current problem as I see it is that semantic direct realists have muddied the waters by trying to adapt direct realist terminology to mean something very different — something which doesn't actually contradict the phenomenology or epistemology of indirect realism. — Michael

That's my take too

am well aware that I am directly looking at the colour red.

As an Indirect Realist, — RussellA

Then, why are you an indirect realist?

Then, why are you an indirect realist? — Corvus

As an Indirect Realist, when I look at the colour red, I am directly looking at the colour red. I am not indirectly looking at the colour red.

When I feel pain, I directly feel pain. I don’t indirectly feel pain.

Both the Direct and Indirect Realist would agree that we directly look at the colour red. They would, however, disagree where this colour red exists. The Direct Realist would say that the colour red exists in a mind-independent world. The Indirect Realist would say that the colour red exists in the mind.

If the Indirect Realist did say that they only indirectly see the colour red, then they would fall into the homunculus problem, and trap themselves into saying that they are seeing a representation of a representation of a representation, etc.

I see the colour red because a wavelength of 700nm entered my eye, not because the postbox is red. It may be that when you look at a postbox and a wavelength of 700nm enters your eye, you see the colour purple, but this I will never know, as I can never know what exists in your mind.

We both look at the same postbox and the same wavelength of 700nm enters our eyes. I see the colour red and you see the colour purple. How do we decide whether the postbox is actually red or purple?

We ought to remember that we don’t just see ships, we also see everything else in our periphery. This fact seems to be rarely mentioned and for some reason we’re supposed to consider objects in a void. That’s just not how it works.

All seeing must be direct, that is, there has to be some environment or medium that is viewed without something else in the way, or you simply won’t see at all. The indirect realist simply doesn’t know or doesn’t want to say what that environment or medium is, or with what parts of his body he views it with.

We both look at the same postbox and the same wavelength of 700nm enters our eyes. I see the colour red and you see the colour purple. How do we decide whether the postbox is actually red or purple? — RussellA

When you see colour of the postbox, and say it is red, and when I see it, and say purple. This is a a very peculiar case. Ordinary folks don't come across this type of problems in daily life.

But when it happens (which I doubt very much unless one of us are colour blind), it must be concluded that our perception of colours of the objects are personal judgement, rather than perception. You have already perceived the colour of the postbox, and it appears "red" to you, and you are making your personal judgement "The postbox is red."

For me the postbox appears "purple", hence I claim "It is purple", which is just a personal judgement on the content of my perception.

The colour is not in your mind or in my mind. It is on the postbox. Instead of talking about Direct and Indirect Realist, we need to know that there are different type of perceptions, and whether the perceived objects do exit in flesh in front of the perceiver, and can be interacted with, accessed to, and used by the perceiver.

I am now looking at my guitar which is red colour in front of me. I will never say the redness of the guitar is in my mind. It is on the guitar. And because it appears red to me, I say it is a red guitar.

Under the different lighting it may appear different colour to me. I will still say it is a red guitar. But it appears blue under the blue lighting. It is my personal judgement on the visual sensation.

Ok, so one objection to your view is that the assumed "perceptual relation" between a "mental state" and the object means that the experience would be indirect. — jkop

But my view is that no mental state is involved. That's the objection I'm making to other direct realists - they still make a mental state - an experience - a component of the perceiving relation. I'm not doing that - I'm saying the perceiving relation has two and only two relata: the perceiver and the perceived. We experience these relations obtaining - that is, we experience perceiving things - but the experience is not itself a relata in the relation.

Our experience is 'of' perceiving rather than constitutive of it. That's also why my view does not face the problem of accounting for hallucinations, as hallucinations are kinds of experience (whereas if one bakes the object of perception into an experience then - the objection goes - hallucinations would seem to be impossible (to the discredit of the theory).

My gripe is with direct realists, most of whom seem to me to be indirect realists in disguise.

