Philosophical Naturalism Cannot Account for Qualia

Critics of naturalism argue that even a complete scientific description of the brain processes involved (e.g., neural structures and functions) leaves out the intrinsic, inner feeling of the experience itself. This is sometimes referred to as the "explanatory gap" or the "hard problem of consciousness". The argument is that no amount of physical description can answer why a specific physical process is accompanied by an inner feeling at all.

Definitions 

Qualia:  the raw, subjective qualities of experience—the "what it's like" aspect of having a sensation. Examples include the ouchiness of pain, the redness of a sunset, or the taste of a lemon.

Philosophical naturalism: The view that only natural laws and forces exist; the universe is a closed system, excluding deities or spirit. Also known as Metaphysical Naturalism

Naturalism: The Objective View

Naturalism is defined by its reliance on objective, third-person descriptions.

It posits that everything in the universe can be fully explained by natural processes and laws, as understood through empirical science. Science describes the world from the "outside." For example, a scientist can describe a brain state by measuring neuron firing rates, chemical levels, and electrical signals. These are facts that any observer can verify.

Qualia: The Subjective View

Qualia represents the subjective, first-person nature of experience, which stands in direct contrast to objective data.

Qualia refers to the "qualitative aspects" of consciousness—specifically, "what it's like" to be in a certain state. This includes the "ouchiness" of pain, the specific taste of a lemon, or the sensation of seeing the color red. These are facts that only the subject (the person experiencing them) can access.

The Conflict

The conflict is that these two descriptions do not seem to overlap.

Critics argue that even if you have a "complete scientific description" of the brain's physical processes (the objective view), you have still left out the "intrinsic, inner feeling" of the experience (the subjective view). The problem is naturalism claims to explain everything via physical laws, but if it cannot explain why a physical process feels like something from the inside, then its explanation of the universe is incomplete.

The Explanatory Gap

The "Explanatory Gap" is the term used to describe the fundamental disconnect between physical biological processes and subjective conscious experience.

Science can theoretically provide a complete scientific description of the brain, mapping every neural structure and function involved in a reaction. However, this description completely leaves out the intrinsic, inner feeling of the experience itself.

Even if you fully understand the mechanics of how the brain processes light waves (the "easy" problem), there is nothing in that physical description that explains why that process should feel like seeing red rather than seeing blue or why it should feel like anything at all. This is why the explanatory gap is often referred to as the hard problem of consciousness.

The Unanswered "Why"

Ultimately, the explanatory gap highlights a limitation in naturalistic explanations. The core argument is that no amount of describing how neurons fire can answer the question of why that specific physical process is accompanied by an inner conscious feeling.

Note: The quale of "seeing red" is the unique, subjective, intrinsic feeling or raw feel of redness, which is the internal, private experience itself, distinct from the physical properties like light wavelengths or brain activity that cause it; it's what makes seeing red feel like red and not blue, a warm, alerting, visceral sensation.

The implications of Philosophical Naturalism inability to Account for Qualia

Naturalism claims the natural world (governed by physical laws) is all that exists. If qualia (subjective feelings) are real but cannot be broken down into physical processes (like neurons firing), they represent a reality outside physical laws. Thus a complete scientific/naturalistic explanation of the universe would actually be incomplete because it fails to describe the subjective reality of existence.

If facts exist (like "what it feels like to see red") that are not physical facts, then the core tenet of Naturalism, that only physical things exist, is incorrect. This suggests consciousness might be a fundamental constituent of the universe (like mass or energy) rather than a biological accident. This pushes toward alternatives like Panpsychism (mind is everywhere) or Dualism, both of which contradict Philosophical Naturalism.

For more on Panpsychism see here. 

Functionalism and Emergentism. 

These are two Naturalist responses that attempt to account for qualia without resorting to Dualism (souls) or Eliminativism (saying feelings don't exist).

Functionalism: "It's What It Does, Not What It Is"

Functionalism is currently the dominant theory in the philosophy of mind. It argues that a mental state (like "pain") is defined solely by its functional role, its cause-and-effect relationship with inputs, outputs, and other mental states.

