If a Rose Falls in the Forest and No One Sees It, Is It Still Red?
If a rose falls in a forest with no observer, can it meaningfully be said to be “red”? This paper explores this question by integrating perspectives from physics, neuroscience, psychology, and philosophy of perception. We distinguish the physical basis of color (light wavelengths and surface reflectance) from the perceptual experience of color in the brain. Key concepts from color theory are reviewed, including how objects produce color through selective reflection and absorption of light, and how the human visual system creates color experiences only when light stimulates retinal photoreceptors. We discuss how different mixtures of light (monochromatic versus polychromatic) can appear identical, underscoring that color is determined by the observer’s sensory processing. The opponent-process theory of vision and phenomena such as afterimages demonstrate the brain’s active construction of color, even in absence of corresponding wavelengths. Philosophical implications are examined: many thinkers argue that color is a subjective or relational property that does not exist independently of perceivers. The central claim is supported by scientific and philosophical evidence – if no one (and no sensory apparatus) is there to detect certain wavelengths, no color experience arises. In that sense, an unseen rose is not “red” as color is ultimately a product of perception rather than an intrinsic property of the rose.
Introduction
Is color a property of the external world or a product of our minds? The question “If a rose falls in the forest and no one sees it, is it still red?” echoes the classic philosophical riddle about a tree falling unheard in the woods. It invites us to consider whether color – in this case, the red of a rose – exists independently of any observer. This issue bridges multiple disciplines. Philosophers of perception have long debated whether color is part of objective reality or a subjective construct. Physicists and photographers deal with the behavior of light and surfaces, understanding that what we call “color” originates in the wavelengths of light an object reflects. Neuroscientists and cognitive psychologists study how the eyes and brain translate those wavelengths into the vivid experiences of color we know. Artists grapple with color in practice, manipulating light and pigment to evoke certain perceptions. An interdisciplinary examination can thus enrich our understanding of what it means to say an object “is red.”
Historically, leading thinkers have been skeptical that color resides in objects at all. As early as the 17th century, Galileo Galilei argued that qualities like color are not inherent in material objects but exist only in consciousness – “if the living creatures were removed, all these qualities would be wiped away and annihilated”. David Hume similarly noted that “colors, heat and cold… are not qualities in objects, but perceptions in the mind”. Physicists from Isaac Newton to James Clerk Maxwell agreed that color is fundamentally a sensation produced in the observer. For example, Newton wrote that light rays themselves are not colored, but have a “certain power and disposition to stir up a sensation of this Colour or that” in us. Such statements suggest a distinction between the physical aspect of color (light of certain wavelengths, reflectance properties of objects) and the perceptual aspect (the experience of color in a seeing subject).
This paper will explore that distinction in detail. We begin by outlining the nature of color from both a physics and a perception standpoint, clarifying the difference between wavelength and color experience. We then describe the physics of light–object interactions: how a rose’s petals reflect certain wavelengths to produce the potential for “red.” Next, we examine human vision and neural processing: how only when light enters the eye and stimulates photoreceptors does the brain generate a color sensation. We discuss color mixture and metamerism – cases where different physical light compositions yield the same perceived color – to underscore the role of the observer’s visual system. We then turn to the opponent-process theory and visual afterimages, which show the brain can create colors internally even without external input, reinforcing the idea that color depends on neural processes. Finally, we consider the philosophical implications: does color exist independently of perception or is it solely a construct of the observer? Throughout, we support the central claim that if no one (no visual system) sees light at certain wavelengths, then “red” as a color is never realized – the unseen rose is not red in the usual sense of color.
The Nature of Color: Physical Wavelengths vs. Perceived Color
Color can be understood in two related but distinct ways. Physically, color corresponds to certain wavelengths (or combinations of wavelengths) of electromagnetic radiation in the visible spectrum. For example, light with a wavelength around 650–700 nanometers is typically labeled “red” light. Perceptually, however, color is the experience that arises when those light stimuli interact with an eye and brain. The key distinction is that wavelengths themselves are objective and exist whether or not anyone is present, whereas the perception of redness is a subjective experience that occurs only in a viewer. In everyday language we often conflate these, saying “red light” or “a red rose” as if color were an intrinsic property of light or objects. Scientifically and philosophically, it is important to separate the stimulus from the sensation.
