A visual circle is just an experiential effect of the right kind of external stimulation, just as a tactile circle is just an experiential effect of the right kind of external stimulation. I think it very wrong to think that things look (or feel) like something even when not being seen (or felt). — Michael

But objects do have shapes, and those shapes are important to how the objects interact with the world. When we see a circle, we see that shape because the light bounces off it that way. When we feel the shape, we can tell that it's rounded, and if a blind person walked around a shape, they would know they went in a circle.

The fourth point is where I think direct realism fails. The properties of the experience (colour, smell, taste, texture, shape) are properties of the experience and not properties of the external-world stimulus. The properties of the external-world stimulus are causally covariant with the properties of the experience, but they are not the same. For example, a sweet taste is causally covariant with the apple's chemical structure, but isn't a property of the apple, and a red colour is causally covariant with the apple's surface (and/or the reflected light), but isn't a property of the apple's surface (and/or the reflected light). — Michael

I would agree with that. But are there some properties that we do directly perceive, such as shape?

Each one of us has his own experiences. When we say that we both perceive something (i.e. that the sky is blue) what we mean is that we have similar experiences. Nothing else. — Magnus Anderson

What we mean is that we have similar color experiences when looking at the same sky.

It dissolves it because it puts to ground the untenable, philosophically atrophied distinction between the 'mental' and the 'thing itself'; the very question posed by the OP is an error. The challenge is not to answer it but to reformulate its terms entirely. — StreetlightX

I understand, but I don't see how it accomplishes that, since we do have sensory experiences which are not externally generated.

I'm asking for the distinction between perceiving a mind-independent object and perceiving a mental image. I don't get it. — Michael

When you dream, hallucinate, visualize or remember a tree, it's only available to you. When you perceive a tree, other people can also perceive it. Realists say this is so because the tree is mind-independent.

but then the former wants to say that the perception is of the external stimulation and the latter wants to say that the perception is of the experience. Except for the wording, I don't understand the difference. — Michael

It's whether the content of perception is the same as dreaming, hallucinating, etc. or not. What causes it is another matter.

If the indirect realist is correct, then we're seeing the equivalent of a dream tree, like when Morpheus tells Neo he's been living in a dream world. The only difference being that there's an external cause for the perception, which may be similar to the tree, or something entirely else, such as the noumena.

But if the direct realist is right, then what we see is what we get, within the limitations of our sensory organs (obviously science is still needed here).

As long as 'perception' continues to be spoken about as a 'mental', imagistic phenomenon - and not the bodily/physinomic, interactive, environmental, affective, anticipatory, and memory-laden process that it is - this thread will continue to be mired in aporia - as it currently is. — StreetlightX

I'm not sure how putting it in those terms dissolves the philosophical issue of what a perceived tree is, or the skeptical concern that we can't know. Also, we do experience mental* images, and when we see a tree, it can be similar in experience to having a hallucination or dream of a tree.

* Or image generated by our nervous system (or bodily organism), if you prefer. Meaning, it's not external to our being, and thus publically shared.

And what are dreams/hallucinations if not the occurrence of sense-data? — Michael

Agreed, and it's a problem for direct realism, far as I'm concerned. Disjunctivism is one way of dealing with that.

So are you saying that the image of a tree is the tree, or that there's no such thing as the image of a tree? — Michael

No, image of the tree is seeing the tree.

Repeating the claim "awareness is direct" doesn't explain what it means for awareness to be direct. — Michael

You perceive a mind-independent object, not a mental image, sound, etc.

So what does it mean for sense-data/qualia to provide "direct" (or for that matter "indirect") access to the tree? — Michael

Direct realists deny that there are sense-data. Your access to the tree is direct because you're not aware of some idea in the mind (sense-data), you're aware of the tree.

but beyond that, what's the difference between saying that the experience is direct or "just" a simulation? — Michael

The difference is what we're directly aware of when having a perception. The indirect realist has to make an inference to an external tree. The direct realist does not.

. As I see it, only philosophers ever bother with the issue in the first place. — t0m

That's like saying only mathematicians bother with questions like Fermat's last theorem.

