What Is It Like to See Red? The Representational Theory of Sensory Qualities

Imagine you’re sitting in a dark room. Someone sets off a bright camera flash near your face. When you open your eyes, you see a green after-image floating in the air for a few seconds. It’s definitely green—not the wall behind it, not your own eyelid, just a floating patch of green that isn’t really there.

Now here’s a weird question: Where is that greenness?

It’s not outside your head—there’s no green blob floating in the room. And it’s not inside your head either—there’s nothing green inside your brain (if there were, you’d be in serious medical trouble). So where is it? This puzzle bothered philosophers for a long time. If you’re a materialist—someone who thinks everything is physical—you’ve got a problem. The greenness seems to be somewhere, but it can’t be physical.

This is the puzzle that gave birth to the representational theory of sensory qualities.

The Basic Idea

Here’s what representationalists say: When you see that after-image, you’re representing a green blob somewhere in the room. It’s like when you imagine a unicorn—there’s no actual unicorn, but you’re representing one. The greenness you experience is the greenness of that represented blob. It’s an intentional object—something your mind is about—not an actual physical thing.

So when philosophers say “there is a green thing Bertie is experiencing,” they mean the same kind of “there is” as in “there is a god the Greeks believed in.” The Greeks weren’t wrong that there was a god they believed in—they were wrong that such a god actually existed. Same with your after-image: you really are experiencing greenness, but the green thing isn’t actual. It’s just what your visual system is representing.

This lets materialists off the hook. The greenness Bertie experiences isn’t physical—but that’s okay, because it’s not actual. It’s just a content of his mental state, like the content of a belief or a dream.

What This Means for You

Think about the last time you saw something that wasn’t really there—a mirage on a hot road, a face in the clouds, a pattern in a dirty window. In each case, you had a visual experience with qualities (shimmering water, a face, a shape). According to representationalists, those qualities are just the properties of the things you’re representing, even though those things don’t exist.

This works for real perception too. When you look at a red apple on a table, the redness you see is the redness of the apple itself. Your visual system is representing that property. Same thing for hallucination: if you hallucinate a red apple, you’re still representing redness—just the apple isn’t real.

But Wait—Representation Is Cheap

Here’s where it gets tricky. I can represent redness by saying the word “red,” or writing it down, or thinking about it. But those aren’t visual experiences. So representing redness isn’t enough—you need to represent it in the right way.

What way is that? Well, through your visual system. Or your auditory system for sounds. Or your sense of touch for textures. Representationalists disagree about exactly what makes visual representation special, but they agree that not just any representation counts. It has to be the kind your senses produce—what philosophers call “sensory” or “nonconceptual” representation.

The Transparency Argument

Here’s a powerful reason to believe representationalism. Try this: Look at something colorful—a poster, a piece of fruit, whatever. Now try to focus your attention not on the thing you’re looking at, but on your experience itself. Try to notice features of your visual experience that aren’t features of what you’re seeing.

Philosophers like Gilbert Harman and Michael Tye say you can’t do it. Your attention just slides right through the experience to the objects in the world. The only features you can find are features of what you’re seeing. This is called the transparency of experience—like looking through a window and seeing only the view, never the glass itself.

If experience is transparent, that’s good evidence that the qualities you experience are really qualities of the objects you’re representing (or seem to be representing). The greenness of the after-image is just the greenness of the represented blob. There’s no mysterious extra property of “greenness” that belongs to the experience itself.

Objections: Where Representationalism Gets Sticky

Not everyone buys this. Here are some of the main challenges.

Non-Intentional States

What about pain? Or moods like anxiety or depression? It’s not obvious that these represent anything. A toothache doesn’t seem to be about something in the way that seeing a red apple is about an apple. Representationalists have answers: pain represents damage to a body part; anxiety represents that something bad is about to happen. But critics say these representations seem like an afterthought—the main thing about pain is how awful it feels, not what it represents.

Same Content, Different Feel

Sometimes, it seems like you can have two experiences with the same representational content but different feels. Peacocke’s tree example: You look at two trees at different distances. You represent them as the same height. Yet the nearer tree somehow “occupies more of your visual field.” That difference in “visual field occupancy” seems like a genuine difference in your experience, but not a difference in what you’re representing about the trees themselves.

Representationalists have responses: maybe you’re representing the visual angle, or the tree’s “apparent size,” or the fact that one tree is closer. But critics aren’t always satisfied.

Blurry Vision

Here’s a fun one. You’re looking at a sharp object without your glasses on. The object looks blurry. But you’re not representing the object as being blurry—you know it’s sharp. So what’s going on? There seems to be a difference between “seeing something as blurry” (like a blurry painting) and “seeing something blurrily” (like a sharp object without glasses). Representationalists have to explain this difference in terms of what’s represented—maybe the blurry vision represents less information, or represents fuzzy boundaries. It gets complicated.