We know from color science that objects and lights have certain physical properties (spectral distributions of light), but those are not identical to the colors we see. As vision researcher Stephen Palmer explains, “neither objects nor lights are actually ‘colored’ in anything like the way we experience them. Rather, color is a psychological property of our visual experiences… based on physical properties of objects and lights that cause us to see them as colored”. In other words, an object’s surface may reflect light predominantly in the red portion of the spectrum, but the red we perceive is a construction of our visual system in response to that stimulus. Modern color theory thus treats color as an interaction between physical stimuli and a perceiving observer. Philosophers describe color (along with tastes, sounds, etc.) as a “secondary quality” – a quality that arises only in the presence of a perceiver’s senses, in contrast to “primary qualities” like shape or mass which exist in the object itself. From this perspective, saying “the rose is red” is shorthand for saying it has the physical properties that would cause a normal observer to experience red under suitable conditions. If no observer ever experiences it, one can argue that “redness” as such does not manifest. There may be light of 650 nm emanating from the rose, but color in the full sense – as a sensation or appearance – requires an eye and a brain.
At the same time, it is understandable why we intuitively treat color as a property of objects. In everyday experience, we consistently see a rose as red, grass as green, the sky as blue, and we rely on those stable appearances to identify and describe things. The stability of color under common conditions gives the impression that color is a fixed attribute “out there.” However, even everyday observations hint that color is not fixed in the object: a rose at night under moonlight loses its redness (appearing nearly gray), and that same rose under a reddish sunset may look different than under noon sunlight. The “real color” seems to shift with lighting, pointing to the fact that color involves the illumination and the observer’s perception, not just the object alone. Additionally, different observers can perceive color slightly differently (consider colorblind individuals, or even how a camera sensor “sees” colors versus a human eye), which again suggests color is a relation between object and perceiver.
In summary, color has a dual character: it is rooted in physical reality (wavelengths of light, reflectance spectra) but realized only through perceptual processes. To further explore the “physical” side, we next examine how the physics of light and the rose’s properties generate the stimuli for color. Then we will delve into how the human visual system picks up those stimuli and produces the experience of red – a necessary step for the rose to be “red” in any meaningful sense.
The Physics of Light and Color: Reflection and Absorption
From a physics perspective, color is fundamentally about light – specifically, visible light, which is electromagnetic radiation in the wavelength range of roughly 380 to 750 nanometers. Objects do not generate color on their own; instead, they affect the light that falls on them. The appearance of a colored object arises from a combination of the spectrum of the incident light and the object’s material properties (which wavelengths it absorbs vs. reflects or transmits). In simple terms, an object’s color is determined by which wavelengths of light it reflects to the observer’s eyes and which it absorbs. If an object reflects predominantly longer wavelengths (~620 nm and above) and absorbs others, it will likely appear red to a human observer under white light. If it reflects mostly shorter wavelengths (~450 nm), it will appear blue, and so on.
A red rose provides a clear example. Sunlight (or white light) contains a mix of all visible wavelengths. When sunlight hits the rose’s petals, the pigments in the petals (such as anthocyanins) absorb a significant portion of the blue and green wavelengths and preferentially reflect the longer red wavelengths. Thus, the light that bounces off the rose and reaches an observer is enriched in the red end of the spectrum. The rose appears red because it is reflecting those red-band wavelengths into our eyes while absorbing the rest. Importantly, the color is not “in” the rose independently – it is in the combination of the rose’s reflectance properties and the illumination. As a physics tutorial notes: “The color of an object is not actually within the object itself. Rather, the color is in the light that shines upon it and is ultimately reflected or transmitted to our eyes”. In total darkness, the rose has the same molecular structure, but without light there is no reflected wavelength to be seen – the rose looks black (no color) because no light reaches the eye. And if the illuminating light is changed, the rose’s appearance changes: under a pure blue light, a red rose would reflect very little (since it cannot reflect what it does not receive) and thus might look nearly black or dull, illustrating that the perceived color depends on lighting conditions.
