It talks about "different individuals view[ing] the same image ... reported it to be widely different colors" and "different individuals experienc[ing] different percepts when observing the same image of the dress".

Different percepts entail different reported colours because color nouns ordinarily refer to those percepts, not the light emitted by the computer screen.

It is a fact that I see white and gold and others see black and blue because it is a fact that I experience white and gold percepts and others experience black and blue percepts.

Ugh... the "some see white, others see black" is philosophical spaghetti. — frank

No, it's a scientific fact. There's a whole bunch of studies on the matter, such as Exploring the Determinants of Color Perception Using Thedress and Its Variants: The Role of Spatio-Chromatic Context, Chromatic Illumination, and Material–Light Interaction.

You seem to be letting some armchair philosophy (Wittgenstein?) get in the way of empirical evidence.

If you're going open the door to questioning inherent beliefs, then why arbitrarily limit it? — Hanover

It's not arbitrary. I've just read up on some physics and neuroscience of perception. Atoms are mind-independent objects with mind-independent properties; their electrons absorb and re-emit various wavelengths of light, this light stimulates the rods and cones in the eyes, the eyes send signals to the brain, the neurons in the visual cortex are activated, giving rise to visual percepts, including colour percepts.

Those who see a white and gold dress have different colour percepts to those who see a black and blue dress, because different neurons in the visual cortex are activated.

I don't understand the aversion to what I am saying. Do you object to me saying that pain is a mental percept, not a mind-independent property of fire?

The word "experiences" refers to experiences, so why can't the word "colours" refer to a subset of experiences?

And again, the use of the nouns "white", "gold", "black", and "blue" in the sentence "some see white and gold, others black and blue" when describing the photo of the dress is referring to differences in colour experiences, not differences in the computer screen's micro-structural properties or light emissions.

Do you agree or disagree?

If it's 1, then color language can refer to both subjective and objective accounts. — frank

I haven't denied this. I've only argued that our ordinary, everyday understanding of colours is an understanding of colour experiences, not an understanding of atoms absorbing and re-emitting various wavelengths of light, and that our ordinary, everyday use of colour nouns refers to these colour experiences.

The use of the nouns "white", "gold", "black", and "blue" in the sentence "some see white and gold, others black and blue" when describing the photo of the dress is the ordinary, everyday use and is referring to differences in colour experiences, not differences in the computer screen's micro-structural properties or reflectances.

We just happen to naively and unreflectingly think of these colour experiences as being mind-independent properties of distal objects rather than mental percepts. And we're welcome to think of and talk about the world in that way if we like (and we often do), but we'd be wrong.

That depends on what you mean by "know". If you mean certainty, then sure; we can't know what each person is experiencing. If you mean a true, justified belief, then we might know what each person is experiencing, e.g. if their experiences are in fact similar to our own. And again, given our similar biologies it stands to reason that our experiences are mostly similar.

I don't understand what you mean. Is there a "standard" pain? A "standard" pleasure? A "standard" sour taste?

He or she is saying that since this uncertainty exists, we have to conclude that color experiences are unique to each individual. — frank

We certainly have evidence that colour experiences can differ between individuals; the dress is the obvious example, but also differences in color categorization manifested by males and females.

And speaking for myself, my left eye sees a slightly different colour (or hue) than my right eye.

But given that the macroscopic world is deterministic, and given that we have mostly the same kind of eyes and brains, it stands to reason that our colour experiences are broadly similar in most cases.

Referring to the SEP article you referenced before:

There is a group of views about color, which come under one or all of the labels, Color Irrealism, Color Eliminativism, Color Fictionalism. These titles are a little misleading, since some theorists also talk of there being colors in the sense of being dispositions to cause experiences of a characteristic type, and/or being (attributes in/of) sensations. Following our earlier discussion, in section 1.2, we may take it that what the color-Eliminativist is denying is that material objects and lights have colors of a certain kind: colors that we ordinarily and unreflectingly take the bodies to have.

...

Color Primitivist Realism is the view that there are in nature colors, as ordinarily understood, i.e., colors are simple intrinsic, non-relational, non-reducible, qualitative properties. They are qualitative features of the sort that stand in the characteristic relations of similarity and difference that mark the colors; they are not micro-structural properties or reflectances, or anything of the sort.

Our ordinary conception of colours is that colours are "simple intrinsic, non-relational, non-reducible, qualitative properties ... not micro-structural properties or reflectances".