I think indirect realism is false as an account of what it is that we're perceiving in normal cases of perception. When I look at a ship in the harbour it is the ship, not a 'ship in the harbour-like' mental state that I am seeing if, that is, it is to be true that I'm perceiving the ship. On my characterization, the indirect realist is someone who - one way or another - says that what you're perceiving is a mental state; the perceptual relation terminates in the mental state. By contrast, the direct realist thinks that in the regular case, it is the ship that you are perceiving. They standardly try and keep the relevant mental state in the picture, they just think you're somehow looking through it to the ship. In the same way as if I look at the ship through a telescope I am looking at the ship 'through' the telescope and not looking at a telescope, the direct realist wants to say that some of our mental states - those involved in seeing and touching primarily - are akin to telescopes or windows. They are involved, but they enable one to see through them to the world, rather than themselves being the objects of perception.

So, crudely, I take indirect realists to think we're looking at pictures of the world and (the current crop) of direct realists to think we're looking through windows onto the world.

I don't think the window pane view makes sense (perhaps it does and I have just yet to conceive of it properly). I cannot see how a mental state can operate like a window. For one thing, it's a state, not an object. It would be a category error to think our mental states are literally windows, then. Now the issue is how it could be that a mental state - a state of mind - could give one direct contact with an object. It can't be a mediator - it can't be by simply 'telling us' - about the object. For that's not perception. That's not direct contact. It can't be by modelling or in some other way resembling the object of perception (which is perhaps a coherent possibility - for perhaps a state of mind can resemble a state of a mind-external object). For again, we cannot perceive something by looking at a model of it, no matter how accurate the model. These are indirect ways of acquiring information about something, not direct ways.

If they try - and some do this - to say that the object itself is included in the experience, then we have a mind external object being said to be part of a mind-internal state. That just seems confused - as confused as thinking a note about a mountain contains the actual mountain. (Additionally, such views face problems accounting for hallucinations and a driven to extreme and ontologically embarrassing measures to do so).

Maybe they could say that the experience - the mental state - is constitutive of the two place perceptual relation between the perceiver and the perceived. For an analogy, if I desire a ship, then there is a two place relation there constituted by my desire. My desire is for a ship. It's my desire - so I am the efficient cause of the relation - and it's for a ship. But the desire is not a relatum within the relation. So maybe the direct realist could say something analogous: the perceiving experience is constitutive of the perceiving relation, a relation that has two relata.

I find that proposal quite interesting and sometimes it is my view. But it seems to run into problems accounting for hallucinations. For if it is the essence of such experiences that there is an object of perception, then given hallucinations seem to be identical experiences, then they would need to have an object too. Perhaps that's not too much of a problem for one could just say that in their case it is a mental object, not a mind-external one. That is, that in the hallucination case the perceiver is perceiving a mental image of a ship, not a ship.

Your diagram... why the potato? :wink:

I think the science clearly shows that colour, taste, smell, etc. are the product of our biology, causally determined by but very different to the objective nature (e.g. the chemical composition) of apples and ice creams. — Michael

We had this chat previously. Let;s look again at some philosophical weasel-words.

So the idea is that sugar is not really sweet, it just tastes that way to us.

See the word "really" there? what's it doing?

If we take it away we have "sugar is not sweet, it just tastes that way to us"...

Something has gone wrong here. sugar is not sweet, it just tastes sweet? Well, yes... that's what being sweet is - a taste.

"No, no, the sugar isn't sweet in itself!"

See the words "in itself" there? what'r they doing?

If we take them away we have "sugar is not sweet", which is false. Sugar is sweet.

Sugar has hydroxyl (–OH) groups which activate the T1R2/T1R3 GPCR on taste cells, triggering a calcium-mediated signalling cascade form which the nervous system learns certain activities, including seeking out sweet tastes and calling them "sweet" in contrast to "bitter" and "umami".

It's the chemical composition of sugar that makes it sweet, in interaction with a human. Being sweet is having a chemical structure that activates T1R2/T1R3 GPCR on taste cells.

Now nothing in this last, bolded paragraph implies that being sweet is not a property of sugar in itself or is not real.

Being sweet is not an illusion or hallucination. Sugar really is sweet.


So, Michael, is there anything in this with which you disagree? I hope not.

