could look at the green object from all directions and all times of the day and will always see this green object as red.

How is it possible for the human mind to analyse the fact that they always see a red object to discover the truth of reality that the object in the world is actually green?
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Your seeing colour red is not knowledge. — Corvus

Your seeing the colour red is knowledge about what is in the mind, but is not knowledge about what is in the world.

Knowledge is justified true belief.

As regards the mind, the colour you see is the colour you see, regardless of its name. The colour you see is necessarily a justified true belief, and is therefore knowledge.

As regards the world, you may believe the colour of the object is red. You may be able to justify that the colour of the object is red. But if the object is in reality actually green, then you have no knowledge about the truth of reality.

Perception cannot give us knowledge. It can only present with what is perceived in the form of raw data i.e. shapes, colours, sounds, words and motions. That is where it ends. It is our reasoning and inference which give us knowledge on the reality. Hence both DR and IRists are wrong. — Corvus

We perceive the colour red and reason that it was caused by a red object in the world.

Knowledge is justified true belief.

Just because we have reasoned that our perception of the colour red was caused by a red object in the world, suppose we are mistaken, and in fact our perception of the colour red was not caused by a red object in the world.

Suppose it was caused by a green object. We wouldn't then have knowledge about reality in the world.

Why should our perceptions necessarily give us knowledge about the world?

Perception cannot give us knowledge. It can only present with what is perceived in the form of raw data i.e. shapes, colours, sounds, words and motions. That is where it ends. It is our reasoning and inference which give us knowledge on the reality. Hence both DR and IRists are wrong. — Corvus

It depends what is meant by "knowledge".

Knowledge could mean justified true belief. If I believe that the Eiffel Tower is 330m tall and can justify my belief, perhaps I read it in Encyclopedia Britannica, and the Eiffel Tower is actually 330m tall, then I have knowledge about the Eiffel Tower

I agree that we perceive things and can then use our reason on these perceptions in order to give us knowledge about the world, such that the Eiffel Tower is 330m tall.

But in order to reason about my perceptions, I must first know that I am perceiving the colour red, for example. I don't think that I am seeing the colour red. I don't believe that I am seeing the colour red. I don't need to reason that I am seeing the colour red. I know that I am seeing the colour red.

Is knowing something knowledge? Is knowing that I see the colour red knowledge that I see the colour red?

In propositional terms, when I say "I know the Eiffel Tower is 330m tall", the fact "the Eiffel Tower is 330m tall" is knowledge. Similarly, when I say "I know I see the colour red", the fact "I see the colour red" is knowledge.

I would say that I have knowledge that I see colours, shapes, sounds, etc

It seems that knowledge can be about what is in the mind as well as what is outside the mind.

Does it mean that Indirect Realist can only have beliefs? No knowledge at all?
And likewise, Direct Relists can only have knowledge? No beliefs at all? — Corvus

The meaning of the words "direct knowledge" and "indirect knowledge" depends on context.
In ordinary language, I have direct knowledge of The Empire States Building as I have visited it, but I only have indirect knowledge of The Space Needle as I have never been there.

In philosophy, I have direct knowledge of my perceptions of the colour grey and rectangular shape, but I only have indirect knowledge through reasoning of the something in the world that may have caused my perceptions.

The meaning of the words "knowledge" and "belief" depends on context.
In ordinary language, I know that the Eiffel Tower is in Paris, and I believe that the Eiffel Tower was built in 1889.

In philosophy, I know my perception of the colour red, and I believe that there is something in the world that caused this perception.

The Indirect Realist
Not entirely. The Indirect Realist has knowledge about what exists in their mind, such as when they perceive the colour red. But they argue that we can only have beliefs about what exists in the world that may be causing these perceptions in the mind.

The Direct Realist
The Direct Realist argues that they have knowledge about what exists in their mind, such as when they perceive the colour red, and they argue that they also have knowledge about the something in the world that caused these perceptions in the mind.

However, as I see it, Direct Realist is an invalid philosophy. IE, they are wrong.

That seems to imply that they are back to the dualism. — Corvus

Yes, but there is nothing fundamentally wrong with dualism.

If there was no dualism there would be no language. A word on the one hand exists as a shape and on the other hand exists as a representation of something else.

1) What is the significance of direct and indirect knowledge?...........................................3) What are the differences in direct and indirect knowledge compared to knowledge? — Corvus

I have direct knowledge of New York because I have been there, but only have indirect knowledge of Seattle as I have never been there.

I have direct knowledge of my perception of red, but only have indirect knowledge of the something in the world that might have caused it

Indirect knowledge signifies a belief.

I believe that the Space Needle in Seattle was originally sketched on a napkin, but I don't know it for a fact as I wasn't there at the time.
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2) Indirect or direct on relation to what? — Corvus

In relation to something in the world. The relation between what exists in the mind and what exists in the world.