The naive (color primitivist) realist falsely believes that these colours are mind-independent properties of objects, when in fact they are mental percepts.

This does not deny that we can use the adjective "red" to describe objects with certain micro-structural properties or reflectances; it only states that micro-structural properties or reflectances are not how we ordinarily understand colours, and not what we ordinarily refer to when we use the nouns "red" and "colour".

'Red' refers to an object's disposition to cause certain colour experiences. — jkop

The word "red" can be used to refer to an object's disposition to cause certain colour experiences, but they ordinarily refer to those certain colour experiences. Those colour experiences are what we ordinarily understand by colours, especially before we have any understanding of an object having a surface layer of atoms that reflects certain wavelengths of light.

When I think about the colour red, I think about the colour experience, not atoms reflecting light. When we describe the fact that some see a white and gold dress and others a black and blue dress, we are describing differences in colour experiences, not differences in objects reflecting light.

The words "white and gold" and "blue and black" are referring to both, the light being emitted by the dress and perceived by the viewer. — creativesoul

They aren't referring to both. When my colleague and I look at the photo of the dress we see different colours. The noun "colours" isn't referring to the light because we don't see different light; it's referring to our visual percepts, which are different.

This is the ordinary use of the noun, and what we ordinarily understand colours to be (and what the naive realist mistakes to be a mind-independent property of things). That we then might use the adjective "coloured" to describe the computer screen does not change this. Much like the noun "pain" refers to the mental percept even though the adjective "painful" describes things like stubbing one's toe.

"Visual percepts" is again hollow. It means the patient discerned shapes. "Visual percepts" is hypostatisation. — Banno

"Visual percepts" is standard terminology in the neuroscience of perception.

See visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex.

That sometimes one person sees blue where the other sees gold does not change this. — Banno

The nouns "blue" and "gold" in this sentence are referring to percepts. We see the same screen, we see the same light, but we don't see the same colours. Therefore the colours we see are not mind-independent properties of the screen or the light.

And the way the nouns "blue" and "gold" are being used in this sentence is the ordinary use of the word, and the things they refer to are what we ordinarily understand to be colours.

What he doesn't understand: you can't have a first premise (reality exists) and then from this premise prove that the premise is wrong. That's not a valid argument. — Gregory

Yes you can; it's called refutation by contradiction.

It's not even a philosophical issue; it's a scientific issue. And the neuroscience shows us that visual percepts exist when there is neural activity in the visual cortex.

Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex.

Your explanation of what causes variations in colour perception is not relevant to the claim I am making.

I see white and gold when I look at the photo of the dress. The nouns "white" and "gold" in the preceding sentence do not refer to the screen's "disposition" to emit the wavelengths of light typically associated with white and gold; they refer to the types of mental percepts that I have and that those who see black and blue don't have.

Two people looking at the same photo on the same screen can see different colours. See the dress.

I see white and gold, my colleague in the same room looking at the same screen sees black and blue.

The nouns "white", "gold", "black", and "blue" in the preceding sentence are referring to percepts, not mind-independent properties of the screen or the light. This is the ordinary use of such nouns.

See also variations in colour perception.

Maybe quote the rest of the sentence:

When I look at the photo of the dress and describe its colours as white and gold, the words “white” and “gold” are referring to colour percepts, not the pixels on the screen emitting certain wavelengths of light

Do you agree or disagree with this?

When looking at the photo of the dress, some see white and gold, some black and blue. This is a fact. What are the words "white", "gold", "black", and "blue" referring to in that sentence?

I say mental percepts.

Six months later, Michale is still here to argue that he is most probably a Boltzmann brain — Banno

I'm not arguing that here. I'm simply responding to the question asking if brains can generate experiences in the vacuum of space. The Boltzmann brain thought experiment shows that such a scenario is both coherent and consistent with current scientific theories.

When one has an experience, it is an experience of something. When there is no "something", it's an hallucination. — Banno

You seem to be using "experience" to mean "veridical experience". You're welcome to, but that's not what is meant when discussing Boltzmann brains.

As an example, taken from Wikipedia:

Experience refers to conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these processes. Understood as a conscious event in the widest sense, experience involves a subject to which various items are presented. In this sense, seeing a yellow bird on a branch presents the subject with the objects "bird" and "branch", the relation between them and the property "yellow". Unreal items may be included as well, which happens when experiencing hallucinations or dreams.

When I talk about experience I mean any occurrence of visual or auditory or other percepts, produced by activity in the visual or auditory or other cortexes, regardless of what caused it. The experience is veridical if it is caused by the appropriate external stimulus, a dream if asleep, or an hallucination or illusion otherwise.