Being sweet is having a chemical structure that activates T1R2/T1R3 GPCR on taste cells. — Banno

That's not what naive taste realists (or naive colour realists with respect to colour) mean. The historical dispute between direct and indirect realism concerns phenomenology and epistemology, and these problems are neither solved nor dissolved by (re-)interpreting the phrases "is sweet" or "is red" as meaning "having the mind-independent properties to cause such-and-such physiological/mental phenomena in such-and-such organisms".

The phenomenological dispute between direct (naive) and indirect realists concerns whether or not a) there are mental phenomena and whether or not b) the qualities of these mental phenomena are (also) mind-independent properties of things like apples. Naive realists believe either that (a) is false or that (b) is true, and so that there is no epistemological problem, whereas indirect realists believe both that (a) is true and that (b) is false, and so that there is an epistemological problem. And I think that today's science of perception supports the indirect realist view (even if mental phenomena is reducible to neurological phenomena).

It is true that apples have the mind-independent properties to cause me to see particular colours and taste certain tastes, but these colours and tastes are nothing like these mind-independent properties. I can't really grasp these mind-independent properties at all (my vague "understanding" of the Standard Model notwithstanding). All I really grasp is my body's reaction to them.

..my view is that no mental state is involved. — Clarendon

My apologies, here"s the quote to which the objection was a reply.

With my view our experiences of perceiving are mental states, but the perceptual relationship itself is not. Thus cases of hallucination share with cases of experienced perception the same mental states, it is just that in the former there is no perceptual relationship there (and thus the experience constitutes a hallucination). — Clarendon

I can't make much sense of the above, hence my objection. Your opening post, however, is fairly clear. So perhaps my failure to make sense of the quote has to do with the choise of words?

By the way, are you familiar with Searle's philosophy of perception? I think it clarifies some of the mess in talk of perception. For example, he distinguishes between two different senses of the word 'experience'. In its constituitive sense (e.g. a brain state from which an experience arises) there's an experience in both the veridical case and in the hallucination case. But in its intentionalistic sense (i.e. what the experience is about) nothing is experienced in the hallucination case, only in the veridical case.

You have a penchant for telling naive realists what they think. I'm not sure that they would agree with you. But then, it's not all that clear who "they" are.

Extensionally, being sweet is the very same as having a chemical structure that activates T1R2/T1R3 GPCR on taste cells.

It's not clear what the intensional difference is. We talk in very different ways in cooking and in biochemistry. Yet the two meet. Intensionality might be no more than a different language game.

Here I am purposefully deflating the phenomenology.

Why not just say that the babe has not yet learned to see the ship, and doesn't do so until they do so under a description? — Banno

Yes, though maybe we should use scare-quotes: "The babe has not yet learned to see 'the ship' and doesn't do so until they do so under [that] description." This allows that the kid has some kind of visual experience before the learning.

What we call a "ship" just is the sort of thing that we see. — Banno

OK, again adding that on occasion we see things that we can't conceptualize without further instruction.

So the claim is: when I see a ship, I am directly in contact with the ship itself, not with a representation, sense datum, or mental model of it. — Banno

A lot of the foofaraw here seems to hinge on "in contact." One of those terms that can be used in many contexts to mean many things. Certainly there is no ship (not even a "ship") pressing against my eyeballs when I see one; it can't be that kind of contact we mean. But why should it be? The appropriate kind of contact is, precisely, perceptual contact, and I agree it doesn't help much to interpose "representation" or "datum".

But I have some sympathy with those who want to. I think they're trying to emphasize the fact that our contact with what we perceive doesn't provide us with certainty about the experience. There's the idea that, if I had the right kind of direct perception, I couldn't be wrong. Instead, I perceive a ship . . . but wait a minute, no I don't. Fair enough. But I don't think the language of "sense data" or "indirect perception" is the best way to keep this distinction in mind.

No need to apologize. What I was trying to get across - not very clearly - in that quoted passage is that the mental experience of perceiving is 'of' perceiving rather than constitutive of it. The idea being that there is no mental state involved in the perceptual relation (this is how directness is achieved). But that there is an experience 'of' the perceptual relation. In this way direct contact with the object of perception is preserved and at the same time the raw materials from which hallucinations can be made are still available.

