The Hard Problem
Philosopher David Chalmers distinguished the 'easy problems' of consciousness from the 'hard problem.' The easy problems (difficult but scientifically tractable) include: how does the brain integrate information? How do we focus attention? How does the brain control behavior? The hard problem: why does all this processing feel like anything at all? Why is there something it is like to be conscious, rather than just information processing in the dark?
Qualia
Qualia are the subjective, felt qualities of experience: the redness of red, the painfulness of pain, the taste of coffee. The philosopher's puzzle: could a person (or machine) behave exactly as if they experience red while having no inner qualitative experience? Such a 'philosophical zombie' would be physically and behaviorally identical to a conscious being but have no inner light. The zombie thought experiment shows that behavioral and physical explanation may not be sufficient to explain consciousness.
Physicalism and Its Problems
Physicalism holds that everything, including consciousness, is ultimately physical. The challenge: how to explain qualia in purely physical terms. Eliminative materialists (Churchland) deny qualia exist as described; they are folk-psychological fictions. Reductive physicalists (Dennett) argue that qualia can be explained in functional-physical terms — there is no explanatory gap, only conceptual confusion. Non-reductive physicalists accept that mental properties are real but supervene on physical properties without being reducible to them.
Dualism
Descartes' substance dualism — mind and body are distinct substances — is almost universally rejected by philosophers today (the interaction problem: how does an immaterial mind causally interact with a physical body?). Property dualism — there is only one substance but it has both physical and phenomenal properties — is more defensible but faces the same interaction challenges. Panpsychism (consciousness is a fundamental feature of reality) has gained academic traction as the alternatives founder.
Questions Fréquentes
What is the hard problem of consciousness?
The hard problem, named by David Chalmers, is explaining why physical processes in the brain give rise to subjective experience — why there is 'something it is like' to be conscious. The 'easy' problems (how the brain integrates information, controls behavior, focuses attention) are scientifically tractable. The hard problem asks why any of this feels like anything from the inside.
What are qualia?
Qualia are the subjective, felt qualities of conscious experience: the redness of red, the painfulness of pain, the specific taste of coffee. The philosophical question is whether qualia can be explained by functional or physical descriptions of the brain, or whether they represent something beyond physical description — a genuinely non-physical aspect of consciousness.
What is physicalism about the mind?
Physicalism holds that all mental phenomena, including consciousness, are ultimately physical. Physicalists disagree on how: eliminativists deny qualia exist as described; reductivists (Dennett) claim qualia can be explained functionally; non-reductivists accept that mental properties are real but irreducible. All physicalist positions face the challenge of explaining why physical processes produce subjective experience rather than just information processing in the dark.