Head to head
Functionalism vs Searle’s Biological Naturalism
Functionalism and Searle’s Biological Naturalism, compared field by field from their entries in the Atlas.
At a glance
- Both belong to the Materialism family in Kuhn's Landscape of Consciousness.
- Both treat consciousness as emergent.
- They give the same kind of answer on mind uploading and meaning and purpose.
- On AI consciousness, Functionalism says “Yes” and Searle’s Biological Naturalism says “Conditional”.
- On life after death, Functionalism says “Conditional” and Searle’s Biological Naturalism 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.
Searle’s Biological NaturalismBiological Naturalism posits that consciousness is a real, irreducible, subjective biological feature of the brain, entirely caused by lower-level neurobiological processes and realized as higher-level system features. This approach seeks to solve the mind-body problem by accepting the scientific worldview while acknowledging the first-person ontology of conscious experience.
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.
Searle’s Biological NaturalismConscious states are identified as real parts of the real world that are higher-level, system features of the brain, defined as states of awareness, sentience, or feeling that persist during wakefulness.
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.
Searle’s Biological NaturalismConditionalSearle rejects consciousness via simulation (Chinese Room Argument) but argues that if the causally sufficient biological mechanism is known, an artificial machine that implements that same mechanism could be conscious, as consciousness does not strictly require biological neurons, only sufficient causal power.
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).
Searle’s Biological NaturalismNoConsciousness is entirely physical and solely the product of biological brains; therefore, death of the brain and body means irrevocable, permanent non-existence.
Could a mind be uploaded?Both agree
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.
Searle’s Biological NaturalismYesIf consciousness is entirely explainable by physical/biological states, then duplicating those states (and their causal relations) in a non-biological medium would, in principle, allow for the uploading and continuation of the first-person mental 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.
Searle’s Biological NaturalismHumanistic onlyAs a materialist theory, Biological Naturalism struggles to rationalize ultimate cosmic meaning or purpose, though humanistic meaning created by ourselves remains possible.
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.
Searle’s Biological NaturalismPhysicalism (Biological Naturalism). It holds that consciousness is part of nature as a subjective, qualitative biological property, rejecting attempts to 'naturalize' it by denying its subjective 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'.
Searle’s Biological NaturalismConscious states are causally reduced to lower-level brain processes (causal reducibility), but are ontologically irreducible to these processes because consciousness has a subjective (first-person) ontology while its basis has an objective (third-person) ontology.
Fundamental or emergent
FunctionalismEmergent. Consciousness arises from the functional organization realized by a sufficiently complex substrate (like neural tissue or computer chips).
Searle’s Biological NaturalismEmergent
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.
Searle’s Biological NaturalismConscious states are inherently qualitative, in the sense that there is a distinct qualitative feel to being in any particular conscious state, and this qualitative feel is a real and irreducible part of the world.
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.
Searle’s Biological NaturalismThe principle is that all conscious states are reliably and universally caused by lower-level brain processes and realized as system features, functioning as a real biological machine.
Where it is
FunctionalismDistributed wherever the functional organization is successfully realized, regardless of whether the substrate is neural tissue or hardwired computing components.
Searle’s Biological NaturalismLocalized in the biological brain, specifically realized in the brain as higher-level or system features.
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).
Searle’s Biological NaturalismConscious states function causally (causal efficacy) as real parts of the real world, providing a basis for intentional action and interaction with the environment.
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.
Searle’s Biological NaturalismEmpirically testable in principle, as the theory requires finding the exact causal details of how lower-level brain processes cause consciousness.
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.
Searle’s Biological NaturalismThe theory is generally supported by empirical evidence from neuroscience showing the link between consciousness and brain activity (e.g., brain impairment, brain stimulation).
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.
Searle’s Biological NaturalismCritics dispute the claim that the causal connection between brain states and consciousness is fully established. Tension exists in maintaining materialism while arguing consciousness is ontologically subjective and irreducible to objective physical processes.
Sources
Key sources
Functionalism
- What is functionalism? (N. Block) (1980)
- What Is Functionalism? Consciousness, Function, and Representation (N. Block) (2007)
- Functionalism (J. Levin) (2023)
Searle’s Biological Naturalism
- The Rediscovery of Mind (1992)
- Biological naturalism (2007)
- What things are conscious? (2007)
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