Except that questions about whether we really perceive the real world do crop up among average people, and make it into literature and the media. You have people like Elon Musk claiming we're in a simulation and asking scientists to find a way out, or whatever.

Philosophy is like art, math and sport. They are activities humans engage in, but anyone can find those activities to be pointless, or meaningful.

They're just different ways to talk about the same thing. — Michael

But they're not. One is talking about a simulation running inside your head by which you're indirectly aware of an external world.

The other is talking about there being no simulation, just direct access to the external world.

The difference is meaningful and huge, because the first one allows skepticism and idealism a foot in the door, while the other closes the door. That's why Berkeley went after direct realism first.

Maybe it's not about making or doing everything the right way, whatever that might be, maybe it's about how we deal with these problems as we grow and gain more knowledge. — Sam26

Maybe that's because we have no choice in the matter? I wake up tomorrow and declare it's a new day, but I still have to deal with the consequences of yesterday. If I could hit the reset button, there are days I would do that. But nobody gets that choice, so we settle for a coping strategy and call tomorrow a new day where one has hopefully learned something from yesterday's mistakes.

But if gods forbid you run over a kid in the street because you looked down at your phone when the kid ran out in front of you, no amount of growth and making better decisions will bring that kid back. You can tell yourself whatever you want, but not having a reset button sucks big time for some things.

Other than that, I can't think of anything earlier than Descartes and his evil demon. And it was Berkeley that really seemed to set this issue rolling in any widespread way. — andrewk

Wasn't Berkley responding to Locke & Hume?

Also, discrepancies in perception are probably part of what motivated humans to start asking philosophical questions in the first place. At least Simon Blackburn and Daniel Dennett seemed to think the distinction between appearance and reality was a primary motivator.

What writings from ancient times are you thinking of, that treat this as a serious issue for consideration? — andrewk

The Cyrenaics on perceptual relativity, which they took to mean that we can only have knowledge of our perceptual awareness, and not what caused it. Also, the bent stick in the water and other optical illusions were pointed out by Greek skeptics.

And Indian philosophical tradition has been influenced by meditative states and the idea that the world we perceive is an illusion generated by mistakenly thinking we are separate beings.

"Seeing mental images" is indeed a "spectre"; we never see any such thing. We see real or imagined trees. — Janus

I expressed it as "experiencing seeing mental images", which does happen in dreams, imagination, memory and hallucination. In a dream in particular, the experience is as if wee saw a tree with our eyes. It might not be so vivid in imagination, depending on one's capacity for visualization, but I can certainly imagine myself looking at a tree.

Is this affection or process direct or indirect? I would say the question could be answered either way depending on how I think about it; there is no inherent contradiction between these two ways of answering . the contradiction only arises if I demand that one of then must be right. must be absolute; whereas both are only interpretive ways of thinking about experience. — Janus

That might be so, but the long standing concern is ancient skepticism, where we're cut off from knowing about the actual objects that caused the perception. Can interpreting experience in different ways alleviate this concern?

It is a problem of grammar or vocabulary, rather than philosophy. — andrewk

Nah, if the problem of perception were trivially a misuse of words, it wouldn't have persisted for several millennia. Someone back in Ancient Greece, China or India would have pointed it out, and that would be the end of that.

Also, it wouldn't have survived the linguistic and cultural transitions from then until now, since different ways of expressing the problem would have shown that it was a mere grammar mistake.

At least, I don't think it would have taken all the way to Wittgenstein to notice the problem. If it's that hard to figure out, then something else is going on.

This seems straightforward to me, so I can't see where the concern lies. If the above doesn't alleviate your concern, could you please elaborate on what you are concerned about? — andrewk

Whether perception is direct or indirect via a mental intermediary. Dreams, hallucinations, etc bring up the possibility that perception involves an idea in the mind that we experience instead of the public tree.

That we can distinguish dreams, hallucinations, etc from perception is of no pragmatic help here.

I'm not advocating for dream skepticism, and I recognize that we can differentiate our kinds of experiences, such that we know when we have a perception.

The issue for direct realism is that we do have visual (and other sensory) experiences independent of perception. This raises the spectre that perception involves a mental intermediary instead of being direct.