I'm not at all confident in this view and am quickly persuading myself that perception is essentially experiential, it's just that the experience constitutes the perceptual relation. So just as a desire constitutes a relation (between the desirer and the object of their desire), likewise a perceptual state constitutes a relation between the perceiver and the perceived.

I am only superficially familiar with Searle's view. It doesn't sound quite right to me, even given my revised view. For he seems to be trying to get directness out of the content of a mental state, and that - to my mind - is never going to work. All that'll get one is aboutness, but not perception. I want to insist that perception is a relation that can only have two relata - the perceiver and the perceived. There's no room for anything else. If 'the perceived' is to be a mind-external object, then there's no room for a mental state among the relata, for the other relatum has to be the perceiver themselves (not some mental state of theirs). What I currently think - and this is a distinct view from the one I started with - is that the mental state can be constitutive of the relation. If it's constitutive of the relation, then it doesn't feature as a relatum within it (thus preserving directness).

So now what I'd say about hallucination cases is that they are cases of perception, it's just that what they are perceptions of are mental states, not mind-external objects. So a visual hallucination of a ship would be a perception of a mental image of a ship, whereas a perception of a ship would be a perception of a ship. The difference, then, between hallucinations and perceptions of mind-external objects is not that one is a perception and the other not, but that one is a perception of something purely mental (but indistinguishable from a perception of something mind-external), whereas teh other is a percpetion of something mind-external

A lot of the foofaraw here seems to hinge on "in contact." — J

Yep. It helps to talk of the other senses - a suggestion from Austin. We already used the taste of sugar being sweet - the contact is pretty direct there. Touch provides an alternate example, rough against smooth.

Perhaps the problem is the expectation of certainty.

Sorry, I probably won't wade into this discussion, but I just so happened to have been listening to a New Books in Philosophy podcast on a related topic and thought that you and others might want to check it out (and/or the book itself):

M. Chirimuuta, Outside Color: Perceptual Science and the Puzzle of Color in Philosophy

What is color? On the one hand it seems obvious that it is a property of objects - roses are red, violets are blue, and so on. On the other hand, even the red of a single petal of a rose differs in different lighting conditions or when seen from different angles, and the basic physical elements that make up the rose don't have colors. So is color instead a property of a mental state, or a relation between a perceiving mind and an object? In Outside Color: Perceptual Science and the Puzzle of Color in Philosophy (MIT Press, 2015), M. Chirimuuta defends an ontology of color that aims to capture the ontology implicit in contemporary perceptual science. Chirimuuta, an assistant professor of history and philosophy of science at the University of Pittsburgh, argues for color adverbialism, in which color is a property of an action-guiding interaction between an organism with the appropriate visual system and the environment. On her view, color vision is not for perceiving colors; it provides chromatic information that helps us perceive things.

You have a penchant for telling naive realists what they think. — Banno

I'm explaining the historical distinction between direct and indirect realism, and how each position addresses the epistemological problem of perception. Locke's distinction between primary and secondary qualities is a fitting example of indirect realism, with his direct realist opponents rejecting this distinction.

There are legitimate phenomenological and epistemological differences between direct and indirect realism that can only be addressed by a scientific study of the world, the body, the brain, and possibly the mind, and that cannot be "deflated" by some semantic argument that "X is red" means "X causes such-and-such an experience".

This is why I phrased my post carefully, and why I posted the picture I did. The relevant dispute between direct and indirect realism concerns whether or not a) there are mental phenomena and whether or not b) the qualities of these mental phenomena are (also) mind-independent properties of things like apples. If (a) is true and (b) is false as indirect realists claim then there is an epistemological problem.

There are legitimate phenomenological and epistemological differences between direct and indirect realism that can only be addressed by a scientific study of the world and perception, and that cannot be deflated by some semantic argument that "X is red" means "X causes such-and-such an experience". — Michael

So you claim. Yet the deflation is set out before you. Hmm.

