Hard problem of consciousness
Explanation
David Chalmers in 1995 distinguished between the easy problems and the hard problem of consciousness. The easy ones —technically difficult but conceptually tractable— consist in explaining functions: how the brain integrates information, how it discriminates stimuli, how it produces verbal reports, how it controls behaviour. All are cognitive problems addressable by standard science.
The hard problem is different: why there is something it is like to be the brain. Why are physical processes accompanied by subjective experience? Why, when the brain processes wavelengths of light, is there the qualitative quality of red; why, when it processes noxious stimuli, is there something called pain. No purely functional account seems to answer this question.
The classical metaphor is the explanatory gap. We can imagine all the brain's physical processes operating without inner experience, like philosophical zombies. This suggests that subjective experience is not the same as physical processes nor logically derived from them, even though it is correlated with them.
The hard problem has several lines of response. Deflationists (Dennett, Frankish) deny that there is any such problem: the intuition of the hard problem is a cognitive illusion; once all the easy problems are explained, we will have explained everything that needs explaining. Inflationists (Chalmers himself, Goff, Kastrup) accept the problem and propose to expand our ontology: panpsychism, idealism, property dualism.
In between are positions backing specific theories that claim to dissolve the problem: IIT (Tononi) holds that consciousness IS integrated information with a specific structure; GWT (Dehaene, Baars) that it is information broadcast globally; higher-order theories that it is representation of representations. Each one claims to have closed the explanatory gap.
The hard problem marks the difference between a complete science of cognition and a genuine theory of consciousness. Even if neurosciences advance enormously in the coming years, the question of whether that is enough to explain subjectivity remains one of the liveliest and most open philosophical and scientific debates of our time.
Strengths
- Articulates with precision the central difficulty of the field.
- Catalyst for a renewed research programme on consciousness.
- Allows theories to be classified by their explanatory ambition.
- Restores first-person experience as a legitimate problem.
Main critiques
- For functionalists/eliminativists, the 'hard problem' is illusory: qualia are not what we think.
- Excessively pessimistic: confuses practical difficulty with theoretical impossibility.
- The easy/hard distinction is not sharp in scientific practice.
- Critique from integrated information theory: the problem is addressed by specifying structure, not by adding entities.