Another physical aspect is that surfaces can only reflect colors present in the light source. A rose under white light can reflect red because red wavelengths are present in the light; under a green-only light, even a “red” rose would not look red – it might look dark because there are no red wavelengths to reflect (it would reflect what little it can of green, possibly appearing brownish or gray). Photographers and stage lighting designers exploit this: the same object can appear dramatically different in color under different colored lights. This underscores that color is a product of an interaction: light x object x observer. The object provides a spectral reflectance curve (a profile of how much it reflects at each wavelength), but that potential is realized only given light input and an observer to detect the output.
To quantify an object’s color-making potential, physicists and color scientists often measure its spectral reflectance – essentially how much light it reflects at each wavelength. A red rose petal might show high reflectance in the 600–700 nm range and low reflectance elsewhere. This physical data alone is not yet “color” in the human sense, but it tells us the rose has a disposition to look red to a standard observer under white light. Some philosophers (so-called color physicalists or realists) argue that such reflectance properties are the color (they define “red” as the property of having a reflectance curve that causes red experiences in humans). Others counter that while reflectance is an objective property, calling it “red” is only shorthand for its subjective effect – without an observer, it’s just a reflectance curve, not a color per se.
In any case, the physics perspective gives us a crucial piece: if the rose falls in the forest and no one sees it, the rose’s petals still interact with light in the same way. If sunlight is filtering through the canopy, the petals will still absorb and reflect as they always do, producing a surplus of red wavelengths in the scattered light. So physically, the event of the rose in the forest does produce certain wavelengths of light moving through space. However, whether that is “color” depends on the next step: detection by a visual system. The photons reflected from the rose would simply dissipate or be absorbed elsewhere if no eyes (or instruments) catch them. Without an eye to intercept those photons and a brain to interpret them, one can say the rose’s redness remains an unrealized potential. The physical groundwork (red wavelengths) is laid, but the perceptual payoff (seeing red) does not occur. We turn now to how the human visual system normally takes that input and creates the experience of color.
Human Color Perception: How the Eye and Brain Create Color
Color comes to life in the interaction between incoming light and the visual system of an observer. In humans, the first step of color perception happens in the retina of the eye. The retina contains photoreceptor cells that absorb light and convert it into neural signals. There are two main types of photoreceptors: rods, which are very light-sensitive but do not differentiate colors (they enable night vision in grayscale), and cones, which function in brighter light and are responsible for color vision. Humans typically have three types of cone cells, each with a different photopigment that makes it sensitive to a different range of wavelengths. These are often labeled as S, M, and L cones – for short, medium, and long wavelength-sensitive – roughly corresponding to blue, green, and red in terms of the portion of the spectrum they respond to. For example, S-cones are most responsive to light around 420–440 nm (violet-blue light), M-cones peak around 530–540 nm (green light), and L-cones peak around 560–580 nm (yellow-red light). When we look at a red rose, the long-wavelength (L) cones in our eyes will respond strongly to the red-rich light, the M-cones less so, and the S-cones minimally. The pattern of activation across the three cone types becomes the raw data for the color “red” in our nervous system.
However, it is crucial to note that individual cones themselves do not signal “colors” – each cone just increases its firing rate in response to photons, and any single cone’s response is ambiguous about color. An L-cone might fire a certain amount either because it received a moderate amount of purely red light or a larger amount of a mix of wavelengths that also stimulate it. It can’t tell the difference on its own. Only by comparing the responses of different types of cones can the visual system infer the actual color of the light. This was the basis of the classic trichromatic theory of color vision, first proposed by Thomas Young and later refined by Hermann von Helmholtz in the 19th century. The trichromatic theory states that three types of receptors (cones) are enough to account for human color vision, because any color we see corresponds to some combination of the three cone signals. Indeed, any spectral light can be “matched” by a mixture of three primary colors (as long as they are chosen appropriately, e.g. red, green, blue primaries) – a fact that is directly related to how our cones work, as we will see in the next section on metamers.