I bring up dreams, imagination, etc for that reason, but usually it's just hallucinations.

The problem is that my experience of a dream tree is similar to an experience of perceiving a tree. So while you can say we don't see or hear when we dream, we do have experiences of seeing and hearing.

The same thing happens when you daydream, except that it's under conscious control. The question that arises is if I can experience seeing when not using my eyes, then what is that I experience when using my eyes?

That's why hallucination is one of the things trotted out against direct realism, because it demonstrates that sometimes we do behold a mental construct, so how do we know that it's not always the case that we're experiencing a mental construct?

Or we can be pragmatic while we do philosophy, as the American Pragmatists, amongst others, did. — andrewk

I understand that. But how does philosophical pragmatism help with concerns raised by noting that dream or hallucination experiences can be like perceptual ones?

If pragmatism deals with those concerns by dismissing them on pragmatic grounds that we can distinguish between experiences, then that's no different from what we do in everyday normal life. It's basically a shrug at the philosophical question being raised.

It will be pissed when it wakes up from that dream in turn and discovers it is a figment of the Matrix. All it sees is magnetic 1s and 0s. And now the Google lab guys are reaching for the reset button to .... argh! — apokrisis

Is that when it launches the nukes and starts making terminators?

Computer scientists can be a very different matter. To the degree they haven't studied biological science, they are liable to claim just about anything of their toy machines. — apokrisis

Breakthrough in Google's DeepMind:

Last night it dreamed it was a butterfly, and then awoke, wondering if it was a butterfly dreaming.

EDIT:

Should substitute cat for butterfly, and videotaping for dreaming.

Are there any cognitive neuroscientists or psychologists who could be direct realists? The only one that springs to mind is James Gibson. — apokrisis

That has to be taken with a grain of salt, because it depends on how familiar a scientist is with the philosophical arguments. Sometimes a scientist will publicly articulate a philosophical position that's not terribly sophisticated, but they act as if the science backs it, because they don't know the depth of the philosophical discussion on the matter.

Accuracy is reimagined as successful adaptation. Truths are word-tools that work. What is it to work? There we move into the realm of feeling and ineffability. — t0m

That's interesting. But that it can't answer why the word-tools work means that philosophical questions remain. Maybe Witty relegated that to the mystical. I understand the appeal of that.

Let's take the example of minds, dreams, perceptions. On a pragmatic account, they do a pretty good job of determining truths like whether the tree is a threat to my house. But they leave open the question of whether my experience of the world is all there is.

I think they naturally occur. But then a sophisticated tradition emerges. Would you agree that metaphysics can become a clever game? — t0m

Yeah, sure.

If I may rewind: let's say your OP is 'really' about what is good or virtuous. — t0m

It's not. I just mentioned the Cyrenaics as an example of people who acted on their metaphysical conclusions.

It's more similar to mathematical questions such as whether P=NP or not.

If we can't be reasonably sure that our perceptions are of external objects, then we have nothing to base our empirical knowledge on. And we have no justification for other minds.

Then metaphysicians rip these tools out of context and try to do eternal super-science with them... — t0m

Did these questions originate with metaphysicians, or are they ones that naturally occur to human beings upon reflection?

So are you a data stream within a data stream?

Both Marchesk and creative soul are data streams in my brain, as is the sensation from my fingers as I type. — charleton

Is your brain also a data stream?

There are pragmatic differences between those situations that are easy to characterise. — andrewk

The pragmatic differences is what led to the philosophical questions. We can all be pragmatic and ignore philosophy if we want. But some of us don't want to.

What does it mean to say that "we behold a mental construct"? — t0m

It means that perception is experienced inside our minds, just like the case with dreams.

How is this "cashed out" in action? If we somehow knew that is was true, then how would we behave differently?

Well, there was a philosophical school in Ancient Greece called the Cyrenaics who built up an entire way of life based on following through with perception being mental. If we don't have access to external objects, then only our bodily sensations matter, and thus, pleasure is the only good.

