Head to head
Crick and Koch’s NCC vs Integrated Information Theory
Crick and Koch’s Neural Correlates of Consciousness (NCC) and Integrated Information Theory (IIT), compared field by field from their entries in the Atlas.
At a glance
- Crick and Koch’s NCC belongs to the Materialism family in Kuhn's Landscape of Consciousness, Integrated Information Theory to Information.
- On AI consciousness, Crick and Koch’s NCC says “Yes” and Integrated Information Theory says “No”.
- On life after death, Crick and Koch’s NCC says “No” and Integrated Information Theory says “Uncertain”.
- On mind uploading, Crick and Koch’s NCC says “Yes” and Integrated Information Theory says “No”.
- On meaning and purpose, Crick and Koch’s NCC says “Humanistic only” and Integrated Information Theory says “Uncertain”.
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The claim
In brief
Crick and Koch’s NCCThis theory proposes a scientific agenda to identify the Neural Correlate of Consciousness (NCC), defined as the minimum activities in the brain that are jointly sufficient and necessary for any specific conscious perception or subjective experience. It asserts that consciousness is entirely physical and can be fully reduced to these specific brain activities.
Integrated Information TheoryIIT is an original, radical model that proposes a definition for conscious experience and specifies which physical systems can possess it, starting from the phenomenology of consciousness (axioms). It translates these axioms into physical postulates based on intrinsic cause-effect power, featuring a mathematical measure Φ(Phi) to quantify a system's capacity for informational integration, which correlates with the degree of consciousness.
What consciousness is
Crick and Koch’s NCCConsciousness (phenomenal consciousness/qualia) is identified as the Neural Correlate of Consciousness (NCC), the precise minimum pattern of neural activity in the brain necessary and sufficient for subjective experience.
Integrated Information TheoryConsciousness is identified as a Φ-structure, a maximally reduced conceptual structure existing in 'qualia space'. An experience is identical to this conceptual structure, meaning its phenomenal properties correspond precisely to the physical properties of the cause-effect structure unfolded from the physical substrate of consciousness (PSC).
Big questions
Can AI be conscious?Differ
Crick and Koch’s NCCYesIf consciousness is entirely reducible to physical organizational patterns (NCC), then non-biological systems capable of replicating those precise patterns should also become conscious, barring technological constraints.
Integrated Information TheoryNoKoch, a proponent, argues that consciousness is not computable. Digital computers have negligible integrated information (Φ(Phi)) due to hardware structure, meaning they can never be sentient, regardless of intelligence.
Crick and Koch’s NCCNoAs a Materialist theory, consciousness is wholly dependent on the physical brain; cessation of brain function entails the end of consciousness.
Integrated Information TheoryUncertainIf phenomenal consciousness requires a radically new structure (like IIT's postulates), the potential permanence of these 'inscrutable things' cannot be rejected, leaving the possibility of survival open, even though IIT does not explicitly espouse life after death.
Crick and Koch’s NCCYesIf the NCC states can be perfectly measured and replicated in a digital or artificial medium (mind uploading), the resulting system would be functionally and phenomenally identical, achieving virtual immortality in principle.
Integrated Information TheoryNoIf consciousness is a fundamental property tied to real cause-effect power, a digital simulation (uploading) would only create a 'perfect zombie'—an entity that acts like the original but lacks subjective consciousness—because the simulation is virtual, lacking the required real cause-effect power.
Crick and Koch’s NCCHumanistic onlyConsistent with Materialism, consciousness is a biological product of evolution and physics, conferring no ultimate cosmic meaning or teleology beyond that which humans create for themselves.
Integrated Information TheoryUncertainWhile the measurement and analysis of consciousness do not convey ultimate meaning, the speculative nature and novelty of the innumerable nth dimensional conceptual structures (conscious percepts) warrants suspending judgment on ultimate meaning/purpose/value.
Nature of mind
Ontology
Crick and Koch’s NCCReductive Physicalism/Materialism. The NCC approach is considered macroscopic materialism.
Integrated Information TheoryIIT's fundamental ontology is the ontological primacy of phenomenal existence, based on an intrinsic powers view where what truly exists in physical terms are intrinsic entities capable of cause and effect. Koch notes that the theory insists consciousness must be incorporated into the basic description of reality at the rock-bottom level.
Mind and body
Crick and Koch’s NCCIdentity Theory. Mental states are wholly identical to and fully explained by the physical NCC states.
