Is Mind-Brain Type Identity Theory a Convincing Theory of Mind?
I will conclude that while MBTIT is a significant step toward a scientific philosophy of mind, it ultimately fails due to the multiple realisability of mental states and the persuasive arguments for eliminativism regarding our unscientific folk-psychological concepts
- Mind-Brain Type Identity Theory (MBTIT) claims that mental states are ontologically reducible to brain states. A 'type' of mental state (e.g., pain) is identical to a 'type' of brain state (e.g., c-fibre stimulation) - Unlike dualism, MBTIT is an identity theory: mental states are not just caused by the brain, they *are* the brain. It is an 'ontological' rather than 'analytic' reduction, meaning the identity is a matter of fact, not linguistic synonymy - I will evaluate MBTIT's reliance on Ockham's Razor, the challenge of Multiple Realisability, and the eliminativist critique that our mental concepts are too unscientific for reduction. I will conclude that MBTIT is not convincing
Section 1: Smart's Identity Theory and Ockham's Razor
- Smart's use of Ockham's Razor is an abductive argument (inference to the best explanation). It is only valid if physicalism and dualism are equally supported by the evidence - Dualists argue that their theories (like the Knowledge or Zombie arguments) provide stronger deductive or inductive evidence for non-physical properties. If those arguments succeed, preferred simplicity (Ockham's Razor) becomes an invalid reason to ignore the complexity of consciousness - However, if dualist arguments are deemed to fail, MBTIT remains the most parsimonious explanation for the perfect correlation between mind and brain found in modern scans
J.J.C. Smart: Ockham's Razor and the Science of Correlation
- Smart argues that science reveals a perfect correlation between mental types and physical types (e.g., pain and c-fibre stimulation). While correlation doesn't strictly prove identity, identity is the simplest explanation - Following Ockham's Razor ('entities should not be multiplied beyond necessity'), we should not posit 'nomological danglers' (laws that exist outside the physical system) if we can explain the mind through the brain alone - Therefore, mental states are brain states as a matter of scientific fact, much like lightning is electrical discharge
Section 2: The Multiple Realisability Issue
- The 'biological function' defense (that octopuses feel a different 'type' of pain) is a weak ad hoc move. It saves the theory by making it trivial. If 'pain' is split into a thousand species-specific types, we lose the general concept of pain altogether - Putnam's 'Alien' version is decisive because it uses logical possibility to bypass empirical skepticism. If we can even *conceive* of a conscious entity with different hardware, then the mental 'type' cannot be identical to the human 'physical' type. Identity requires 1:1 necessity, which multiple realisability breaks
Hilary Putnam: The Multiple Realisability Objection
- Putnam argues that the same mental state (e.g., pain) can be realized in completely different physical systems. Evolution wouldn't produce 'pain' in only one specific way across the universe: - An octopus has no c-fibres, yet clearly experiences pain when injured - A silicon-based alien might have a completely different 'brain' but still possess mental states - If pain is identical to c-fibre stimulation, then an octopus cannot be in pain. Since an octopus *is* in pain, MBTIT's identity claim is false. Mental states are 'multiply realisable' and cannot be reduced to a single physical type
Section 3: MBTIT vs. Eliminative Materialism
- The 'predictive power' of folk-psychology is a strong practical defense, but it doesn't prove the concepts are scientific. Alchemy had predictive power for centuries before being eliminated by Chemistry - Identity theory relies on the hope that 'beliefs' and 'desires' map perfectly onto brain circuits. But if neuroscience reveals a 'messy' reality where these concepts don't exist as clear units, elimination is the only logical path. This makes Identity Theory appear like an' optimistic but misguided attempt to save unscientific terminology
Paul & Patricia Churchland: The Eliminativist Critique
- Eliminativists argue that identity theory is misguided because it tries to reduce 'folk-psychology' (common-sense concepts like belief and desire) to neuroscience. However, folk-psychology is a failing theory that cannot explain sleep, learning, or mental illness - You cannot reduce a bad theory to a good one; you must eliminate it. Lightning wasn't 'reduced' to Zeus's anger; the concept of Zeus's anger was eliminated and replaced by electricity - If mental concepts are unscientific, identity theory's attempt to find their brain-equivalents is a 'category mistake' doomed to fail
- MBTIT marks the transition from speculative dualism to a materialist worldview, using J.J. Smart's 'simplest explanation' (Ockham's Razor) to bridge the gap between correlation and identity - However, the theory is fatally undermined by Multiple Realisability. The logical possibility of silicon-based aliens or copper-headed octopuses experiencing pain proves that 'pain' cannot be identical to any specific human neuro-chemical process - Furthermore, the eliminativist challenge shows that our folk-psychological concepts (like 'belief' or 'desire') are likely too imprecise to be reduced to hard neuroscience. If reduction is impossible, we should expect elimination rather than identity. Thus, MBTIT fails