That sounds confusing. Is it not the other way around? Are you sure you haven't put them wrong way around in the definition? What significance the word "indirect" have in the name? Why indirect? — Corvus

I don't believe so.

Suppose someone perceives the colour red. Both the Indirect and Direct Realist would agree that something in the world caused their perception.

The Direct Realist would argue that they are directly seeing the something in the world that caused their perception. They argue that the something in the world is actually red.

The Indirect realist argues that they are directly perceiving the colour red in their mind and only know about the something in the world that caused their perception indirectly through reason. They argue that the something in the world might be red, might be green, might be a wavelength of 700nm or might be something else altogether.

The Direct Realist argues that they have direct knowledge about the something in the world that caused their perception, whereas the Indirect Realist argues that their reasoning can only give them indirect knowledge about the something in the world that caused their perception.

So what is the difference between indirect realism and direct realism? From what you are saying, they sound exactly the same claims. — Corvus

As I wrote on page 2

Suppose someone perceives the colour red. Both the Indirect and Direct Realist would agree that something in the world caused their perception.

The Direct Realist says the person is directly perceiving the cause of their perceiving the colour red. The Indirect realist says that the person is only directly perceiving the colour red.

You seem to be confusing the point that I was trying to point out the fact that transcendental idealism has problem of having dualistic view of the world i.e. phenomenon and noumenon — Corvus

A dualistic view in itself is not necessarily incorrect. For example, a word is an example of dualism. On the one hand it exists as a shape and on the other hand it exists as what it is representing.

This describes Direct Realism:

When the perceiver and the world is in direct physical contact which allows the perceiver to have direct perception, sensation, and interaction with the world or objects in the world, the world presents to the perceiver as physical entity or material objects. — Corvus

This describes the Direct Realist closing their eyes and using their imagination:

When the perceiver is only thinking about the world without direct visual or material sensation or perception, the world is in the mind of the perceiver as ideas only. — Corvus

You haven't answered the key point question. What do you mean by "regardless of any cause"? Why is it relevant to the point? — Corvus

I wrote "When I perceive the colour red, I perceive the colour red regardless of any cause."

It goes back to your two previous statements:

You end up having 2x copies of every object in your perception, and wonder which one is the real object. — Corvus

Indirect realism's problem is using sense data as the medium of perception, which doesn't make sense. — Corvus

I am trying to show that this is a misrepresentation of Indirect Realism. For Indirect Realism, there is only "1x copy of every object in your perception."

This means that when an Indirect Realist perceives the colour red, they are only directly perceiving the colour red. They are only directly perceiving one thing. They are not directly perceiving two things, the colour red and the cause of their perception of the colour red.

As I wrote:

When the Indirect Realist perceives the colour red, for example, they are not perceiving a representation of the colour red, they are directly perceiving the colour red.
Anything otherwise would lead into the homunculus problem of infinite regression.
What the Indirect Realist does believe is that there is something in the world that has caused them to perceive the colour red, but it is unknowable whether this something in the world is actually red or not. The Indirect Realist reasons that it is not, but cannot know for sure.
In a sense, the colour red that is directly perceived is a representation of the unknown something in the world, which may or may not be the colour red.
There is only one object of perception for the Indirect Realist, and that is the direct perception of the colour red.

What are the ultimate reality for these folks in detail? — Corvus

Presumably the same as for the idealists and the materialists.

The point of idealism or materialism is to define what the ultimate reality is in the end. — Corvus

It sounds like a tautological statement, which doesn't convey any knowledge. — Corvus

The statement "When I perceive the colour red, I perceive the colour red" is a tautological statement.

The statement "When I perceive the colour red, I perceive the colour red regardless of any cause" is not a tautological statement.

Suppose someone perceives the colour red. Both the Indirect and Direct Realist would agree that something in the world caused their perception.

The Direct Realist says the person is directly perceiving the cause of their perceiving the colour red. The Indirect realist says that the person is only directly perceiving the colour red.

Saying "When I perceive the colour red, I perceive the colour red regardless of any cause" is distinguishing Indirect from Direct Realism.
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The point of idealism or materialism is to define what the ultimate reality is in the end. But IR and DR seem to just make vague statements on how they perceive via unknown causes or directly. They just end there. So what is the ultimate reality? They don't seem to be interested in it. Hence no point. — Corvus

A bold statement that neither Indirect nor Direct Realism are interested in the nature of ultimate reality.

Indirect Realism is about the limits of knowledge of ultimate reality. Direct Realists do believe that they know ultimate reality.

There would be no cases such that the cause of break is unknown in medical incidents. — Corvus

I doubt that the cause of a medical condition is always known.

Even though the broken leg has a cause, the doctor is treating the broken leg, the doctor is not treating the cause of the broken leg.

When I perceive the colour red, I perceive the colour red regardless of any cause.
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Not really. Their systems are not denied here. Rather, the OP is based on their systems, but seeing the world in a different way like Husserl and Merlou Ponty have done. — Corvus

You may not deny Indirect and Representational Realism, but you infer there is no point in them.