Once the cones convert light into electrical impulses, those signals undergo further processing in the retina and brain. Retinal ganglion cells – the next layer of neurons – integrate signals from multiple cones. Notably, at this stage the visual system introduces opponent processing (which we cover in detail in the following section). The outputs from the cones are mathematically combined into opponent channels (roughly a red vs. green channel and a blue vs. yellow channel, plus a brightness channel). The optic nerve carries these processed signals to the brain, particularly to the visual cortex. Specific areas of the brain (for instance, area V1 and V2 handle initial visual processing; area V4 has been implicated in color perception) further analyze these signals, contributing to our stable color perceptions. By the time the processing is complete, the brain presents us with an experience: e.g., the vivid red of the rose against the green background of the forest. This perceptual color is a mental representation triggered by the external stimuli.
One remarkable aspect of human color perception is how actively the brain constructs the color experience. The brain doesn’t merely read off wavelengths; it interprets input in context, applies corrections (like color constancy mechanisms that adjust for lighting changes), and even fills in color where none objectively exists (as in certain optical illusions). For example, in a phenomenon known as color constancy, our brain adjusts our perception of an object’s color to account for the color of the light source. A white sheet of paper looks white to us both under bluish sunlight and under reddish indoor lighting, even though the actual spectrum entering our eye is very different in each case. Our visual system compensates, so that we perceive the paper as consistently white. This is another indication that color is not just a readout of the raw wavelengths – it’s a result of complex neural processing aiming to represent the world consistently.
The key point is that without a functioning visual system to process light into the experience of color, those wavelengths remain unseen colors. If a rose’s reflected light enters a human eye, it triggers a cascade of neural events resulting in a perception of red. But if that same light never encounters an eye (or a device designed to detect color), then no such cascade occurs. The rose’s redness lives in that cascade, not in the rose alone. As one vision science text put it, color is the way our visual system encodes information about the distribution of light wavelengths reflected by objects. Without the visual system, the information might be there in the light, but it is never perceived or encoded as “color.”
Metamerism: Different Lights, Same Perceived Color
A powerful demonstration that color is dependent on perception (and specifically on our human visual system) is the phenomenon of metamerism. Metamers are physically distinct stimuli that appear identical in color to an observer. In other words, you can have two lights with completely different wavelength compositions, yet if they stimulate the three types of cones in the same ratios, they will look the same color to a normal human observer. This happens because our eyes reduce the rich spectral information of light into just three numerical signals (the outputs of S, M, L cones). Any two spectra that produce the same trio of cone responses will be indistinguishable in color for us.
One classic example: a monochromatic light at around 580 nm (which would appear yellow to us) can be perceptually matched by an appropriate mixture of red (around 650 nm) and green (around 530 nm) light. If you shine a pure single-wavelength yellow light in one spot and a combination of red+green in another spot, a person with normal vision can adjust the mixture until the two spots look identical in color. At that point, the 580 nm light and the red+green mixture are metamers – the person just sees two identical “yellow” spots, even though physically one is a single wavelength and the other is two wavelengths. The reason is that the single 580 nm light moderately stimulates the M-cones and strongly stimulates the L-cones, and by tweaking the red+green intensities, you can achieve the same M and L cone stimulation (with minimal S cone stimulation in both cases). The brain receives the same input signals from the cone layer for both stimuli and thus reports the same color. This effect underscores that color is defined by the observer’s response, not uniquely by the light’s physical makeup. An organism with a different visual system (say, a bird with four types of cones, or a hypothetical human with an extra cone type) could distinguish those two stimuli easily, because their sensory processing is different. But for us, once the information is compressed into our three cone channels, different spectra can become “confused” as the same color.