Integrated Information TheoryIIT asserts an explanatory identity: an experience is identical to a Φ-structure. It contends that the conscious entity is the Φ-structure expressing its causal powers, not the neural substrate itself. This framework leaves no room for emergence or dualism.
Fundamental or emergent
Crick and Koch’s NCCEmergent
Integrated Information TheoryConsciousness is defined by intrinsic existence and characterized as belonging to the basic description of reality. The theory rejects emergence.
Qualia
Crick and Koch’s NCCQualia (the qualitative feel of experience) are identified with the minimum neural activities (NCC) that are jointly sufficient for specific conscious perception, although the mechanism for this identity remains the central 'hard problem' challenge.
Integrated Information TheoryDistinct conscious experiences are conceptual structures in a 'qualia space'. The qualitative feel (phenomenal properties) corresponds one-to-one to the physical properties of the maximally irreducible cause-effect structure, which is also called a quale.
How it works
Mechanism
Crick and Koch’s NCCThe search for and definition of the Neural Correlate of Consciousness (NCC): the specific minimum neural activities necessary and sufficient for subjective experience.
Integrated Information TheoryThe core principle is Integrated Information (Φ(Phi)), which quantifies the system's irreducibility. The Exclusion Postulate ensures that only the maximally irreducible cause-effect structure (the Φ-structure) exists intrinsically, defining the boundaries and grain of consciousness.
Where it is
Crick and Koch’s NCCLocalized in specific brain areas. Early candidates included the claustrum (as a 'conductor' coordinating percepts); later candidates focused on the posterior cerebral cortex (temporo-parietal-occipital hot zone).
Integrated Information TheoryConsciousness is not limited to biological brains. IIT predicts the conscious structure resides in the posterior cortex (occipital, parietal, and temporal cortices). Systems with maximally irreducible intrinsic cause-effect power possess consciousness.
What it does
Crick and Koch’s NCCConsciousness is directly caused by, and is identical to, the NCC activity. NCC mechanisms (spikes, flows, circuits) are seen as constitutive of phenomenal consciousness.
Integrated Information TheoryConsciousness is identified as unfolded intrinsic causal power, which is the ability to effect change. Only this intrinsic entity (the Φ-structure) can cause, supporting the claim that true free will exists for systems with high Φ(Phi).
Evidence and criticism
Testability
Crick and Koch’s NCCEmpirically testable. The search for the NCC is defined as a scientific program seeking testable biological bases for consciousness.
Integrated Information TheoryIIT claims scientific testability, employing quantitative measurement. However, critics argue that the theory is not truly empirically tested, and its core predictions may be idiosyncratic.
Tests so far
Crick and Koch’s NCCIdentifying specific clusters of neurons or brain regions (like the claustrum or posterior cortex) that are active during conscious experience.,Measuring electrophysiological activity (e.g., action potentials and neural circuits).
Integrated Information TheoryCalculating Φ(Phi) for specific neural networks (e.g., visual cortex).,Monitoring brain activity as subjects slip into anesthesia.,Adversarial collaboration experiments testing predictions about sustained activity in the posterior cortex.
Criticisms
Crick and Koch’s NCCThe primary tension is the 'explanatory gap': identifying a correlation (NCC) does not explain the identity statement of how physical activity (spikes/chemicals) literally generates phenomenal feel (qualia). The failure to identify a 'clear' NCC after decades of research is a practical limitation.
Integrated Information TheoryThe theory faces criticism for anti-common sense predictions (imputing consciousness to simple objects). A public letter characterized IIT as 'pseudoscience'. Critics challenge that experiments test only idiosyncratic predictions and not the core metaphysical ideas. Chalmers noted the 'pseudoscience' label was disproportionate and caused vast collateral damage.
Sources
Key sources
Crick and Koch’s NCC
- Towards a neurobiological theory of consciousness, F. Crick and C. Koch (1990)
- What is the function of the claustrum?, F. Crick and C. Koch (2005)
- The Quest for Consciousness: a Neurobiological Approach, C. Koch (2004)
Integrated Information Theory
- From the phenomenology to the mechanisms of consciousness: integrated information theory 3.0, Oizumi, Albantakis, Tononi (2014)
- Consciousness: here, there and everywhere?, Tononi and Koch (2015)
- Only what exists can cause: an intrinsic powers view of free will, Tononi et al. (2022)
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