Qualia: The Mystery of Human Experience Science Cannot Explain

Qualia (pronounced kwahl-ya) is perhaps the most fascinating concept in psychology and the philosophy of mind. It refers to every subjective experience of consciousness — something no microscope can ever access. It’s not only about emotional experiences like joy or sorrow, but also about the raw feeling of sensory reality such as seeing, hearing, taste, smell, pain, touch, and more.

On a physical level, music is simply a collection of sounds: information about frequencies at different pitches that can be measured, recorded, reproduced, or programmed. Yet, attached to those vibrations is the inner experience of pleasure in listening, which science cannot define.

A person doesn’t merely hear sounds, they experience them.
A person doesn’t merely know that they are hungry or full, but they feel hunger and fullness. A person doesn’t merely know that the body is in pain, but they feel the experience of pain.

Sound waves, nerve signals, chemical messages are just information arriving in the brain. Qualia does not describe the information itself, but the subjective sensation that accompanies it. That sensation is what we refer to as qualia.

The Redness of Red

Consider the example of color. We all know what “red” is, and we can agree that “this apple is red.” But alongside that knowledge is the experience of seeing red.

To illustrate the wonder of this inner experience, philosopher Frank Jackson proposed a thought experiment known as Mary’s Room. Mary is a scientist who spends her entire life in a black-and-white room, studying everything there is to know about color vision. She has complete scientific knowledge of color, wavelengths, and how the brain processes them. The moment Mary steps outside and actually sees color for the first time, she gains something entirely new: not factual knowledge of color, but the experience of seeing color.

Science can explain observed phenomena and how the brain processes them, but it cannot address the “observer within” who has the experience. No amount of physical data about the world or the brain can add to our understanding of qualia. Hence, qualia is not a physical concept.

Why Qualia Cannot Be Shared

We can never truly explain to someone blind from birth what it’s like to see color, nor to someone deaf from birth what it’s like to hear music. Even if they master all scientific facts about sight and sound, the lived experience will always remain unknown to them.

Moreover, every qualia is unique. Two people may both see the same red apple, yet their internal experiences will differ, shaped by their personality, memories, and background. These differences in qualia create the uniqueness of each person’s inner world. No two human beings have the same internal experience. Hence the old saying: “There’s no arguing about taste or smell.” We all perceive the same data, but experience it differently, which is why one person prefers green while another prefers yellow.

The Limits of Science

The concept of qualia is so compelling precisely because science cannot define it, although every human being intuitively understands what it is.

Again, let’s consider the example of color. Science can measure light waves and show that a long wavelength corresponds to red. It can program numbers into pixels on a digital screen to display red. It can explain how the wave hits the retina, is translated into electrical signals, and is recognized by the brain. A computer can be programmed to detect “red” automatically.

But the computer doesn’t know the qualia of seeing red.

Science can describe every detail of how vision or hearing works, but it cannot touch the actual feeling of seeing or hearing. Mapping billions of neurons tells us nothing about the inner experience of consciousness.

As Nobel Prize–winning physicist Erwin Schrödinger (famous for “Schrödinger’s Cat”) once said: “The sensation of color cannot be accounted for by the objective picture of light waves. Could the physiologist account for it if he had fuller knowledge than he has of the processes in the retina and the nervous processes set up by them in the optical nerve and in the brain? I do not think so.”

If a robot were to ask us what thirst feels like, we could explain it scientifically as a bodily need for fluids. But no description of the mechanics explains why thirst is so uncomfortable — only humans know the lived experience of thirst.

Qualia, Torah, and the Value of Life

Thirst, hunger, pain, or the color red are not just signals processed by the brain, but are lived inner realities. This is the essence of qualia.

Our sages taught that every human being is a world unto themselves. The Mishnah (Sanhedrin 4:5) says: “Therefore, man was created alone, to teach that anyone who destroys a single soul, it is as though he destroyed an entire world; and anyone who saves a single soul, it is as though he saved an entire world.”

Each person is a “complete world” because each person’s experience of the world is unique. No two people live it the same way, nor have the same role in life.

Our sages also taught: “The King of kings, the Holy One, Blessed be He, stamps every person with the seal of Adam, and not one of them is like his fellow. Therefore, every person must say: For my sake the world was created.”

This individuality carries moral weight. Jewish law rules that one life may never be sacrificed for another — not even the life of a Torah scholar for that of an “ordinary” person. As the Talmud asks: “Who says your blood is redder? Perhaps your fellow’s blood is redder?” (Pesachim 25b).

This principle contrasts sharply with tyrants like Hitler and Stalin, who saw human beings as no more valuable than bacteria. Hitler himself wrote: “Man is nothing but a ridiculous cosmic bacterium.” (Ian Kershaw, Hitler: Nemesis, p. 436).

The Torah, by contrast, taught 3,300 years ago: “Whoever sheds the blood of man, by man shall his blood be shed; for in the image of God He made man.” (Bereishit 9:6)

Compassion Through Qualia

Qualia is also the root of compassion. Our sages said: “Do not judge your fellow until you have reached his place.” (Pirkei Avot 2:4). This can be understood on a deeper level: because we can never enter another’s inner world of experience — their qualia, we cannot know what trials they face or how they experience them. Only God, who “sees into the heart” (Shmuel I, 16:7), can truly judge.

(Photo: shutterstock)

(Photo: shutterstock)