Figure: An illustration of metamerism. Left: A yellow ball illuminated by a monochromatic yellow light (single wavelength spike, Y). Right: The same ball’s color reproduced on a screen using a combination of blue (B), green (G), and red (R) light, as in an RGB display. The graphs below each scenario show the spectral distribution of light and the responses of the three human cone types (S=short, M=medium, L=long wavelength cones). Although the physical spectra differ – one is a single wavelength, the other has three distinct wavelength peaks – they elicit similar cone responses (bottom graphs). As a result, the human eye/brain perceives the same yellow color in both cases. Modern color reproduction technologies (television, monitors, printing) rely on such metameric matches, using combinations of primaries to trick our visual system into seeing a full range of colors.
Metamerism has a direct implication for the question of whether an unobserved rose is “still red.” The rose’s redness, to a human, is determined by how the rose’s reflectance spectrum interacts with our three cone sensitivities. If a rose reflects light mostly at, say, 650 nm and above, a human will see it as red because our L-cones will be strongly stimulated and M-cones moderately so, yielding that particular sensation. But one could imagine a different combination of wavelengths hitting the eye that produces the same cone responses – for instance, a mix of two wavelengths (one that stimulates L strongly and one that stimulates M appropriately) could, in principle, also look indistinguishably red. Without a human observer present, it does not even make sense to talk about which spectra would look the same or different, because “looking the same” is a perceptual outcome. The concept of metamers is defined relative to an observer’s visual system. It emphasizes that color equivalence is in the eye of the beholder. Physically, no two distinct spectra are truly the same; the equality only exists at the level of the perceptual processing. So if no perception occurs, the entire framework of “color matches” or “appearance” is moot.
In practical terms, that rose in the forest has a certain reflectance spectrum. Under sunlight, that means the light leaving the rose will have a spectral power distribution skewed towards longer wavelengths. If a human were there, that distribution would be interpreted as “red.” But in the absence of a human (or similar visual system), there is only the distribution of wavelengths – which could equally be described as a certain combination of radiation. Without an interpretative apparatus, calling it “red” is merely a projection of what would be seen by us, rather than a fact about the light itself. The light itself could be described by a spectrometer (an instrument that measures intensity at each wavelength) but that description would be a graph of intensity vs wavelength, not a color name. It takes a visual system like ours to reduce that complex spectrum to a single qualia of “red.”
Therefore, the phenomenon of metamers reinforces the idea that color is a creation of the sensory system. It shows that the same color experience can arise from different physical realities, meaning the color experience is tied to how the observer’s biology processes input. No observer, no processing; no processing, no color experience. Next, we examine another key insight from vision science that drives home how our brain can even generate color experiences in the absence of external stimuli: the opponent-process theory and afterimages.
Opponent-Process Theory and Visual Afterimages
Trichromatic theory describes the first stage of color vision – how cones encode light into three signals. The opponent-process theory, proposed by Ewald Hering in the late 19th century, describes a second stage of processing that better accounts for how we perceive color and particularly the relationships between colors. The opponent-process theory recognizes that certain colors are “opposites” in perception: for example, there is no such thing as a reddish-green or a bluish-yellow as a single color; red and green seem to mutually cancel, as do blue and yellow. Hering suggested that we have neural mechanisms that pit colors against each other in pairs: a red–green opponent channel and a blue–yellow opponent channel (along with a black–white or light–dark channel for brightness). In modern understanding, this happens through retinal ganglion cells and neurons in the lateral geniculate nucleus (LGN) of the thalamus that receive input from the cones and subtract one from another. For instance, one type of opponent cell might be excited by signals from L-cones (signifying red) and inhibited by signals from M-cones (signifying green), thus creating a red-versus-green output. Another cell might compare S-cone activation to the combined M+L (which corresponds roughly to yellow) to create a blue-versus-yellow signal. This opponent encoding means that the brain has channels where the two ends of the spectrum push against each other – when one is highly active, it suppresses the other. That’s why we don’t see “greenish red”: the neural channel that would carry “red” is either in one state or the other (excited vs. inhibited), not both simultaneously.