The Inverted Spectrum

Imagine that everything you see as red, I see as green—but I’ve learned to call it “red” anyway. Our behavior is identical. According to some philosophers, this is possible. But if representationalism is true, then if we’re both looking at the same red object and representing it as red (since we both call it red), we should have the same experience. Yet intuitively, we might have different experiences.

This is a classic objection. Defenders of representationalism have various responses. Some say the inversion isn’t really possible. Others say it would make a difference to our representations somehow. Still others say our experiences would be different—there would be a representational difference we just can’t detect.

What About “What It’s Like”?

There’s a famous phrase in philosophy: “what it’s like.” Philosophers talk about “what it’s like to be a bat” or “what it’s like to see red.” This phrase can mean two different things:

The quality itself: The redness of the after-image. This is the sensory quality representationalists talk about.
What it’s like to experience that quality: The feeling of being aware of the redness. This seems different from the quality itself—it’s a property of the experience, not of what the experience represents.

Most philosophers think something very important is going on with this second sense. It’s what makes the “hard problem of consciousness” hard. Even if you explain all the representations in someone’s brain, you might not have explained what it’s like to be that person.

Representationalists disagree about whether this “what-it’s-like” property is also representational. Some say yes—it’s just representing your own mental state. Others say no—it’s something extra, maybe functional or biological. Some even deny that “what it’s like” properties exist at all, arguing that we’re just confused about what we introspect.

Why This Still Matters

The debate about representationalism isn’t just academic. It’s connected to big questions: Can consciousness be explained in physical terms? Is there something special about subjective experience that science can’t capture? Are we ever really aware of our own minds directly, or do we only ever see the world through them?

When you have a vivid dream and wake up confused, or get lost in a movie and forget you’re in a theater, or feel the weirdness of an after-image floating in front of you—you’re experiencing something that philosophers still struggle to explain. The representational theory offers one way of making sense of it. Whether it’s the right way is still very much an open question.

Appendices

Key Terms

Term	What It Does in the Debate
Sensory quality	The basic property of an experience, like the greenness of an after-image or the sweetness of a taste
Representation	The relation between a mental state and what it’s about—what makes your thought about something
Intentional content	What a mental state represents; the “aboutness” of a thought or perception
Transparency	The claim that when you try to examine your own experience, you only ever find features of what you’re experiencing, not features of the experience itself
What-it’s-like property	The feeling of having an experience—the “what it’s like to see red” as opposed to just redness itself
Materialism	The view that everything that exists is physical; consciousness must be explained without non-physical stuff

Key People

Gilbert Harman (1938–2012): American philosopher who revived the transparency argument, arguing that when you look at a tree you can’t find any features of your visual experience itself
Michael Tye (born 1950): British philosopher who defends strong representationalism and has written extensively about how to handle tricky cases like blurry vision
Ned Block (born 1942): American philosopher who argues against representationalism, defending the idea that there are non-representational features of experience (“mental paint”)
Frank Jackson (born 1943): Australian philosopher who created the famous “Mary the color scientist” thought experiment to argue that there are non-physical facts about experience
David Chalmers (born 1966): Australian philosopher who argues that “what it’s like” can’t be explained by physical facts and defends a form of representationalism that isn’t reductive

Things to Think About

If representationalism is true, what’s the difference between seeing a blurry object and seeing an object blurrily? Try to describe it without talking about what you’re representing.
You’re watching a movie. You know the characters aren’t real. But you still feel sad when something bad happens to them. Are those feelings representational too? What would the representationalist say?
Could there be two people who are molecularly identical but have different color experiences? If you think yes, what does that mean for representationalism? If you think no, what does that mean for the inverted spectrum argument?
What would it take to prove that the transparency thesis is wrong—that there really are features of experience you can find by introspecting? Try to describe one.

Where This Shows Up

Virtual reality and video games: When you feel like you’re really in a game world, you’re having experiences much like hallucinations. The representational theory helps explain why those experiences feel real even though you know they aren’t
Artificial intelligence: If we ever build a conscious AI, we’ll need to know whether its experiences are just representations or something more. Representationalism suggests consciousness might be easier to build than we think
Neuroscience and psychology: Researchers study how the brain represents the world. The question of whether those representations are experience, or just cause experience, is at the heart of the science of consciousness
Everyday disagreements about color: When you and a friend disagree about whether something is blue or green, representationalism suggests you might genuinely be having different experiences—representing different properties—even though you’re looking at the same object