Doesn't sound it has a point in saying that something has cause but they don't know what the cause is. — Corvus

Doesn't sound it has a point in saying that something has cause but they don't know what the cause is. — Corvus

It would be like a doctor refusing to treat someone in pain with a broken leg until they knew the cause of the break.

It is a brave statement that there is no point in Indirect or Representational Realism, and philosophers such as Aristotle, John Locke, Immanuel Kant, Rene Descartes, Baruch Spinoza and Bertrand Russell were mistaken.

Any objects or world unobserved don't exist. They are imagined or believed to exist. — Corvus

Why should I believe in the existence of an object in the world that I have never observed existing?
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Indirect realism's problem is using sense data as the medium of perception, which doesn't make sense. — Corvus

It may be that your problem with Indirect Realism is, as you said on page 1: "You end up having 2x copies of every object in your perception, and wonder which one is the real object."

But this is not the case for the Indirect Realist. There is no medium of perception. There is just perception.

When the Indirect Realist perceives the colour red, for example, they are not perceiving a representation of the colour red, they are directly perceiving the colour red.

Anything otherwise would lead into the homunculus problem of infinite regression.

What the Indirect Realist does believe is that there is something in the world that has caused them to perceive the colour red, but it is unknowable whether this something in the world is actually red or not. The Indirect Realist reasons that it is not, but cannot know for sure.

In a sense, the colour red that is directly perceived is a representation of the unknown something in the world, which may or may not be the colour red.

There is only one object of perception for the Indirect Realist, and that is the direct perception of the colour red.

In Ideal Realism, unperceived objects such as the country of Australia or the object Eifel Tower don't exist until observed or perceived. — Corvus

I don't think that Australians will be happy to know that they don't exist because an Ideal Realist in the Kerguelen Islands has never heard of them.
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Ideal Realism also says that we perceive the world with experience via the bodily sense organs loaded with ideas, not direct. — Corvus

This sounds like the existing term "Indirect Realism" (Wikipedia - Direct and indirect realism)

I would brand this way of seeing the world and perception as Ideal Realism — Corvus

"Ideal Realism" as described sounds like the existing term "Direct Realism" (Wikipedia - Direct and indirect realism)

Even the Direct Realist can dream and imagine.

It's actually quite easy if you follow my disclaimer since understanding of such a world does not require the understander to lack a mind. It just requires the world under consideration to lack the mind. — noAxioms

We agree that there is the domain of the mind and the domain of a mind-independent world.

The problem remains that your disclaimer requires the mind to be able to understand something that we agree by defintion is independent of the mind, ie, to understand existence in a mind-independent world.

This is the same problem of how is it possible to know the unknown.

Your disclaimer makes the OP logically impossible to answer.

Disclaimer: I am not talking about ideals or the mental abstraction of Santa or anything else..........................Such an argument requires an epistemological/empirical definition of existence, and I am attempting a discussion on a metaphysical definition. — noAxioms

If we had no perceptions, we would have nothing to reason about. But we do have perceptions. Idealism reasons that there is no mind-independent world. Indirect Realism reasons that our perceptions are only representations of any mind-independent world. Direct Realism reasons that our perceptions are a one to one correspondence with the mind-independent world.

As you say, any reasoning about E1 to E6 combining Idealism, Direct Realism and Indirect Realist would result in contradictions.

Sounds like combining them would create contradictions, not just convolution. — noAxioms

Only the Direct Realist argues that we can understand existence independent of the mind, yet this is a logical impossibility. It is logically impossible because any such understanding of a mind-independent world depends on the mind understanding something that is mind-independent.

This topic is about ontology and realism, and not about perception. — noAxioms

Our only knowledge about ontology and realism is founded on our perceptions, and our only understanding of the metaphysical depends on the epistemological/empirical.

Got it. Anything not proven (pretty much everything) doesn't count as 'knowing', so you know nothing...................................I certainly don't identify with any of those labels. — noAxioms

E1 to E6 can be interpreted from the position of Idealism, from the position of Direct Realism and from the position of Indirect Realism. Each interpretation will be different. Any interpretation of E1 to E6 that is based on a combination of Idealism, Direct Realism and Indirect Realism will become unnecessarily convoluted.

If you don't identify with either Idealism, Direct Realism or Indirect Realism, which theory of perception are you using?

My understanding of Idealism, Direct Realism and Indirect Realism agrees with an article from philosophy A level.com, but there are many articles on these three theories of perception.

This A level philosophy topic looks at 3 theories of perception that explain how we can acquire knowledge from experience, i.e. a posteriori. They are: Direct Realism, Indirect Realism and Idealism

The theories disagree over the metaphysical question of whether the external world exists (realism vs. anti-realism) and the epistemological question the way we perceive it (direct vs. indirect).