The colours in the photograph are susceptible to blend and interfere with changing light conditions on different screens and environments where the photo is displayed. Basically we don't just see the colours of the dress, but a blend of its colours with the colours from different environments or screens, and that's why different observers tend to see different colours. — jkop

We look at the same distal object (the pixels on the screen), our eyes react to the same proximal stimulus (the light), and yet we see different colours. Therefore, the noun "colours" in the preceding sentence is not referring to some property of the distal object or some property of the proximal stimulus; it is referring to the type of mental percepts that differ between individuals.

And the way we're using the noun "colours" in that initial sentence is the ordinary use of the word.

That's plainly false. Red paint really reflects wavelengths of 700 nm, and to experience it as red is to have a veridical experience of it (unlike experiencing 700 nm as gray (if colorblind) or as any colour, sound, smell etc. (if hallucinating). — jkop

You're putting the cart before the horse. Light with a wavelength of 700nm ordinarily causes red colour percepts in most humans, and so we use the adjective "red" to describe objects which reflect light with a wavelength of 700nm.

But as a noun, the word "red" ordinarily refers to that type of percept.

Historically, before we knew what these percepts were, we mistook them for being mind-independent properties of objects. This is the naive realist view. We know better now.

So you're denying the existence of dreams, hallucinations, synaesthesia, variations in colour perception, and basically the entire neuroscience of perception.

Well, you're welcome to, but you're wrong.

There is no practical reason to refer to "mental percepts" at all, or for that matter — Richard B

Yes there is; to make sense of dreams, hallucinations, synesthesia, variations in colour perception (e.g. the colours of the dress are white and gold to some and black and blue for others), and visual cortical prostheses.

And these mental percepts exist in ordinary waking experiences to. They are what we ordinarily refer to when we use colour nouns, knowingly or not. An object reflecting various wavelengths of light is just the ordinary cause, nothing more.

How do we perceive this propensity? — Hanover

How do we perceive a fire’s propensity to cause pain? By putting our hand in the fire and being hurt. In the case of colour, we look at the pen and see red.

Do we just assume our perceptions are externally caused? — Hanover

I think it’s a little more than an assumption. Perhaps it’s the most rationally justified explanation.

Since all perceptions are subjective responses, you can't claim any property to exist objectively, except to just say the perceptions must be being elicited by something. — Hanover

We can claim anything we like. Some are true, some are false, and some may be more justified than others.

I think it’s justified to claim that mind-independent chairs exist but that mind-independent pain doesn’t, and most would agree. Clearly there’s just less of a consensus regarding whether or not colours are more like chairs or more like pain. I think modern physics and the neuroscience of perception shows them to be more like pain.

That is, an atom has no particular shape, size or color. It just makes me see what I think to be a chair. — Hanover

That would certainly be the Kantian view, and I’m sympathetic. But I’m not arguing for anything that extreme. I’m only arguing that colours, like pain, are a mental percept.

Yet, I can see black objects. I can pick out an object that is black from other objects that are colored. Why can't we say it lacks the property of color? What makes less sense is to say I pick out a black object because it has no mental percepts. I pick it out because it was black. — Richard B

I have repeatedly drawn a distinction between the adjective “red” and the noun “red”.

We can use the adjective “red” to describe a mind-independent pen that has properties that are the cause of red colour percepts. But the noun “red” refers to that colour percept, not a mind-independent property of the pen.

If you don't distinguish between experience (i.e. event in your brain) and colour (i.e. object of the experience), then you can't distinguish between veridical experiences and hallucinations. How could any animal have survived on this planet if they were only hallucinating and never saw objects and states of affairs? Arguments from illusion or hallucination suck. — jkop

In the case of colour there is no such thing as veridical. It’s not “correct” that light with a wavelength of 700nm causes red colour percepts, such that if a different organism with different eyes and brain sees a different colour in response to 700nm light then they are seeing the “wrong” colour.

I didn't say that. I said that the pigment and the light have the disposition to systematically cause the experience of colour. This means that the colour experience arises when an animal that has the ability sees the pigment or light, while the colour is a property of the pigment or light in the form of a disposition. — jkop

We can use colour terms however we like, but when we ordinarily use them we are referring to colour percepts, not an object’s disposition to reflect a certain wavelength of light.