Yet the deflation is set out before you. — Banno

It's not. It's a red herring that distracts from the actual phenomenological and epistemological questions. Do mental phenomena exist, and if so are its properties the mind-independent properties of things like apples (or do they in some sense resemble them)? If mental phenomena do exist and if its properties do not resemble the mind-independent properties of things like apples then indirect realists are correct and there is an epistemological problem of perception.

I am interested in hearing any objections to this 'proper' form of direct realism - perhaps it is not coherent or perhaps it has unacceptable implications. — Clarendon

My take of some relevant ancient history.

The strongest logical statement in philosophy comes from Parmenides. To paraphrase, Everything is, period. There is no else to this existential logic because Everything comprises all possible conceptions whether logical, verbal, psychological or physical.

The next strongest logical statement comes from the mouth of an unlikely source, "Après moi, le déluge". This represents the other, Protagorian existential absolute. Taken within their premises, these two absolutes are not debatable.

Unfortunately neither absolute gives any insight into their only object, nor do they suggest any relation or transition to the world we or I live in.

Plato replaced the One with the plurality of the Forms and also of objects, a multitude of sensible objects represented by Forms. But visible sensation of the material objects is indirect through circumstances, visual rays of sorts, and mental perception. Plato noted that this necessarily indirect sensation-perception cannot possibly yield personal certainty or knowledge because it is contingent on worldly intermediaries.

To perceive [see] something is to be in unmediated contact with it. I take that to be a [presupposed] conceptual truth that all involved in this debate will agree on.
...
With that in mind, a 'direct realist' is someone who holds that ... when I look at the ship I am directly aware of the ship itself. — Clarendon

So be it. Doing so eliminates the Platonic Formal and perceptual complexities and in the process makes Truth, Certainty, and personal Knowledge possible! Reasonably well defined philosophical objects can be logically acted upon. But only for the direct realist. The majority who insist on either naively obvious indirect or publicly derived Scientistic dogmas will point to their greater more popular world but can never have anything more than the probability of their opinion in that greater world.

I think that direct realism 'proper' would have to be the view that perceptual relations have 2 and only 2 relata: the perceiver and the perceived. That is, no mental experience features as a relata within it (for then you automatically get indirect realism) — Clarendon

In the strict sense (ignoring quotes of whatever outlier opinions) perception is a foreign word to direct realism that introduces a Trojan horse fallacy if admitted.

Do mental phenomena exist, and if so are its properties the mind-independent properties of things like apples (or do they in some sense resemble them)? If mental phenomena do exist and if its properties do not resemble the mind-independent properties of things like apples then indirect realists are correct and there is an epistemological problem of perception. — Michael

This is better - we are getting closer to the presumptions underpinning this picture of the world.

DO mental phenomena exist? Well, what sort of thing is a mental phenomenon? What is to count as mental phenomena? Once we decide that, we are on the way to being able to quantify over them and include them in out discourse. Whatever they might be, they are not apples. But can the notion be set out clearly?

Now I know what an apple is - at least well enough to cook apple crumble. Is there something I can do with, say, a mental phenomenon of an apple that I can't do with an apple? Well, I can post about them on a philosophy forum, I suppose.

Are we going to say I can use my mental-phemonenon-of-apple to make mental-phenomenon-of-apple-crumble?

And if I did so, what have I done that is not equally well set out by saying I used apples to make an apple crumble?

See how the mental phenomena loses its puff? That's the deflation mentioned above.

It's all in the crumb.

The difference, then, between hallucinations and perceptions of mind-external objects is not that one is a perception and the other not, but that one is a perception of something purely mental (but indistinguishable from a perception of something mind-external), whereas teh other is a percpetion of something mind-external — Clarendon

I think you over complicated this scenario. The essential difference between a hallucination and the perception of a mind-external object is in the case of a hallucination we have the absence of a "mind external object." In one case, the success of calling out an apple when an apple is present shows we perceived an object. In the other case, the error of calling out an apple when none is present shows we may have hallucinated, thus, we did not perceived an object called "apple."

I'd say that overcomplicates things.

I take it we can agree that hallucinating a ship and perceiving a ship are indistinguishable experiences. So we need to explain why the hallucinating episode and the perceiving the ship episode would be indistinguishable.