Direct realism is the view that the external world exists independently of the mind (hence, realism). And we perceive the external world directly (hence, direct)

Indirect realism is the view that the external world exists independently of the mind (hence, realism). But we perceive the external world indirectly, via sense data (hence, indirect)

Idealism is the view that there is no external world independent of minds (so it rejects realism – both direct and indirect). We perceive ideas directly.

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I got a quote that suggests that Meinong is perhaps using E4 as his definition of exists — noAxioms

Meinong uses the terms "exists", "subsists" and "absists".

We can divide the Universe into the domain of the mind and the domain of the mind-independent.

Objective reality in E1 can refer to both the domain of the mind and the domain of the mind-independent.

By the objective state of this universe in E4, do you mean the domain of the mind or the domain of the mind-independent?

I understand that Meinong uses "exist" to refer to the domain of the mind-independent.

The only quality of the apple I'm interested in is whether or not it exists, and which definition of exists is being used when justifying the assessment one way or another...................................almost everybody uses definition E2 when the say 'exists', but then convince themselves that some other definition must also be the case. — noAxioms

There are three theories of perception, Idealism, Direct Realism and Indirect Realism.

I don't think that either Idealism or Direct Realism are philosophically valid. Therefore, the question of the definition of "exist" must of necessity be considered from the position of Indirect Realism.

E1 The only objective reality I know about exists in my mind, although I believe that an objective reality also exists in a mind-independent world.

E2 The only things I know about exist in my mind.

E3 The only things that have predicates exist in my mind.

E4 The only objective state of this universe I know about exists in my mind, although I believe that an objective state of the universe also exists in a mind-independent world.

E5 I know the state that exists in my mind, and believe that it was caused by a prior state that existed in a mind-independent world.

E6 I know the domain that exists in my mind and believe that there is another domain that exists in a mind-independent world

This presumes an epistemic definition of cause, not a metaphysical one. — noAxioms

I see a broken window and can imagine several possible causes, but don't know the actual cause. A detective visits the scene of a crime and can imagine several possible causes, but doesn't know the actual cause.

As an Indirect Realist, I see the colour green and can imagine several possible causes, but don't know the actual cause. The Direct Realist, on seeing the colour green knows that green was the actual cause.

For the Indirect Realist, epistemology limits metaphysical knowledge. For the Direct Realist, their metaphysical knowledge is not epistemologically limited.

You claim this indirect realist knows nothing about the thing, and yet he holds a belief that it exists in this way. Isn't that irrational? Is the belief just a matter of faith then?...........................All that said, identifying as a kind of realist doesn't define what is meant by 'real'. What is real? In what way is it real (R1-R6)? Some of those definitions have empirical backing and some don't. — noAxioms

Knowledge is justified true belief. As an Indirect Realist, I believe that things exist in a mind-independent world and I can justify my belief. But as my belief may or may not be true, I cannot call it knowledge.

Yes, my belief that there are things in a mind-independent world is in a sense a matter of faith, as a religious person's belief in a god is a matter of faith, but that doesn't mean it is irrational.

On the other hand, I know my perceptions of colour, smell, taste, etc, which are not matters of either belief or faith.

I know that my perceptions are real, and believe that there are things in a mind-independent world that are also real.

Generally, "real" and "exist" are synonyms, though there is nothing to stop anyone from redefining them.

Likewise, my injury would not have occurred had any of the four causes not have happened. — noAxioms

You are proposing Overdetermination, which is philosophically problematic. A solution to the Overdetermination problem would make a good PhD thesis.

From the Wikipedia article on Overdetermination

Overdetermination occurs when a single-observed effect is determined by multiple causes, any one of which alone would be conceivably sufficient to account for ("determine") the effect.
There are many problems of overdetermination. First, overdetermination is problematic from the viewpoint of a standard counterfactual understanding of causation, according to which an event is the cause of another event if and only if the latter would not have occurred, had the former not occurred.
Second, overdetermination is problematic in that we do not know how to explain where the extra causation "comes from" and "goes". This makes overdetermination mysterious.

The question never gets answered. If EPP holds, how is EPP justified? If it doesn't hold, how do we know the horse exists? How does Meinong (somebody known to deny EPP) justify the horse as being in a different domain than the unicorn? — noAxioms

As I believe that neither Idealism nor Direct Realism are valid, the question can only be looked at from the perspective of Indirect Realism.

Q1 The EPP principle is that there cannot be properties without being attached to something existing. How is this principle justified

The Indirect Realist perceives a set of properties in the mind, such as being four legged, being maned, being hoofed, etc. The Indirect Realist believes that there is a thing-in-itself existing in a mind-independent world that has caused them to perceive this set of properties in their mind, but they know nothing about any thing-in-itself.

The Indirect Realist cannot justify the EPP principle, as although they do know that there are properties in their mind, they don't know if these properties are attached to something existing in a mind-independent world. There may be, or there may not be.