Functionalists argue that "pain" isn't a specific biological material (like C-fibers firing). Instead, "pain" is just whatever state is caused by tissue damage and causes you to scream or pull away.

This theory allows for the possibility that aliens or AI could have qualia. If a silicon robot has an internal state that functions exactly like your pain state, then the robot is in pain.

Functionalists view the mind as software running on the brain's hardware. They argue that qualia are simply the way this software processes information about the world.

The biggest problem for functionalism is the "Philosophical Zombie" argument. Critics argue you could build a robot that functions perfectly (screams when hit) but has zero inner experience. If that's possible, then functionalism is missing the most important part: the feeling itself.

Emergentism: "More Than the Sum of Its Parts"

Emergentism takes a different approach. It accepts that qualia might be undeniably different from standard physical matter, but argues they are a natural byproduct of complexity.

Just as "wetness" is a property of water that doesn't exist in a single hydrogen atom, consciousness is a property that "emerges" when billions of neurons interact in a specific complex network.

Weak Emergence: Qualia are surprising, but if we knew enough about the brain, we could deduce them from the physics (just like we can explain a hurricane if we know enough about air molecules).

Strong Emergence: Qualia are a fundamentally new kind of natural phenomenon that appears at a high level of complexity. They cannot be reduced to just physics, but they are still natural laws, not supernatural ones.  Emergentists argue that we shouldn't expect to find "feelings" in atoms. Qualia are a higher-level reality that nature produces when matter gets organized enough.

Summary Comparison of Functionalism and Emergentism

Theory	View on Qualia	The Metaphor
Functionalism	Qualia are functions. If it acts like pain, it is pain.	Software: The code determines the outcome, regardless of the computer brand.
Emergentism	Qualia are complex properties. They arise from the system's structure.	Wetness: Water molecules aren't wet, but the ocean is.

Refuting Functionalism

Functionalism argues that mental states are defined by what they do (their cause-and-effect role), not what they feel like. The primary refutation is that it is possible to replicate the function without replicating the feeling.

• The "Philosophical Zombie" (Absent Qualia): This is the most famous objection. It is theoretically possible to build a system (like a silicon robot) that functions exactly like a human, like screaming when hit, avoiding damage, and processing data, but has zero inner experience. If such a "zombie" is possible, then having the right "functional state" is not enough to guarantee consciousness.

• Inverted Qualia: Functionalism cannot account for the specific nature of an experience. Two people could function identically (both call a strawberry red and stop at traffic lights), but one might internally experience "green" while the other experiences "red." Since their functional roles are identical, but their experiences are different, functionalism fails to explain the experience itself.

• The "China Brain": Philosophers like Ned Block argue that if you organized the entire population of China to pass signals to each other via walkie-talkies in the exact same pattern as neurons in a brain, the nation would be functionally identical to a mind. However, it is absurd to claim the nation itself would suddenly feel pain or taste chocolate. Therefore, function alone does not create a soul or mind.

Refuting Emergentism

Emergentism argues that consciousness is a property that naturally appears ("emerges") once matter reaches a certain level of complexity, much like "wetness" emerges from water molecules. The refutation argues this is a label, not an explanation.

• The "Brute Fact" Objection (It's Just "Magic"): Critics argue that saying consciousness "emerges" is scientifically empty. Unlike "wetness" (which can be deduced from the geometry and forces of H2O molecules), there is no logical way to deduce "subjective feeling" from "neuron complexity." Saying it "emerges" is just a fancy way of saying "a miracle happens here" without explaining how or why.

• The Explanatory Gap Remains: Weak emergence (like a traffic jam emerging from cars) is easy to explain because the whole is just the sum of the parts. But consciousness requires Strong Emergence—where a completely new type of reality (subjective experience) pops out of objective matter. This violates the scientific principle of continuity; you cannot get "subjectivity" out of "objectivity" just by adding more parts.

• The Causal Exclusion Problem: If physical laws (neurons firing) fully explain why your hand moves, then the "emergent" conscious mind has nothing left to do. It becomes a "ghost" that watches but cannot act. If emergentists claim the mind does act back on the brain ("downward causation"), they violate the fundamental laws of physics.