A vivid demonstration of opponent processing is the phenomenon of negative afterimages. If you stare at a strongly colored image for some time and then look at a neutral (white or gray) background, you will see an afterimage in the complementary colors. For example, stare at a red square for 30 seconds and then shift your gaze to a white wall – you will momentarily see a greenish spot the same shape as the square. The same happens in reverse (green yields a red afterimage), and blue yields yellow (and vice versa). What causes this? According to opponent-process theory, the neurons encoding, say, the red-green channel become fatigued or adapted from the prolonged stimulation by red. The red-stimulated neurons’ response weakens with time. When you then look at a white surface, you are now sending a balanced mix of all wavelengths to the eye (white light), which normally would excite red and green channels equally. But because the “red” side of the red-green mechanism is temporarily suppressed (tired out), the balance now tips in favor of the green side – so the white light is interpreted as “greenish” until the cells recover. In essence, the brain manufactures a green sensation internally as a rebound from the suppressed red channel. The same logic applies for blue/yellow opponent cells. The afterimage is a clear case where the color you perceive is not coming from the wavelengths currently hitting your eye (the wall was white, meaning equal wavelengths), but from the state of your visual neurons. It illustrates that color perception can be generated or strongly influenced by neural processing alone, not just by the immediate light stimulus.
Visual afterimages demonstrate the brain’s active role in color and support the idea that color is a mind-dependent phenomenon. If color existed only in the external world, independent of observers, then shining white light on a wall would always be perceived as white. The fact that your brain can momentarily see green on a white wall (because of prior adaptation) means the experienced color is coming from the observer’s own visual system dynamics, not solely from the light in that moment. The brain can create color qualia where physically none exist (the wall was objectively emitting equal energy of all visible wavelengths, yet you saw it tinted). This kind of effect underscores that what we perceive as color is a construction – one that normally correlates with external stimuli, but is ultimately produced by neural circuits.
The opponent-process theory and adaptation effects also remind us that perception of color is relative and context-dependent. Our experience of any given color is affected by preceding stimuli (afterimages), surrounding colors (simultaneous contrast effects, where a gray patch looks bluish on a red background and yellowish on a blue background, for example), and other factors like lighting, as mentioned before. All these contextual influences mean color isn’t simply “painted” on objects; it emerges from complex interactions in the visual system.
To bring this back to the question of the unseen rose: The rose’s petals reflecting certain wavelengths is one thing, but the actual experience of redness involves the whole chain – cone excitation, opponent-channel encoding, and cortical interpretation. If none of that chain occurs (because there is no observer), we can say that the rose’s potential to cause a red experience remains unfulfilled. And without the experience or some representation in a perceiver, calling it “red” is a category mistake according to the subjectivist view. The rose has a property (reflectance of certain wavelengths) that would lead to red if observed, but if it’s not observed, then in a literal sense no color is instantiated. Just as a sound requires an ear to be heard, color requires an eye (and brain) to be seen.
Philosophical Implications: Does Color Exist Without Perception?
The scientific insights from physics and neuroscience lend significant weight to a particular philosophical stance: that color is not an intrinsic property of objects, but rather a relational or subjective property that arises only through perception. This view is sometimes called color subjectivism or irrealism about color. The unseen rose problem is essentially asking: is an unperceived color a real color? The argument we have developed suggests the answer is “no” – without perception, what exists are just physical facts (wavelengths, surface reflectances), but not color as commonly understood.
Philosophers have long debated this. The subjectivist or eliminativist position (held historically by Galileo, Descartes, Locke, Hume, and many modern scientists) is that color (along with other secondary qualities like taste and sound) “exist only in consciousness”. John Locke, for instance, said that something like redness is in the rose only as a power to produce an idea in us when we look, but that in the rose itself there are just colorless particles reflecting light. Modern scholars echo this: Barry Maund sums up that in mainstream scientific understanding, “physical objects do not actually have the colors we ordinarily take them to have… those colors have no place in the physical account of the world”. From this angle, saying the unseen rose is not red is straightforward: red is the name of an experience or an appearance, and by definition no appearance occurs without an observer. There may be a fact of the matter about what wavelength mix the rose would reflect (and we could loosely call that its “color” in a physical sense), but the actual redness exists only “for” a perceiver. To be very precise, one might say: in the absence of observers, the rose has no color in the phenomenal sense – it has only a spectral reflectance property.