Q2 If there can be properties in the absence of something existing, how do we know that horses exist

The Indirect Realist may consistently perceive in their mind the constant conjunction of the set of properties being four legged, being maned, being hoofed, etc.

They can then attach the mental concept "horse" to this set of properties.

When the Indirect Realist is thinking about a "horse", they are thinking about a set of properties. They are not thinking about an unknown thing-in-itself that may or may not be existing in a mind independent world.

Q3 If there can be properties in the absence of something existing, how do we know that horses are in a different domain to unicorns

The Indirect Realist may consistently perceive in their mind the constant conjunction of the set of properties being four legged, being maned, being hoofed, not being horned, not only being in a book, etc. They can then attach the mental concept "horse" to this set of properties.

They may also consistently perceive in their mind the constant conjunction of the set of properties being four legged, being maned, being hoofed, being horned, only being in a book, etc. They can then attach the mental concept "unicorn" to this set of properties.

The domains of horse and unicorn are different. One domain can include the property "not only being in a book", whilst another domain can include the property "only being in a book".

That doesn't mean there's no apple. It just means that we don't know the true nature of the apple. Common referent (the fact that more than one mind can experience the object) is solid evidence that it is there in some form. You can deny the common referent, but that becomes solipsism. — noAxioms

I assume you are referring to apples in a mind-independent world rather than "apples" in the mind.

It is a logical contradiction to say that we don't know the true nature of the apple, but we do we know that the true nature of the thing-in-itself is an apple.

We perceive an "apple" in our minds. Both the Direct and Indirect Realist agree that there is a thing-in-itself in a mind-independent world that has caused us to perceive an "apple" (ignoring dreams and hallucinations).

The Direct Realist says that there is a one to one correspondence between what they perceive and the thing-in-itself, meaning that the true nature of the thing-in-itself is an apple. The Indirect Realist doesn't know the true nature of the thing-in-itself.

Regardless of the true nature of the thing-in-itself, it can be labelled as an apple, which means that the label is the common referent, not the thing-in-itself.

For example, suppose the true nature of a thing-in-itself is being green, but this thing-in-itself has been labelled pink. Suppose person A perceives the thing-in-itself as purple and person B perceives the thing-in-itself as red. Person A and person B can have a conversation about the pink object because that is its label, even if the true nature of the thing-in-itself is not pink and neither person perceives the thing-in-itself as pink.

That there is a common referent, the label pink, is not evidence about the true nature of the thing-in-itself.
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So you agree that there are at least four causes to my injury? — noAxioms

When walking on wet gravel looking at a coyote, you slip. Simplifying the situation, you walk on gravel and slip. What is the cause of your slipping?

Walking and not gravel - don't slip
Walking and gravel - slip
Not walking and not gravel - don't slip
Not walking and gravel - don't slip

How many causes are there to your slipping? Walking is not a cause of your slipping, as you could have been walking on asphalt. Gravel is not a cause of your slipping as you may not have been walking. Walking on gravel is the cause of your slipping.

Walking on gravel is the single cause of your slipping
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You talk endlessly about indirect realism and information flow, but not how any of that leads to a conclusion of the necessity of a single cause for any effect. — noAxioms

Forwards in time, a single cause has a single effect. For example, a snooker ball moves in a pre-determined way when hit by a snooker cue.

Backwards in time, a single effect has more than one possible cause. For example, knowing the positions of the snooker balls on a snooker table gives no knowledge about the positions of the snooker balls on the snooker table at a prior time.

An effect is overdetermined if it has two or more distinct, sufficient causes (Wikipedia - Overdetermination). As the Wikipedia article notes, there are many problems with
overdetermination, and PhD's have been written about the topic.

But you claim exactly that. "For the Indirect Realist, apples only exist in the mind.". Do clarify this contradiction then. — noAxioms

The Indirect Realist, being a Realist, believes that there is a mind-independent world and all our knowledge about such a mind-independent world arrives as experiences through our senses.

Because of the asymmetric flow of information in a causal chain between a thing-in-itself in a mind-independent world and the experiences in our senses, we can never know the true nature of any thing-in-itself.

For example, I could consistently experience in my senses the constant conjunction of a circular shape, a sweet taste, a silky touch, an acrid smell and an absence of sound. For convenience, this consistent set of properties could be named "apple".

My only knowledge of the concept "apple" has come from experiences in my senses, not from knowledge of things-in-themselves in a mind-independent world. I can say that the thing-in-itself is an apple, but that is not to say that in reality the thing-in-itself is an apple.
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Tell me why

Tell me why my example is wrong, that nothing on my list caused my injury. — noAxioms

My argument against Direct Realism is that one effect, such as a broken window, can have more than one possible causes, such as a rock, bird or window cleaner. Knowing the window is broken doesn't of itself give us knowledge as to what caused the window to break.

