Head to head
Higher-Order Thought Theory vs Russellian Monism
Rosenthal’s Higher-Order Thought and Russellian Monism, compared field by field from their entries in the Atlas.
At a glance
- Higher-Order Thought Theory belongs to the Materialism family in Kuhn's Landscape of Consciousness, Russellian Monism to Neutral Monism.
- Higher-Order Thought Theory treats consciousness as emergent; Russellian Monism treats it as fundamental.
- On AI consciousness, Higher-Order Thought Theory says “Possible” and Russellian Monism says “Likely”.
- On life after death, Higher-Order Thought Theory says “No” and Russellian Monism says “Conditional”.
- On mind uploading, Higher-Order Thought Theory says “Possible” and Russellian Monism says “Likely”.
- On meaning and purpose, Higher-Order Thought Theory says “Humanistic only” and Russellian Monism says “Uncertain”.
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The claim
In brief
Higher-Order Thought TheoryDavid Rosenthal holds that a mental state is conscious when its subject has a higher-order thought that he or she is in that state, a thought that need not itself be conscious and does not seem to rest on inference. Mental qualities such as the redness of a sensation exist whether or not they are conscious; Rosenthal explains them separately, by how they map the perceptible properties we can discriminate.
Russellian MonismRussellian Monism posits that the physical world, described by physics only in terms of structure and relations, has an intrinsic nature (quiddities) that is phenomenal or proto-phenomenal. This approach integrates consciousness into the fundamental reality while avoiding the traditional problems of dualism and reductive materialism.
What consciousness is
Higher-Order Thought TheoryA state’s being conscious consists in the subject being aware of it by way of a suitable higher-order thought that one is in that state.
Russellian MonismConsciousness (or proto-consciousness) is the intrinsic, categorical nature or property ('quiddities' or 'inscrutables') underlying the relational structure of physical reality described by physics.
Big questions
Can AI be conscious?Differ
Higher-Order Thought TheoryPossibleSince consciousness depends on having suitable higher-order thoughts about one’s own states, a system able to form such thoughts would meet the condition in principle.
Russellian MonismLikelyIf consciousness is intrinsic to matter/energy, and the combination problem can be technologically harnessed, then artificial systems built from physical substrates should achieve consciousness.
Higher-Order Thought TheoryNoConscious states are natural states of an organism, so nothing remains conscious once those states stop occurring.
Russellian MonismConditionalSurvival is unlikely for the individual conscious aggregate unless the combination mechanism is preserved or the theory aligns with a cosmic monist view, as individual consciousness (the macroscopic combination) would likely dissolve upon biological death.
Higher-Order Thought TheoryPossibleIf the relevant first-order states and higher-order thoughts were reproduced, the view gives no principled reason the copy would lack consciousness.
Russellian MonismLikelyA single-stuff reality should permit virtual immortality, provided advanced technology can manipulate and harness the micropsychic properties to accurately reproduce the macroscopic conscious aggregate digitally.
Higher-Order Thought TheoryHumanistic onlyThe theory is a naturalistic account of mental states and carries no cosmic purpose.
Russellian MonismUncertainMonisms generally allow for ultimate meaning/purpose/value. If RM takes a priority monist form with evolving consciousness, cosmic purpose may be implied.
Nature of mind
Ontology
Higher-Order Thought TheoryPhysicalism (naturalistic functionalism)
Russellian MonismNeutral Monism or Physical Monism or Phenomenal Monism (variant dependent); fundamentally Monistic.
Mind and body
Higher-Order Thought TheoryMental states, their qualities, and the higher-order thoughts that make them conscious are all natural states of the organism; Rosenthal expects neural correlates of consciousness to be whatever mechanism produces the higher-order awareness.
Russellian MonismMind and physical world are deeply intertwined, with mental properties constituting the intrinsic nature of fundamental physical entities (the categorical bases of physical dispositions).
Fundamental or emergent
Higher-Order Thought TheoryEmergent
Russellian MonismPrimitive (at the fundamental level of reality, as phenomenal or proto-phenomenal properties of micro-entities).
Qualia
Higher-Order Thought TheoryMental qualities are fixed by their role in perceptual discrimination and occupy a ‘quality space’ that mirrors the similarities among perceptible properties. Because these qualities do not depend on consciousness, a sensation can have qualitative character without being conscious, as in subliminal perception.
Russellian MonismQualia correspond to the phenomenal properties (or their precursors) that constitute the intrinsic nature of fundamental matter.
How it works
Mechanism
Higher-Order Thought TheoryA non-inferential higher-order thought that one is in a given state, which makes that first-order state conscious even when the thought itself is unconscious.
Russellian MonismThe key principle is the existence of unobserved, intrinsic categorical properties ('quiddities') of matter that are phenomenal, thereby grounding consciousness in fundamental reality without expanding the physical ontology of relations.
Where it is
Higher-Order Thought TheoryNot stated
Russellian MonismLocated in the intrinsic properties of fundamental micro-level physical entities or potentially instantiated by the universe as a whole (priority monism).
What it does
Higher-Order Thought TheoryNot stated
Russellian MonismAvoids the causal exclusion problem of dualism by embedding consciousness into the fundamental properties of the physical world, meaning consciousness underlies physical reality itself.
Evidence and criticism
Testability
Higher-Order Thought TheoryConceptually testable
Russellian MonismSpeculative/Conceptual. Its fundamental claims regarding intrinsic properties are generally beyond empirical access or mathematical modeling.
Tests so far
Higher-Order Thought TheoryNot stated
Russellian MonismNot stated
Criticisms
Higher-Order Thought TheoryFirst-order theorists argue that higher-order awareness is an unneeded extra ingredient, and deflationists say being aware of a conscious state is like ‘smiling a smile’. Rosenthal replies that a deflated awareness cannot explain the contrast between conscious and unconscious states.
Russellian MonismThe primary challenge is the combination problem, which is critical: explaining how microphysical properties combine to form complex, integrated macro-level consciousness. If Panprotopsychism is assumed, it faces the problem of deriving consciousness (qualia) from proto-phenomenal properties.
Sources
Key sources
Higher-Order Thought Theory
- Rosenthal’s Higher-Order Thought, Landscape of Consciousness, David Rosenthal (2005)
Russellian Monism
- What is Russellian Monism?, T. Alter and Y. Nagasawa (2012)
- Russellian Monism, T. Alter and D. Pereboom (2019)
- Panpsychism and Panprotopsychism, D. Chalmers (2016)