On the other side of the debate, color realists or objectivists argue that colors are real properties of objects (often identifying them with the surface’s spectral reflectance or some related physical property). Philosophers like Byrne and Hilbert (2007) defend the idea that objects are truly colored and that colors can be equated to physical types of reflectance. Under that view, the rose in the forest would still be red in the sense that it possesses the property (reflectance profile) that normally makes it look red. No one may see it, but it is still objectively red because if someone were to see it, they would see red, and that dispositional property is an objective fact. This is akin to saying a sugar cube is still sweet (has the property of producing sweet taste in tasters) even if no one tastes it – a dispositional property exists even when not manifest.
However, even many who take that dispositional view would agree that the experience of red does not exist without an observer. They just choose to use the term “red” to refer to the physical disposition as well. In everyday and scientific practice, this is common: we say “the rose is red” meaning it has certain physical qualities. The question at hand pushes us to clarify that meaning. If we define “red” strictly as the sensation or the appearance, then the unseen rose isn’t red because no appearance is happening. If we define “red” as “having a surface that reflects light of long wavelengths preferentially,” then the rose is red whether or not someone is there, but note that this definition is basically calling a certain reflectance curve “red” by convention. It’s not the original naive notion of red as a seen color.
The philosophical implications reach into discussions of reality and perception: Are colors part of the fabric of the external world or are they created by minds? The evidence from psychology and neuroscience strongly suggests that what we perceive (the qualitative color) is mind-dependent. This does not mean it’s an illusion in a pejorative sense – our color perceptions reliably correspond to real differences in objects (e.g., differences in reflectance). But it means color is a kind of interaction property. Philosopher Mazviita Chirimuuta, for example, argues that colors are not properties of objects alone or of subjects alone, but properties of the interaction between observer and object. In her view, if you remove either part of the equation (no object or no observer), the color does not exist in that scenario. A rose with no light or no observer is a rose with no color – the potential is there but no actual color.
One might wonder: what about non-human observers? If someone sees it, it’s red to them – but what if a creature with different color vision (say a color-blind person or an animal) sees it? A dog, which has only two types of cones (dichromatic vision), might not distinguish the red rose well from a green background; for them the rose might appear a kind of dark yellow or gray. Which is the “real” color? This variability underscores that color is tied to the observer’s perceptual system. The rose doesn’t have a single intrinsic color that all beings will agree on. Its “redness” is relative to the standard human visual system. So even if one insists the rose is red in a sense, it must be specified: red-for-humans under normal conditions. Without humans (or similar-eyed creatures) around, the concept of “red” has no anchor.
In philosophical terms, we can conclude that color is a secondary quality that requires a perceiving mind. Thus, if a rose falls in a forest and absolutely no one sees it (and let’s also say no recording devices or anything that “observes” it in any way), then from the standpoint of color experience, it is not red because no color experience has been formed. It still has the physical basis for redness – the rose’s petals have the same molecular structure and would reflect the same wavelengths – but “red” in the full sense exists only if someone sees it. As soon as an observer comes along (even hours later, if the rose is still intact and light conditions are appropriate), the rose can be seen as red. But until that interaction occurs, one can say the rose’s redness is an unactualized disposition, not an actuality.
This conclusion aligns with a modern scientific view summarized by Palmer (1999): “There may be light of different wavelengths independent of an observer, but there is no color independent of an observer, because color is a psychological phenomenon that arises only within an observer.” The unseen rose has the wavelengths, but not the color. Color happens when those wavelengths meet an eye and mind.