There is a temporal direction of flow of information in a causal chain.

In a deterministic world, there is a direct flow of information in a causal chain forwards in time. I agree that choosing to walk, a recently repaved road, a shoulder not properly filled and a coyote in a distant field all inexorably lead to your breaking your hip.

There is no direct flow of information in a causal chain backwards in time. Knowing you broke your hip doesn't of itself give us knowledge as to what caused your hip to break. There could have been more than one possible cause, such as being hit by a car, slipping on wet grass, being distracted by a coyote, etc.

In a deterministic world, there is a causal chain from your choosing to take a walk to your breaking a hip, but it is also true that there is a causal chain from the Big Bang to your breaking a hip.

In that sense, the Big Bang is as much a cause of your breaking a hip as choosing to take a walk. If it is true as you say that it is empty and tautological to identify the Big Bang as the cause, then it must also be empty and tautological to identify your choosing to walk as the cause.

However, my argument against Direct Realism is that it relies on a symmetric flow of information in a causal chain. For example, Direct Realism relies on a stranger hearing that you have broken your hip and for the stranger to thereby know that the cause of your breaking your hip was your choosing to take a walk.

Direct Realism, being invalid, means that all our knowledge comes from experiences in our senses. We can then reason about the possible causes of such experiences. As all our knowledge about existence and properties are mental abstractions, this makes it difficult to discuss existence and properties when your disclaimer prohibits discussion about mental abstractions.
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Yes. E2, E4, E5, E6 all have a domain. E1 is the only one that lacks it, and maybe not even then. Not sure how to classify E3, since it seems to be a self-referential domain. — noAxioms

E1 - "exists" may be defined as "is a member of all that is part of objective reality"
There is the domain of being within the mind and there is the domain of being within a mind-independent world.

E3 - "exists" may be defined as "has predicates"
A horse exists because it has the property of being four legged, being maned, being hoofed, etc. In Meinong's term "exist"
Sherlock Holmes exists because he has the properties of being a detective, being a pipe-smoker, being housed in 221B Baker Street, etc. In Meinong's term "subsists"
A round square exists because it has the property of being round and being square. In Meinong's term "absists".
There are the domains of exist, subsist and absist.

1) Don't go to a dictionary to answer definition questions from philosophy or science.2) This is a philosophical discussion, so a philosophical definition is expected, not a lay definition. — noAxioms

How is "exist" defined in philosophy. You refer to the SEP article on Existence. But the article concludes that there is no satisfactory philosophical meaning of "exist"

This entry began by noting that existence raises a number of deep and important problems in metaphysics, philosophy of language, and philosophical logic. The entry has examined some of those problems and surveyed a number of different accounts of existence. None of the theories surveyed is wholly satisfying and without cost.

I referred to the Merriam Webster Dictionary definition of "exist" as "to have real being whether material or spiritual", but you say that this is not a philosophical definition.

This leads to an impasse, where a topic is being discussed yet there is no general agreement as to what the words being used mean.
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1) The whole point of realism is that there is a real apple independent of mind, the actual nature of which is a matter of interpretation.2) It seems that any realist (direct or not) presumes something is real, that it exists............What does it mean to have mind independent existence?...............How much is EPP necessary to justify the stance?
3) For at least the 10th time, per the disclaimer, I am not discussing ideals.
4) I am not discussing idealism, and what you call indirect realism is what everybody else calls idealism.
5) You contradict yourself again, since you claim there is no mind-independent reality under what you call indirect realism, and in so claiming, you claim to know everything about it. — noAxioms

Idealism is about what exist in the mind and Realism is about what exists in a mind-independent world. There are Direct Realists and there are Indirect Realists. The Direct Realist, such as John Searle, knows that there is a mind-independent world and the Indirect Realist, such as Kant, believes that there is a mind-independent world. The Idealist, such as Berkeley, knows that there is no mind-independent world.

As an Indirect Realist, I don't claim that there is no mind-independent reality, but I do believe that there is a mind-independent reality.

The Direct Realist knows that there is a real apple independent of mind, whereas the Indirect Realist believes that there is something independent of the mind.

In your Disclaimer you write "I am not talking about ideals or the mental abstraction of Santa or anything else". This leads to an impossible situation, in that if we are not allowed to talk about mental abstractions, yet Santa only exists as a mental abstraction, then it becomes impossible to talk about Santa at all.

How does this relate to the EPP? The EPP principle is that something must exist in order for it to have properties. Within Realism, there is the mind and there is the mind-independent world. For the Direct Realist, apples exist in both the mind and a mind-independent world. For the Indirect Realist, apples only exist in the mind. If, as I believe, Direct Realism is not valid, then we can only consider existence and non-existence from the position of Indirect Realism. From the position of Indirect Realism, our only knowledge of existence and non-existence is as mental abstractions.
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1) I break my hip (an effect) because 1) I chose to take a walk that day 2) there was a recently repaved road 3) shoulder not properly filled 4) coyote in distant field...................You assert only one cause is possible. I list four (with there being more), and you don't counter it. — noAxioms

If there had not been a Big Bang, you wouldn't have broken your hip. It depends whether it is valid to say that the Big Bang was one cause of your breaking your hip?

