Idealism and the Mind-Body Problem

February 15, 2026 | 3,497 words | 17min read

Paper Title: Idealism and the Mind-Body Problem

Link to Paper: https://philarchive.org/rec/CHAIAT-11

Date: 2017

Paper Type: Philosophy, Idealism, Panpyschism

Short Abstract: In this paper, David Chalmers provides a taxonomy of theories in idealism, introduces a new system to classify them, and investigates their usefulness in addressing the mind–body problem.

0. Introduction

There is a famous philosophical saying:

One starts as a materialist, then becomes a dualist, then a panpsychist, and ends up as an idealist.

The idea is roughly as follows:

1. Impressed by the success of science, one initially endorses materialism.
2. Confronted by the problem of consciousness, one notices a gap between physics and consciousness and endorses dualism.
3. Struggling to understand matter, one speculates that it might itself be conscious, leading to panpsychism.
4. Finally, seeing little reason to believe that anything besides consciousness exists, one comes to idealism.

This paper focuses on this final step: the move to idealism.

1. Varieties of Idealism

Broadly, the thesis of idealism is that the universe is, at its most fundamental level, mental. This stands in opposition to physicalism, which replaces mental with physical.

What counts as “mental”?

By mental facts, we mean mental properties, conscious experiences, as opposed to non-conscious mental states.

Often, idealism is understood more narrowly as a version of Berkeley’s thesis, which holds that appearances constitute reality. This form of idealism can be called anti-realism, as it claims that the physical world is only grounded in the experience of an observer. Formally:

For any non-mental fact (p) about concrete reality, what it is for (p) to obtain is for the corresponding appearances (or closely related appearances) to obtain.

Importantly, this statement is false for more realist versions of idealism. For realist idealism, the physical world exists independently; what is surprising is that its most fundamental nature is mental.

There are roughly two paths that lead to idealism, corresponding to anti-realist and realist forms:

1. Epistemological skepticism: we argue that we cannot know anything beyond appearances → anti-realist idealism.
2. The mind–body problem: questioning how consciousness arises → realist idealism.

There are many more varieties of idealism, which can be summarized as follows:

 1What constitutes reality?
 2├── Mental → Idealism
 3│    ├── Reality as it appears?
 4│    │    ├── Yes → Anti-Realism e.g., Husserl
 5│    │    │       - Modern view: phenomenalism
 6│    │    └── No → Realism e.g., Schopenhauer
 7│    │
 8│    ├── What minds constitute reality?
 9│    │    ├── Fundamental particles → Micro-Idealism
10│    │    │       - Classic: Leibniz
11│    │    │       - Modern: Philip Goff → panpsychism
12│    │    │       - Notes: Micro-Idealism → panpsychism, but not vice versa
13│    │    │         Example: non-idealist panpsychists assign both mental and non-mental properties to micro-entities (e.g., mass/charge are non-mental, but micro-experiences are mental)
14│    │    │
15│    │    ├── Humans/animals → Macro-Idealism
16│    │    │       - Classic: Hume, Mill
17│    │    │       - Notes: Macro-Idealism ⊄ phenomenalism
18│    │    │         Example: reality may consist of mental relations among macro-subjects that do not involve appearances
19│    │    │
20│    │    └── Cosmic mind → Cosmic-Idealism
21│    │            - Classic: Fichte, Schelling, Hegel, Buddhism
22│    │            - Modern: Bernard Kastrup → cosmopsychism
23│    │            - Notes: Cosmic-Idealism → cosmopsychism, but not vice versa
24│    │              Example: cosmopsychists may allow non-mental aspects of the cosmos
25│    │
26│    └── Is mentality tied to a subject?
27│         ├── Yes → Subject-Involving Idealism e.g., Berkeley, Fichte
28│         └── No → Non-Subject-Involving Idealism e.g., Spinoza, Plotinus
29│
30├── Matter → Physicalism e.g., Democritus
31└── Both → Dualism e.g., Descartes, medieval scholastics
32
33Cross-cutting / combination examples:
34- Berkeley can be interpreted as both cosmic and macro-phenomenalist: reality is grounded in God’s mind (cosmic) and our minds (macro).
35- Emergent panpsychists may be micro/macro idealists: both micro and macro minds are fundamental.
36- Micro-phenomenalists and cosmic-phenomenalists could exist: appearances are grounded in micro or cosmic minds.