When I look at the photo of the dress and describe its colours as white and gold, the words “white” and “gold” are referring to colour percepts, not the pixels on the screen emitting certain wavelengths of light, and when someone else looks at that same photo and describes its colours as black and blue, the words “black” and “blue” are referring to colour percepts, not the pixels on the screen emitting certain wavelengths of light.

If the words “white”, “gold”, “black”, and “blue” were referring to the pixels on the screen then the very claim that some see white and gold and others see black and blue (when looking at the same screen) would make no sense at all. Yet it is both coherent and factual.

Things are black when they absorb all (visible) frequencies of light, and so do not re-emit any (visible) frequency of light.

As such there is no (visible) light to stimulate the rods and cones in our eyes, and so the V4 neurons are not fired, and so no colour percepts are produced.

It’s certainly not the case that black is some mind-independent property of objects that is seen by the absence of (visible) light. That just makes no sense at all.

the colour that you experience exists regardless of being experienced — jkop

The surface layer of atoms with a configuration of electrons that absorbs certain wavelengths of light and re-emits others exists regardless of being experienced.

But this isn’t colour. Colour is the mental percept created by neural activity in the visual cortex. That is how coloured dreams, coloured hallucinations, synesthesia, and variations in colour perception are possible.

Referring to mind-independent objects as having colours is a relic of naive colour realism, the mistaken view that either confuses colour percepts for being mind-independent properties or falsely believes that, in the veridical case, colour percepts resemble mind-independent properties. Our modern scientific understanding of the world and perception has corrected us of this misunderstanding.

It is just "physical system capable of producing consciousness." — Count Timothy von Icarus

Such as a brain:

The scenario initially involved only a single brain with false memories, but physicist Sean M. Carroll pointed out that, in a fluctuating universe, the scenario works just as well with entire bodies, even entire galaxies.

…

… human brains are vastly more likely to arise from random fluctuation …

…

Boltzmann-style thought experiments generally focus on structures like human brains that are presumably self-aware observers.

Although this seems to be moving beyond the relevant point, which is that colour percepts are the product of neural activity in the visual cortex. This neural activity can be caused by optical stimulation by light, e.g. when awake, or by other things, e.g. when hallucinating or dreaming. We don’t need to posit some additional mind-independent colour; we already have a parsimonious account of colour perception consistent with the scientific evidence.

Are you under the impression that Boltzmann brains actually exist? — Count Timothy von Icarus

No, I’m saying that they are a coherent concept and consistent with current scientific understanding.

Weird that a chameleon would change my mental phenomena(the color of the chameleon) and result in blending into its surroundings which are not my mental phenomena. — creativesoul

They change the way their skin reflects light. Different wavelengths of light elicit different colour percepts.

You asked if brains can generate experiences in the vacuum of space. Boltzmann brains are formed in the vacuum of space, and “in Boltzmann brain scenarios … Boltzmann observers who have the same series of experiences as me … vastly outnumber normal observers.”

So, yes, apparently brains can generate experiences in the vacuum of space. All that is required is the appropriate neural activity, regardless of what causes and maintains it.

Does a brain generate any experience on the ocean floor? On the surface of a star? In the void of space? — Count Timothy von Icarus

You should read up on Boltzmann brains.

But why? — Banno

We talk about various things in the world. Some of those things are mental phenomena, some aren't. Some of those things are trees, some aren't. I don't understand the difficulty you're having.

Your question is like asking why the noun “dog” picks out an animal and not a planet.

In addition to what? — Banno

As in, among the various types of mental phenomena, colour is one such type.

Why shouldn't a red pen simply be a pen that reflects light at various wavelengths and various intensities? — Banno

You can use the adjective "red" to mean "reflects light with a wavelength of 700nm" if you like, but when we ordinarily talk about colours (note that I'm now using a noun) – particularly when we ask if colours are mind-independent and discuss the fact that some see white and gold and others black and blue – we are talking about colour percepts, knowingly or not.

And there’s certainly no “resemblance” between a red colour percept and a surface layer of atoms that reflects light with a wavelength of 700nm. The relationship between the two is merely causal, and that the latter causes the former is a contingent fact about human biology. Different organisms with different eyes and brains can have different colour percepts in response to 700nm light. The photo of the dress is proof of that even within humans.

How come "pen" picks out a mind-independent object, and not just whatever has the causal role in eliciting a particular type of mental percept. Doesn't the noun "pen" refer to this type of mental percept? — Banno

Because some words pick out mental phenomena and some words don't? Even the naive realist must accept this; words like "mind", "consciousness", "pain", "pleasure", "beliefs", "disgust", and so on pick out mental phenomena.