My view does this: they are both perceiving relations, it's just that one has as its object an actual ship, and the other has a mental image of a ship as its object.
On my view the perceptual experience 'is' a perceiving relation (and it is precisely because of this that the experience doesn't feature as a relatum within the relation - for it is essential that the relation constitutive of perceiving have only 2 relata). Thus, the most straightforward way for an experience to be indistinguishable from perceiving an object is for it to be the same kind of experience - a perceiving experience - but with an identical appearing object (a mental image of a ship).

But on your view in the hallucinating case there is no object at all - but then that means it is not a perceiving relation and thus is a quite different kind of experience from the perceiving one. So why would it be indistinguishable from it?

It seems to me that you only have two options, one of which introduces extra clutter and the other of which renders the perceptual case - the good case - indirect. The first option is simply to posit a quite dfiferent mental state from the experience of perceiving and say that it can nevertheless be indistinguishable from it. But now you've got two kinds of state, not one. That's more complicated than my view.

The other option is to say that there is one and the same mental state, it's just that in one case there is nothing answering to its content out there in the world, whereas in perceptual case there is. But that's the indirect realist view in which it turns out that we never really perceive mind external objects at all.

Searle's view. It doesn't sound quite right to me, even given my revised view. For he seems to be trying to get directness out of the content of a mental state, and that - to my mind - is never going to work. All that'll get one is aboutness, but not perception. — Clarendon

I'd say Searle's view is that the content of a visual experience is set by conditions of satisfaction, such as the object's presence in the visual field. Its appearance is fixed by angle and distance of view, available light, surface properties etc. and while the observer's brain and eyes enable the experience, the content of the experience is fixed by the object and its properties. We can't detach content of experience from object's appearance, hence direct. The relation between observer and object is always direct.

But that last bit - the direct bit - is stipulated. I don't see how it would be direct.

What Searle does is just emphasize the distinction between perceiving a mental state and perceiving its contents. He seems to think that so long as the content of the mental state is what one is perceiving - and its content is 'about' a ship and this content is satisfied in the right kind of way - then one is directly perceiving it. But that's precisely the issue: I'm arguing that simply won't work. I'm not denying that there are such mental states or that when we are in them it is the contents rather than the state that we are aware of; I'm just denying that when that occurs we're perceiving an object as opposed to looking at an image of one.

For example, these words are just patterns. But you're probably not seeing them as patterns, but rather as messages. That distinction - between the patterns and the content - is essentially the same as between a mental representation and its representative contents. Clearly, however, one cannot perceive a ship by reading a note about it, even if in reading it one is not noticing the patterns but only really noticing the content.

So, it's not enough for Searle to point out that when we have a mental image of a ship it is the content of the image that we 'see' and not the mental state. That's true - I grant all that. The point is that we're still dealing with a mental note 'about' a ship and not a ship itself. Thus, there is no direct contact between the perceiver and the perceived, much though Searle may insist otherwise.

There has to be but two relata in a direct relation, otherwise it's simply not direct. Mental states can't perceive things, only minds can. Thus, in a perceptual relation one of the two relata must be a mind. That leaves the object that is perceived as the other. Those are the only two relata a perceptual relation can contain (otherwise there's no directness). Introduce a third relatum - a mental state by means of which one becomes aware of the object - and one has indirect contact, not direct.

Mental phenomena are either reducible to neurological phenomena or are emergent. They are what occur when we dream, and what don’t occur when we are unconscious (even if our taste buds are chemically reacting to apples).

These mental phenomena have qualities that, although often causally determined by particular mind-independent properties of mind-independent objects, are neither identical to these mind-independent properties nor similar to them.

Given the distinction and dissimilarity between the qualities of mental phenomena and the mind-independent properties that causally determine them, there is an epistemological problem of perception.

This is what indirect realists, both historical like Locke, and modern argue. And the naive realist, i.e. the phenomenological direct realist, disagrees, rejecting anything like the primary and secondary quality distinction. They claim that mind-independent properties are not just causally responsible for the phenomenology of experience but are actual constituents of it.

