Head to head
Functionalism vs Sam Harris
Functionalism and S. Harris’s Mystery of Consciousness, compared field by field from their entries in the Atlas.
At a glance
- Functionalism belongs to the Materialism family in Kuhn's Landscape of Consciousness, Sam Harris to Challenge.
- They give the same kind of answer on meaning and purpose.
- On AI consciousness, Functionalism says “Yes” and Sam Harris says “No”.
- On life after death, Functionalism says “Conditional” and Sam Harris says “No”.
- On mind uploading, Functionalism says “Likely” and Sam Harris says “No”.
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The claim
In brief
FunctionalismFunctionalism posits that mental states are defined by their causal relations to one another, to sensory inputs, and to behavioral outputs, independent of the physical medium (substrate) in which they are realized. The essence of consciousness is determined by how mental states function or operate, rather than by what they are materially composed of.
Sam HarrisThis perspective, offered as a challenge rather than a prescriptive theory, frames consciousness as an unbridgeable mystery that cannot be solved by purely physical means. Harris argues that physical descriptions are 'mute' regarding subjective experience; the only thing attesting to sentience is consciousness itself, creating a fundamental explanatory gap. He remains pessimistic that science can dispel this mystery.
What consciousness is
FunctionalismMental states are identified as functional states, constituted by their causal relations, roles, results, and outputs, implying they are realizable in any substrate that supports those functions.
Sam HarrisConsciousness is identified as subjectivity or sentience, which is fundamentally mysterious and unexplainable by purely physical processes.
Big questions
Can AI be conscious?Differ
FunctionalismYesFunctionalism holds that consciousness is based on function, not biology. If the correct functions can be realized computationally in non-biological substrates, AI consciousness is possible in principle and certain if Materialism is true.
Sam HarrisNoIf consciousness is irreducible subjectivity missing from physical descriptions, then advanced computation (AI, which is purely physical complexity) will fail to generate genuine sentience.
FunctionalismConditionalAs a physicalist theory, consciousness is tied to the substrate. Survival beyond death of the biological body is only possible if the functional mental state can be successfully transferred (uploaded) to a new, continuing substrate (virtual immortality).
Sam HarrisNoAs a naturalist, Harris implicitly aligns with the view that consciousness is tied to the physical organism, meaning its termination results in permanent non-existence, despite the mystery of its nature while alive.
FunctionalismLikelyFunctionalism serves as the theoretical basis for virtual immortality. If the functional role of the mental self can be perfectly duplicated and uploaded to a new medium, the first-person mental self is preserved.
Sam HarrisNoIf consciousness cannot be explained by purely physical processes, then duplication or uploading of the physical substrate will fail to capture or recreate the essential subjective self.
Does it give life meaning?Both agree
FunctionalismHumanistic onlyFunctionalism describes the mechanism by which mind/consciousness operates within a physical world, providing capacities for agency and reflection, but offers no rationale for ultimate cosmic meaning or teleology, aligning with the general stance of Materialism.
Sam HarrisHumanistic onlyThe mystery does not imply cosmic purpose, but Harris advocates finding personal truths through introspection, aligning with self-discovered (naturalized) spirituality and meaning.
Nature of mind
Ontology
FunctionalismPhysicalism (broadly, agnostic to substance). The theory is classified under Materialism, but it is metaphysically agnostic regarding nonphysical substances, focusing primarily on the functional description of mental states.
Sam HarrisSkeptical/Mysterianism (Justified: The view asserts the philosophical intractability and unbridgeable nature of the mind-body problem, aligning with core tenets of mysterianism, though without adopting a specific alternative ontology.)
Mind and body
FunctionalismMental states are functional states identical to the functional roles that are realized or instantiated in a physical substrate, leading to 'functional state identity theses'.
Sam HarrisUnbridgeable Gap / Non-reductive Correlation (Justified: Harris asserts that while physical processes correlate with consciousness, no analysis of these processes can logically yield a picture of consciousness, leaving an unbridgeable gap.)
Fundamental or emergent
FunctionalismEmergent. Consciousness arises from the functional organization realized by a sufficiently complex substrate (like neural tissue or computer chips).
Sam HarrisMystery (Justified: Harris declines to fully endorse emergence, stating that while consciousness may be the lawful product of unconscious processing, he does not find that sentence meaningful in explaining sentience.)
Qualia
FunctionalismThe theory traditionally struggles to account for phenomenal qualia, often addressing them by asserting that the qualitative feel is entirely exhausted by the functional role, or by coupling with representational theories.
Sam HarrisQualia (what it is 'like something' to be) are the phenomenon that physical events are 'mute' about, thus creating the unbridgeable mystery.
How it works
Mechanism
FunctionalismThe principle of multiple realizability, stating that mental state realization is independent of the physical substrate, contingent only upon the required function being instantiated.
Sam HarrisNone (Justified: The core premise is the failure of all current and foreseeable physical/mechanistic principles to explain subjectivity.)
Where it is
FunctionalismDistributed wherever the functional organization is successfully realized, regardless of whether the substrate is neural tissue or hardwired computing components.
Sam HarrisUnknown/Mysterious (Justified: While consciousness correlates with the brain, the theory explicitly rejects confining the explanation of consciousness to physical location or distribution because the physical world yields no evidence of consciousness.)
What it does
FunctionalismFunctions, roles, and outputs are dispositive. Mental states are causally effective because they are defined by their causal relations within the system (functional role).
Sam HarrisUnknown/Irreducible (Justified: Causal power is not explained by unconscious complexity. The presence of sentience is an ultimate mystery rather than a functional adaptation that can be described reductively.)
Evidence and criticism
Testability
FunctionalismConceptually and empirically testable. Thought experiments (like substrate replacement) probe its conceptual limits, and computational realization (AI) tests its empirical application.
Sam HarrisConceptually Untestable (Justified: If the gap is unbridgeable, as Harris claims, the mystery cannot be dispelled by empirical science as currently practiced.)
Tests so far
FunctionalismThe silicon chip replacement thought experiment is used conceptually to test whether phenomenal consciousness is preserved when the functional role is maintained across a change in substrate.
Sam HarrisNone (Justified: The framework is a diagnosis of science's failure to address the hard problem and does not propose empirical tests for the mystery itself.)
Criticisms
FunctionalismIt is criticized heavily for failing to account for phenomenal consciousness (qualia) by describing only the functional role, leading to the 'hard problem' challenge that functional roles may not exhaust the nature of conscious experience.
Sam HarrisIt functions primarily as a critique against reductionism and scientific optimism regarding consciousness, classifying the issue as an ultimate mystery, which reductionists reject as pessimism (mysterianism).
Sources
Key sources
Functionalism
- What is functionalism? (N. Block) (1980)
- What Is Functionalism? Consciousness, Function, and Representation (N. Block) (2007)
- Functionalism (J. Levin) (2023)
Sam Harris
- The mystery of consciousness (Part I & II), Sam Harris (2011)
- Explorations in Consciousness: Death Psychedelics and Mystical Experience (2023)