I am simply explaining that colours are also a type of mental phenomena, not a type of mind-independent property of pens. As I said to Richard B above, the pen just reflects light at various wavelengths and various intensities and then our eyes and brain respond in deterministic ways to this electromagnetic energy, activating the visual cortex and producing visual percepts (including colour percepts).

The naive view that projects these colour percepts onto mind-independent objects, or that thinks that some mind-independent property "resembles" these colour percepts, is mistaken.

The noun "pen" refers to a mind-independent object. The adjective "red" describes this mind-independent object's causal role in eliciting a particular type of mental percept. The noun "red" refers to this type of mental percept.

I think I've been really clear on this.

In this example, are the contact lenses causing new mental phenomena? — Richard B

Yes.

Or, are they just allowing us to see the colors the fruit had all the time. — Richard B

The fruit just reflects light at various wavelengths and various intensities; that's it. Our eyes and brain then respond in deterministic ways to this electromagnetic energy, activating the visual cortex and producing visual percepts (including colour percepts).

For example, a person took a hallucinogen which put the brain in a particular physical state, and thus caused the hallucination. Is this not enough to explain what is happening without appeal to mental phenomena? — Richard B

I haven't said that mental phenomena aren't just particular brain states. I'm not necessarily arguing for any kind of dualism. I'm leaving that open. Maybe pain just is the firing of C-fibers, as Churchland argues. Maybe colours just are the firing of V4 neurons.

Regardless of what mental phenomena are, pain and colours are mental phenomena; they are not mind-independent properties of fire.

on your account we are talking not about the red pen but each of our own solipsistic percept-of-red-pens — Banno

No I'm not.

So on your account, when we agree that the pen is red, we are talking about quite different things - the percept-in-my-mind and the percept-in-your-mind. — Banno

No, because we're using "red" as an adjective to describe the mind-independent pen.

We all agree that this pen is red (causes red mental percepts), just as we all agree that stubbing one's toe is painful (causes pain mental percepts).

But "red" and "pain" as nouns refer to mental percepts, not to some mind-independent property of pens.

Of course, this is generally presented as the squares themselves being "the same color." You can confirm this by looking at the hex codes of the pixels that make them up.However, on an account where grayness, shade, hue, brightness, etc. are all purely internal and "exist only as we experience them," it seems hard to explain the illusion. If the shades of gray appear different, and color just is "how things appear to us," in what sense are the two squares the "same color gray?" It seems that their color should rather change with their context. — Count Timothy von Icarus

They emit the same wavelength of light, but produce different colour percepts. It's the same principle involved with the photo of the dress.

Colour terms like "grey", "black", "blue", "white", and "gold" are then used in at least two different ways, either referring to the fact that they emit the same frequency of light ("the squares are the same shade of grey") or to the fact that they produce different colour percepts ("I see white and gold; she sees black and blue").

The use of such terms to refer to the fact that they emit the same frequency of light is something of a fiction, premised on the misguided naive realist view that treats colour percepts as being mind-independent properties (or, at the very least, the misguided view that colour percepts "resemble" in some sense mind-independent properties).

You said that movies cannot be funny, the lemons are not sour, and that apples cannot be red. — Count Timothy von Icarus

I clarified what I meant in that aforementioned post.

The nouns "sour" and "red" refer to mental percepts – those things that also exist when we dream, hallucinate, have synesthesia, and so on, and which explain differences in perception.

The adjectives "sour" and "red" when predicated of lemons and apples describe the fact that they are causally responsible for the associated mental percept in ordinary waking situations.

So apples are red and lemons are sour.

But this doesn't mean that redness and sourness are mind-independent properties of apples and lemons as the naive realist believes.

Pace your appeal to "science," the science of perception does not exclude lemons from an explanation of why lemons taste sour or apples from the experience of seeing a red apple. These objects are involved in these perceptions; the perceptions would not exist without the objects. — Count Timothy von Icarus

Their involvement is causal, nothing more. The window wouldn't have broken if the football had not been kicked through it, but the broken window is not a property of the football. And the sour-taste mental percept would not be present if I had not eaten the lemon, but the sour-taste mental percept is not a property of the lemon (and nor does it resemble any of the lemon's properties).

How exactly does your account even allow for the coherence of dreams, hallucinations, synesthesia, and difference in colour perception, let alone their facticity?

I think you're misunderstanding my position. Here and here set it out clearly.