I would agree that the cause of the snooker ball starting to move was being hit by a snooker cue, but I have more difficulty in saying that one cause of the snooker ball starting to move was the Big Bang.
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E6 "existential quantification", where 51 is not prime because there exists an even divisor that is neither 1 nor 51. — noAxioms

I think that Existential Quantification E6 points to an important feature of "existing", and that is the domain in which something exists.

Integers exist in the domain of numbers, even if integers don't exist in a mind-independent world. Sherlock Holmes exists in the domain of literature, even if Sherlock Holmes is non-existent in a mind-independent world.

Something can both exist and be non-existent, dependent on which domain is being referred to.

Definitions are descriptions about how certain words and terms are being used. The latter doesn't have a truth value to it. — noAxioms

EPP = existence is conceptually prior to predication. What does "exist" mean? The Merriam Webster defines "exist" as "to have real being whether material or spiritual".

I agree that a definition does not have a truth value, in that the definition is not intended to represent the world as it actually is.

But why does "exist" mean "to have real being whether material or spiritual" rather than "a woody perennial plant".

It is not possible to justify why a word means one thing rather than another apart from being asserted by either common usage or government institution.

I still maintain that definitions are unjustified assertions.
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That's a different question that 'do apples exist?". — noAxioms

I agree that "where do apples exist" is a different question to "do apples exist", but they are connected.

The EPP implies that non-existent things cannot have properties. Meinong argued that non-existent things can have properties. But what has causation to do with this question?

For the Indirect Realist, apples only exist in the mind. For the Direct Realist, apples exist both in the mind and a mind-independent world

For the Direct Realist, Santa doesn't exist in a mind-independent world, and can therefore be said to be non-existent. For the Indirect Realist, both apples and Santa exist in the mind, and therefore neither can be said to be non-existent.

The Direct and Indirect Realist have different attitudes about non-existence.

My argument is that the Direct Realist position towards non-existence cannot be valid, because Direct Realism itself is not a valid philosophical position, in part because of the problem with causation.

This is why causation is part of the topic about non-existent things.
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I break my hip (an effect) because 1) I chose to take a walk that day 2) there was a recently repaved road 3) shoulder not properly filled 4) coyote in distant field......................In all my examples, there are multiple causes, each of which is necessary for the effect. — noAxioms

Both Indirect and Direct Realism have different approaches to non-existence, but I don't believe that the Direct Realist approach is valid, partly because one effect can have more than one possible cause.

Specifically, on seeing the colour red, the Indirect Realist accepts that they may not know the cause because one effect may have more than one possible causes. For example, a migraine, a green tree with the light passing through a stained glass window or a yellow field at sunset. The Direct Realist, however, argues that they know the cause was a red colour on the belief that one effect can only have one cause.

You make my argument for me in saying that one effect, breaking a hip, can have more than one cause, such as taking a walk, a repaved road, a badly repaved road and a coyote.

Once Direct Realism has been set aside, the Indirect Realist approach to non-existence can be further investigated.
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Things existing only in the mind or not is idealism, a valid view but one explicitly not being considered, per the disclaimer in the OP. — noAxioms

The EPP infers that non-existent things cannot have properties. Meinong argued that non-existent things can have properties.

Everything we know about the world is because of what we experience in our senses.

There are two distinct approaches, that of the Indirect and Direct Realist. The Direct Realist believes they can know what exists in a mind-independent world, and the Indirect Realist disagrees.

I believe that the problem of causation shows that Direct Realism is not valid, meaning that there is no alternative to Indirect Realism.

Non-existence can only be investigated from the position of the Indirect Realist.

Given so many definitions, the reader probably presumes his own definition instead of yours. — noAxioms

It would be an impossible task for me to persuade everyone that "thoughts exist". All I can do is assert that "thoughts exist".

To cover myself, I could give a definition, such as because "I know about it". But this is no more than a tautology.

Definitions are really no more than unjustified assertions.
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I'm especially interested in how you justify that there can be no more than one effect...Also, what relevance does this quibble have to do with the topic of existence? — noAxioms

Where do apples exist? The Direct Realist says apples exist both in the mind and in a mind-independent world. The Indirect Realist says apples exist only in the mind.

I don't accept Direct Realism as it depends on one effect having only one possible cause. This is where causation comes into the topic.

Why do I think that one cause has one effect? Imagine a snooker cue hitting a snooker ball. The game of snooker depends on one cause having one effect.