I'm suggesting that we trace fuzzy distinctions back to the practical concern that employs them. (In short: pragmatism.) — t0m

But metaphysical questions aren't concerned with being pragmatic. If you want to be pragmatic, then everyday common sense and science are enough. But some human beings like to ask questions about the nature of our existence, what we can know, etc.

That's a really good answer, Apo. But direct realists would make an exception for veridical perception and say that it's one way information flow from the senses to the brain. That's what makes it veridical (that and the causal history from light bouncing off tree into eyes).

The reason the language game answer doesn't work for this is because the difference between a dream tree and a perceived tree matters a great deal. If I dream of a tree falling on my house, but upon wakening, realize there is no tree near the house, then I forget about it.

But if perceive a tree looking like it might fall on my house, then I will take action. Similar with hallucinations. If I hallucinate an intruder in my house, then I'm not in any danger. But if I perceive one, then it's time to call the police.

What this points out is that there is a fundamental difference between experiences. Some of them are mental. They are generated only by my mind. And some are public. The police can show up and find evidence of an intruder. Other people can perceive the same things I do.

Public experience is objective, and that allows us to do science, to agree on language games, and so on. There is a reason that we developed objective methods for inquiry. And there's a reason science disregards subjective experience. My dream of being abducted is not evidence for the existence of aliens.

So when philosophers debate whether we have direct access to public objects, they're concerned about issues like skepticism. If there is a veil of perception between us and the world, then how doe we know it's there? Maybe other people are just dream people, etc.

If you really do exist as a 'experience-orb' there's just no way of knowing if there really is a tree (or more importantly, other orbs) out there beyond your experience. — antinatalautist

Well, what happens when a tree falls on you and no other orbs are around to experience it? Does your experience end? Let's say you didn't even notice the tree. It's not real to you or anyone else. Do you still die?

That's the problem with idealism. It's absurd, because it creates a gappy world between experience that still somehow affects who gets to experience what. So some other experience orb will find your squished body and realize a tree fell on you. If nobody experienced the tree, then why did your experience orb come to an end?

I stated that without the concept or idea of what a tree is, there is/may be no tree. — Cavacava

Okay, but then what happens when you decide to run through the unconceptualized blob of green & brown?

So, when looking at a tree, are you aware of the tree or your mental representation of it. — Harry Hindu

I'm aware of the tree.

It's like asking, "Are you aware of the word, or what the word refers to?" They are both separate things that are linked together by representation. Because it is a representation, you could say that by being aware of one as a representation, then you are aware of what it represents. — Harry Hindu

But then what does a dream tree represent?

Ah, the infamous duck-rabbit. Banno would be proud. It's interesting, but the thing is if you had never heard of a rabbit before, and you saw one, you wouldn't confuse it for a duck. You would just think it was some cute, furry mammal with big ears that hops around, and then ask people what it was.

This is because whether something is mental or not depends on context. — Magnus Anderson

The worry is that if see a mental image while perceiving a tree, then how do we know there is a tree at all? It could be just like a dream tree. That naturally lends itself to skepticism, where the context is undermined by holding all of perception in doubt.

So is perception of a tree... phenomenological given and therefore we play a passive role or is the tree a representation which we actively construct, and are responsible for? — Cavacava

I don't have much control over seeing a tree. Maybe some drugs and meditative exercises would help me see it in some other manner?

I would say perception is given.

How do you square it? — apokrisis

Pun intended?

I agree that this is an attractive position to take, But it is fundamentally inconsistent. — apokrisis

The reason is because color is likely creature dependent, while shape is not. Shape is objective, and doesn't depend on the kind of eyes we have.

But you're wondering how perception can involve awareness of both mental and non-mental properties of an object. That is a good question.

ut I've yet to see anything that suggests there is any difference between 'being conscious of a mental tree' and 'being conscious of a tree itself', beyond the differences in the strings of letters that make up the two phrases. — andrewk

So you see no difference in meaning between dreaming of a tree, remembering a tree, visualizing a tree, hallucinating a tree, and perceiving a tree?

Fine. Answer that version of the same question then. — apokrisis

I don't know. What makes perception qualitatively different from other mental experiences? It is remarkable how much a dream seems like you're perceiving. The disjunctivists deny that the experiences are the same. I'm not sold on that.