2. Macro-Idealism

Macro-Idealism is the thesis that the mental states of humans are fundamental, and that all of reality is grounded in these states.

How does this grounding work?

Roughly speaking, the fact that the physical world appears a certain way grounds its being that way.

How can there be illusion or hallucination?

If the way reality appears grounds the way it really is, how can appearances be mistaken? A common answer is that there is something like a “normal appearance,” and illusions or hallucinations are deviations from it.

How can there be unperceived parts of the physical world?

For example, why does a light continue burning when one leaves the room? One typical answer is that the entities are ultimately grounded in the experiences of a cosmic or divine mind (e.g., Berkeley’s God).

Phenomenalism

Classical phenomenalism says that truths about the physical world are based on possible experiences.

• Weak metaphysical phenomenalism claims that physical facts depend on possible experiences but does not require full idealism.
• Strong metaphysical phenomenalism goes further, asserting that all facts depend on possible experiences, including potential or modal aspects of reality, forming a qualified form of idealism.

Problems with Phenomenalism

One major problem is the explanatory objection. Saying that appearance is reality demands some explanation of coherence, but phenomenalism provides none. For example, a table may appear a certain way to me from one angle, differently from another angle, and the next day it looks the same again. This coherence across appearances requires an explanation.

Non-phenomenalist views explain this coherence by positing a single, objective table. Phenomenalism, however, grounds the table solely in appearances or possible experiences, resulting in an array of fundamental truths rather than a single underlying object.

Possible Solutions

Several approaches attempt to address this problem:

• Berkeley proposes a divine mind to guarantee coherence.
• Structuralist approaches posit underlying structural facts about reality, independent of individual appearances.

These solutions are not entirely stable, as they must reconcile how physical reality appears consistent without relying on independent, non-mental entities.

Beyond Human Experience

In principle, idealism need not be tied to human experiences. Some views ground reality in the experiences of a cosmic mind (as in Berkeley, and in parts of Buddhism and Hinduism), while others appeal to the experiences of micro-minds, like Leibniz’s monads. These approaches are less dependent on “possible experiences,” since every part of reality could already be experienced by a cosmic or micro-mind. Nevertheless, it remains unclear what explains the order among these experiences.

Trying to maintain idealism only at the human (macro) level is much harder, because most of the physical world seems unrelated to what humans experience. Some ideas from quantum theory, like the notion that consciousness collapses the wave function—might sound macro-idealist, but they are usually interpreted as dualist rather than idealist.

A modern view, Giulio Tononi’s Integrated Information Theory, claims that only consciousness truly exists. However, if only macro-level systems are conscious, then vast portions of the universe remain unexplained, creating serious challenges for macro-idealism.

3. Micro-Idealism

Micro-idealism is the thesis that all concrete facts are grounded in the mental states of fundamental microscopic entities, such as quarks or photons.

The term micropsychism (used by Galen Strawson) refers specifically to the idea that fundamental micro-level entities possess mental states. On this terminology, panpsychism in the broader sense does not necessarily imply micro-idealism. Micro-idealism requires micropsychism, but not all versions of panpsychism include this commitment.

Even micropsychism does not entail micro-idealism:

1. Some panpsychists deny that macro-level minds are fully grounded in micro-level minds. Emergent panpsychists think macro-minds strongly emerge from micro-minds, while autonomous panpsychists think macro-minds do not wholly depend on them.
2. “Impure” panpsychists allow that fundamental micro-entities may also have non-mental properties, such as spatiotemporal features.

Motivation for Micro-Idealism

The motivation for micro-idealism is similar to that of panpsychism: the problem of consciousness, the inscrutability of matter, and the desire to see consciousness closely integrated with the physical world in a causal role.

This leads to the theory that micro-entities have experience, so-called micro-experiences, which contrast with human macro-experiences.

Panpsychism can be thought of as a middle path between materialism and dualism: it preserves the irreducibility of consciousness, gives it a causal role, and respects the causal closure of physics.