Over-determination is the situation where one effect has been determined by more than one cause. (Wikipedia - Over-determination). PhD's have been written about the problem.
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SEP article on existence, section 1 — noAxioms

:up:
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I break my hip (an effect) because 1) I chose to take a walk that day 2) there was a recently repaved road 3) shoulder not properly filled 4) coyote in distant field....................It isn't a path, it's a network. I gave four causes of my hip injury which wouldn't have happened given the absence of any of them. — noAxioms

Scenario one
1) You left the house for a walk.
2) You could have walked on the road or through the field. You walked on a road.
3) You could have walked in the centre of the road or on the unfilled shoulder. You walked on the unfilled shoulder of the road.
4) You could have been looking to houses the left where there was no coyote or to the field on the right where there was a coyote. You looked to the right.

Scenario two
You left the house for a walk, slipped on wet grass and broke your hip. You could have broken your hip even if there had been no coyote.

Scenario three
Even if there had been a coyote in the field to the right, you could have looked to the houses on the left, not seen a coyote, but seen a robbery, and then broken your hip.

Why relevant to existance? Do apples exist only in the mind, as the Indirect Realist says, or both in the mind and mind-independent world, as the Direct Realist says?

There is the commonly held principle (does it have a name? "EPP" if not) that existence is conceptually prior to predication, prior to it having any property at all. — noAxioms

The EPP
The EPP states that existence is conceptually prior to predication.

1) You say that this means that there must be existence before there are properties.

2) But equally, it could be the case that there must be properties before existence.

Why do you think 1) rather than 2)?

Why do you think that the existence of x is separate to the properties that x has?

Existential Quantification
In the domain of numbers, there is something x that exists that has the properties of being an integer and of being even. This something x exists in the domain of numbers, regardless of whether numbers exist in the world or are non-existent in the world.

In the domain of literature, there is something x that exists and has the properties of being a detective, of having Mrs Hudson as a landlady and of being a pipe-smoker. This something x exists in the domain of literature, regardless of whether literature exists in the world or is non-existent in the world.

Something x that exists in a domain that is non-existent in the world could be called "subsisting".

We don't ever just perceive the color red..............Judgements involve integrating all percepts into a consistent whole experience of the world. — Harry Hindu

True, both the Indirect Realist and Direct Realist are able to successfully drive through the city centre.

It is a philosophical question. Both the Indirect and Direct Realist may perceive the colour red at a traffic light, but what exactly is the nature of the thing-in-itself in the world that is causing them to see the colour red?

This is not something the driver of the car needs to think about. All they need to know when they arrive at the traffic light is whether they perceive red, orange or green.

It may well be that the thing-in-itself is in reality a yellow leprechaun, but as long as the driver consistently perceives the colour red, they will be able to successfully navigate the world.
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What does a direct realist do when they say the chocolate ice cream is delicious but someone else says it is disgusting? Is the direct realist talking about the ice cream or their mental state when eating it? — Harry Hindu

Exactly. Another reason against Direct Realism and for Indirect Realism.

A raw assertion without even a definition of what sort of 'exists' is being presumed. I am looking for justified statements, not opinions. — noAxioms

True. My saying that "thoughts exist" is a raw assertion without any definition of either "thoughts" or "exist".

But considering books have been written about the nature of thoughts and existence, I think my trying to define these terms would make my post far too long.

I can only hope that the reader understands what I mean by saying that "thoughts exist".
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So things that are non-mythical determines what exists?............This uses an anthropocentric definition of 'mythical'....................Being nonexistent and being currently extinct are very different things. — noAxioms

I would hope that few would argue with my saying that unicorns are mythical creatures.

For Meinong, something being mythical makes it subsist.
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Maybe we should let them (in their copious numbers) defend the position then. — noAxioms

Yes, Direct Realists should defend their position on the Forum.
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Perhaps we are speaking past each other. I break my leg. That causes 1) pain, 2) doctor work 3) financial troubles 4) missed days at work 5) cancelled ski trip. — noAxioms

My assumption is that in a deterministic world one cause has one effect and one effect can have more than one possible causes.

This is the core of my argument against Direct Realism.

Your example is about one event having more than one effect, which I agree with, as it supports my argument against Direct Realism.

The question is, can breaking a leg be said to cause cancelling a ski trip. After all, there is no necessary reason to cancel a ski trip just because you broke your leg. Breaking a leg may contribute to your decision to cancel your ski trip, but it would be wrong to say that breaking your leg caused you to cancel your ski trip.

Books have been written about the meaning of "causation", including the SEP article The Metaphysics of Causation
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You seem to be interpreting the word 'prior' to mean 'at an earlier time', which is not at all what the principle is saying — noAxioms

You say "There is the commonly held principle (does it have a name? "EPP" if not) that existence is conceptually prior to predication, prior to it having any property at all."

One of the accepted meanings of "prior" is "at an earlier time".

Do you have a source that establishes the principle that existence is conceptually prior to predication to help me understand how the terms have been defined?