The newer semantic direct realists who try to turn the problem into one about language and the meaning of the English phrase “the apple is red” neither absolve naive realism nor refute indirect realism. They’re just addressing an unrelated and unimportant issue. The actual philosophical issue is one that applies to people without a language and/or from 100,000 years ago as well (even if they are not equipped to express the issue themselves), and to non-human animals with different sense receptors who may even see colours and taste tastes that we can’t even imagine.

Mental phenomena are either reducible to neurological phenomena or are emergent. — Michael

Why should we think this covers all the possibilities?

Again, with phenomena, and the presumption that somehow I observe "what occur when we dream, and what don’t occur when we are unconscious".

I don't observe my dreams; I have them. What doesn't occur when I am unconscious is consciousness, which is again not something I observe, so much as something I do.

You are taking these "mental phenomena" as granted. I would question them.

And along with them, the characterisation of direct realism.

I’m explaining what I believe most indirect realists believe. Mental phenomena exist and have qualities that are neither identical to nor similar to the mind-independent properties that causally determine them, and so the qualities of metal phenomena provide a misleading picture of the mind-independent nature of the world.

These are the substantial phenomenological and epistemological claims that direct realists dispute, and this dispute can neither be solved nor deflated by arguing that the English phrase “sugar is sweet” means “the chemical structure of sugar activates T1R2/T1R3 GPCR on taste cells”.

It’s a dispute that can only be addressed by a scientific study of the body, the brain, and sugar, and I think the current scientific view favours indirect realism over direct realism; the evidence is quite convincing that, whatever first-person experience is, it is not constituted of the mind-independent properties of distal objects (even if it is causally determined by them).

Ok. The problems for your position remain: mental phenomena as entities; phenomenology as representational; non-identity as epistemically problematic. You've reiterated them and then insulated them by an appeal to sociology. The challenges raised remain unanswered.

You've retreated back to the sociology, to "most indirect realists believe...", and there is little empirical data one way or the other. What we do have is evidence that philosophers overwhelmingly accept realism.. The same is unsurprisingly the case for physicist.

Philosophers appear to have moved past the direct/indirect realism dichotomy, and indeed past the realism/anti-realism debate. The deflationary arguments have brought a rejection of grand dichotomies, and a focus on local questions about representation, perception, normativity, explanation, and practice - to small, close conceptual work.

I take it we can agree that hallucinating a ship and perceiving a ship are indistinguishable experiences. So we need to explain why the hallucinating episode and the perceiving the ship episode would be indistinguishable. — Clarendon

Well, it is a good thing we don't learn what an hallucination is by evaluating our private experiences since they are indistinguishable from our veridical experiences. But somehow we actually do learn what they are, the advantages of learning a language in a community with other human beings.

My view does this: they are both perceiving relations, it's just that one has as its object an actual ship, and the other has a mental image of a ship as its object. — Clarendon

Yes, the typical imagery of the private theater that no one else can enter.

But on your view in the hallucinating case there is no object at all - but then that means it is not a perceiving relation and thus is a quite different kind of experience from the perceiving one. So why would it be indistinguishable from it? — Clarendon

Those are your words not mine. In principle, you cannot demonstrate to anybody that the two experiences are indistinguishable. However, what you do present is a metaphysical fiction that tries to explain why someone would claim they are perceiving an "apple" when it is not there.

I simply am stating that when someone is hallucinating they simply did not perceive what they claimed.

But if an explanation is needed, let's look no further than a naturalistic one. First, view the human as a color detecting machine, just like colorimeter. In both case, in order to detect color you need to standardize the machine. For example, when a child is learning colors, we present them with standardized swatches. They practice identifying the colors, learn how to verbalize their names, and with enough practice they are able to demonstrate to the human community their ability. Whether a colorimeter is operating as expected will also need to be check using standardized color solutions or filters.

Unfortunately, machines can break down or not put together well. The human can make incorrect color judgments, or the colorimeter can't make the correct reading. In either case, there is no need to construct metaphysical entities like "mental states" or "sense data" to explain what may be going wrong. I better route would be to understand the physical mechanism in which each machine is able to correctly make the necessary color judgments and repair as needed.