A particularly precise version of this view is called constitutive Russellian panpsychism. It holds that micro-experiences play the causal roles described by physics (e.g., realizing properties like mass), and that macro-level experiences, like ours, are constituted by these micro-experiences. This helps avoid the interaction problems faced by dualism.

Micro-idealism takes this further: it claims that all facts are grounded in the mental states of micro-subjects. Unlike standard panpsychism, it asserts that all fundamental properties are purely mental, making it a constitutive, reductionist, micropsychist, and “pure” form of panpsychism.

Micro-idealism has both strengths and weaknesses.

3.1 Strengths

• Monistic unity: Because everything fundamental is of the same kind, the view is unified and monistic, in contrast to impure panpsychism, which yields a form of property dualism.
• Comprehensive ontology: Micro-idealism offers a clear, systematic account of fundamental reality, unlike impure views that leave non-mental properties obscure.
• Avoids the interaction problem: Mental–mental interactions are conceptually simpler than mental–nonmental interactions, which challenge dualism.

3.2 Weaknesses

3.2.1 Explaining Space and Time

A key problem for micro-idealism is explaining all fundamental physical properties in mental terms. While micro-experiences might plausibly ground properties like mass or charge, it is much harder to see how they could ground spatiotemporal relations, which involve basic relations (like distance) between distinct entities.

To succeed, micro-idealism would need fundamental experiential relations between different subjects. However, the experiences we know are primarily properties of individual subjects, not relations among them. It is unclear what sort of experiential relation could fulfill the role that space and time require—a point noted by Bernard Kastrup in his discussion of analytical idealism.

Possible responses include:

1. Substantivalism: Treat space or spacetime as a single mental substance, with objects located relative to it. This introduces a kind of cosmic mind, but moves the view away from “pure” micro-idealism.
2. Intrinsic locations: Treat spatiotemporal location as an intrinsic property of each micro-entity, realized by micro-experiences. This would require a highly unorthodox physics.
3. Emergent spacetime: Deny that space and time are fundamental, claiming they emerge from deeper structure. Some modern physics theories (like string theory, loop quantum gravity, or causal set theory) explore such ideas. However, these approaches often replace ordinary spacetime with other fundamental relational structures, which may merely shift the problem.
4. Accept nonmental spacetime: Maintain space and time as non-mental while grounding all other facts in micro-experiences. This is a more qualified form of idealism, still closer to idealism than traditional physicalism.

3.2.2 Explaining Causal and Dispositional Properties

Micro-idealism must also account for causal and dispositional properties (like powers or tendencies). Russellian panpsychism grounds physical dispositions in mental properties, but philosophers debate whether dispositions are fully determined by their categorical bases. If they are not, it is unclear how all dispositional facts could be grounded purely in mental facts.

Possible responses mirror those for spacetime:

• Ground dispositions in mental features such as acts of will.
• Deny that fundamental dispositions exist (a Humean approach).
• Allow some basic causal truths that are not fully mental while still claiming a broadly idealist view.

Hedda Hassel Mørch proposes that phenomenal states themselves ground causal powers (e.g., pain grounding avoidance), which could yield an especially “pure” form of idealism.

3.2.3 Holism

Modern physics, particularly quantum mechanics, often treats fundamental properties (like the wave function) as attaching to whole systems or even the entire universe rather than to individual micro-entities. Philosophers like Jonathan Schaffer have suggested there may be no ultimate smallest level of reality. If true, micro-idealism may lack fundamental micro-entities to ground reality in, pushing the view toward cosmopsychism or cosmic idealism.

3.2.4 The Combination Problem

The combination problem, famously raised by William James, asks how countless micro-experiences combine to form unified macro-experiences like ours. Micro-idealism, as a form of constitutive panpsychism, faces this problem more sharply than other views, since it allows only mental ingredients in its explanation. This challenge concerns how subjects, qualities, and structures combine to yield coherent conscious experience.

4. Cosmic-Idealism

Cosmic idealism is the thesis that all concrete facts are grounded in the mental states of a single cosmic entity, such as the universe as a whole or perhaps a God.