Conclusion
Interdisciplinary analysis leads us to a cohesive answer: if a rose falls in the forest and no one sees it, it is not truly red, because “red” is the result of a perceptual process that in this scenario never occurs. Physically, the rose continues to interact with light – absorbing some wavelengths and reflecting others. It possesses the properties that under the right conditions would make it appear red to humans. However, color in the meaningful sense exists only when those reflected photons stimulate an observer’s visual system and are interpreted by a brain. We have seen that distinguishing physical light from perceived color is crucial: the rose can produce red-spectrum light, but without perception, that remains just electromagnetic radiation, not the experience or quality of redness.
Insights from physics show that the rose’s color is contingent on lighting and reflection; insights from neuroscience and psychology show that color is constructed by the visual system (through cone responses, neural opponent channels, and brain interpretation). Phenomena like metamerism demonstrate that color is defined by the observer’s sensory apparatus, and opponent-process afterimages demonstrate that the brain can generate or alter color sensations independent of external stimuli. These lines of evidence converge on the view that color is a dependent reality – dependent on observers and their sensory-cognitive frameworks. Philosophically, this supports the notion that color is not part of the world in itself (at least not in the way we naively think), but a property that emerges through interaction with perceivers.
For an interdisciplinary audience, this conclusion resonates across fields. A philosopher sees in it a case of secondary qualities and the mind-dependent nature of certain aspects of reality. A physicist sees a confirmation that what’s “out there” are just particles and waves – color comes in only when a detector (like an eye) interprets those waves. A neuroscientist appreciates how the brain creates our color experience and might note that without neural activation, “red” is just a word. An artist or photographer intuitively knows that color depends on viewing conditions – the rose’s redness isn’t absolute, and they manipulate lighting and context to bring out or change colors. Cognitive psychologists note how context and expectation can even shift perceived colors, again showing the active role of the mind. All can agree, from their different angles, that an unperceived color is fundamentally different from a perceived one.
In everyday life, we will of course continue to say things like “roses are red” as a convenient truth. But as this analysis shows, such statements carry an unspoken clause: “roses are red to a typical human observer in normal light.” Remove the observer (or the light, or change the observer’s visual system), and the redness can vanish, in reality if not in potential. Thus, if a rose falls where no one sees it, its redness is like the sound of the falling tree with no listener – an event that never fully realized its sensory dimension. The redness was never seen, and without being seen, it is as good as not there. The unseen rose is only potentially red, not actually red. Color is a collaboration between the external world and our perception, and in the absence of that partnership, color simply does not bloom.
References
Barry, B. (2024). Color. In E. N. Zalta & U. Nodelman (Eds.), The Stanford Encyclopedia of Philosophy (Fall 2024 ed.). Stanford University.
Chirimuuta, M. (2015, July 21). The Reality of Color Is Perception. Nautilus.
Galilei, G. (1623/1957). The Assayer (Il Saggiatore). In S. Drake (Trans.), Discoveries and Opinions of Galileo (pp. 270–275). Garden City, NY: Doubleday.
Palmer, S. E. (1999). Vision Science: Photons to Phenomenology. Cambridge, MA: MIT Press.
Purves, D., Augustine, G. J., & Fitzpatrick, D. (2001). Cones and Color Vision. In Neuroscience (2nd ed.). Sunderland, MA: Sinauer Associates.
Silverstein, L. D., & Merrifield, R. M. (1985). The development of a color display for a dynamic flight simulator. Proceedings of the Human Factors Society 29th Annual Meeting, 1291–1295. (Referenced in on metameric color matching)
Young, T. (1802). On the theory of light and colours. Philosophical Transactions of the Royal Society of London, 92, 12–48. (Early theory of trichromatic color vision.)
Online Educational Sources:
Grose-Fifer, J. & Olman, C. (2025). Opponent Process Theory (Chapter 6.3). In Sensation and Perception (OpenStax/CUNY).
Physics Classroom (n.d.). Light Absorption, Reflection, and Transmission – Lesson 2. Retrieved from physicsclassroom.com.
Wikipedia. (2025). Metamerism (color). Wikipedia, The Free Encyclopedia. Retrieved March 28, 2025, from https://en.wikipedia.org/wiki/Metamerism_(color)
