Head to head
Epiphenomenalism vs Integrated Information Theory
Epiphenomenalism Theory and Integrated Information Theory (IIT), compared field by field from their entries in the Atlas.
At a glance
- Epiphenomenalism belongs to the Dualism family in Kuhn's Landscape of Consciousness, Integrated Information Theory to Information.
- On AI consciousness, Epiphenomenalism says “Likely” and Integrated Information Theory says “No”.
- On life after death, Epiphenomenalism says “No” and Integrated Information Theory says “Uncertain”.
- On mind uploading, Epiphenomenalism says “Likely” and Integrated Information Theory says “No”.
- On meaning and purpose, Epiphenomenalism says “Humanistic only” and Integrated Information Theory says “Uncertain”.
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The claim
In brief
EpiphenomenalismThis theory posits that consciousness is a non-reducible product of the biological brain, but mental states have absolutely no causal power over physical reality. Our subjective awareness is real, yet our perception that our thoughts cause actions is mistaken, as consciousness is entirely inert, like foam on an ocean wave.
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
EpiphenomenalismConsciousness is identified as phenomenal properties that are ontologically distinct from physical properties but are causally dependent on them (Physical → Phenomenal).
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
EpiphenomenalismLikelyIf consciousness is merely a non-causal byproduct (foam) of physical processes in the brain , replicating those physical processes in AI should produce the same conscious states without the non-causal mental states hindering functional replication.
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.
EpiphenomenalismNoConsciousness is entirely physical and solely the product of biological brains. This physical dependence precludes survival beyond bodily death.
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.
EpiphenomenalismLikelyThe inert nature of consciousness means that uploading the physical states would necessarily duplicate the epiphenomenal mental states. The inert 'foam' should have little impact on achieving virtual immortality.
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.
EpiphenomenalismHumanistic onlyAs a philosophical materialism theory, it provides no ultimate meaning or purpose. Since consciousness is causally inert, it cannot confer cosmic teleological value.
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
EpiphenomenalismWeak form of Dualism or Non-Reductive Physicalism. It affirms the complete causal closure of the physical.
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
EpiphenomenalismMental states are entirely the product of biological brains. Physical states cause phenomenal states, but phenomenal states have no causal effect on the physical (one-directional causation).
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
EpiphenomenalismEmergent. Consciousness is solely the product of biological brains.
Integrated Information TheoryConsciousness is defined by intrinsic existence and characterized as belonging to the basic description of reality. The theory rejects emergence.
Qualia
EpiphenomenalismPhenomenal properties (qualia) are real and ontologically distinct from physical properties , but they are epiphenomena and thus causally inert.
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
EpiphenomenalismThe principle of the 'causal closure of the physical' dictates that mental states, whatever their nature, must be entirely inert byproducts.
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
EpiphenomenalismEntirely located in the physical, biological brain.
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
EpiphenomenalismMental states have no causal powers. The mind is entirely inert and there is no 'top-down causation'; consciousness is a non-functional byproduct.
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
EpiphenomenalismConceptually challenged. Its primary claim—that conscious states lack causal force—is counterintuitive and difficult to test empirically, as it involves proving a negative causal link.
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
EpiphenomenalismNot stated
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
EpiphenomenalismThe theory is counterintuitive because it strongly seems to us that our phenomenally conscious states causally matter. It forces the acceptance that our sense of mental causation (thoughts causing things) is a 'kind of illusion or trick'.
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
Epiphenomenalism
- Consciousness (2019)
- Facing up to the Problem of Consciousness (1995)
- What Is Consciousness? (Little Debates about Big Questions), A. Kind and D. Stoljar (2023)
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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