Cosmic idealism entails cosmopsychism, the view that a cosmic entity has mental states, but the converse is not necessarily true (e.g., in non-constitutive or impure cosmopsychism).

The motivation for cosmic idealism is very similar to that of micro-idealism and panpsychism: it accommodates the irreducibility of consciousness while respecting the causal closure of physics.

This view can also be called constitutive Russellian cosmopsychism.

Starting with priority monism (Jonathan Schaffer), which holds that the universe as a whole is fundamental and has cosmophysical properties (like matter distributions or the wave function), Russellian cosmopsychism adds that the universe’s cosmo-experiential properties realize these cosmophysical properties by having the appropriate structure and causal roles.

Constitutive cosmopsychism goes further: these cosmic experiences also ground the macro-experiences of beings like us. In this view, the physical world is essentially the structured play of experiences in a cosmic mind. Cosmic idealism is a natural form of this, where all facts—including our own experiences—are grounded in the mental states of the cosmic subject. While cosmic idealism does not require Russellian cosmopsychism, the Russellian approach is the most straightforward way to connect cosmic mental states to physical reality.

Cosmic experiences could be very different from human ones. They might resemble human perception, thought, or imagination, reflecting the universe’s evolution, or they might be entirely unlike anything we know, with a unique phenomenology that mirrors the structure and dynamics of the cosmos.

4.1 Benefits of Cosmic Idealism

Cosmic idealism goes further than constitutive Russellian cosmopsychism in its purity, holding that all fundamental properties of the cosmic subject are mental. This gives the view several strengths:

• Unity: reality is grounded in a single subject.
• Comprehensibility: a single mental system can account for all phenomena.
• Causation: causal relations are simple, occurring within a single mind.

At the same time, cosmic idealism faces familiar philosophical challenges, particularly regarding spacetime, causation, and other general issues.

4.2 Challenges of Cosmic Idealism

Cosmic idealism alleviates many of the difficulties faced by micro-idealism.

4.2.1 Spacetime

Both micro- and cosmic-idealism face the challenge of finding experiential relations that can realize spatiotemporal relations. However, it is much easier to do this within the mind of a single subject than across multiple subjects.

For example, a single cosmic subject could have:

• Relations of co-consciousness and phenomenal feature binding
• Relative distributions within a sensory field
• Complex structures that mirror the evolution of spacetime

It is even conceivable that spacetime as a whole is realized by the cosmic subject’s spatiotemporal experiences. Questions remain: for instance, how relativistic phenomena could be realized experientially. But the principled obstacle is significantly smaller than in micro-idealism.

4.2.2 Causation

The options for explaining causation in cosmic idealism mirror those of micro-idealism, but some are more natural in the cosmic context.

If irreducible causal relations or dispositions exist, having them realized within a single cosmic mind (rather than across multiple subjects) seems particularly consistent with idealist principles.

The Mørch-style approach, that cosmic experiential states ground the relevant dispositions, is especially attractive here, since it is natural to see experiences within a single subject as giving rise to further experiences.

4.2.3 Holism

Holism poses no problem for cosmic idealism; in fact, it motivates moving from micro-idealism to cosmic idealism.

Even independently of idealism, if there are no fundamental micro-entities, one might adopt a holistic physical view in which the universe as a whole is the fundamental entity. Cosmic idealism combines this holistic perspective with the claim that these holistic physical properties are realized by mental properties.

4.2.4 The Combination (Constitution) Problem

Cosmic idealism faces an analog of the combination problem called the constitution problem: how do the experiences of the cosmic mind constitute the macro-experiences of beings like us? This parallels the combination problem in micropsychism, creating a unified challenge for both views.

The constitution problem has three aspects:

1. Subject constitution – how a cosmic subject can constitute individual macro-subjects.
2. Quality constitution – how cosmic experiential qualities form macro-qualities.
3. Structure constitution – how cosmic experiential structure forms macro-experiential structure.

While quality and structure issues resemble standard combination problems in panpsychism, the subject constitution problem is especially distinctive for cosmic idealism.

Subject constitution asks how a single cosmic subject could constitute individual macro-subjects, like human minds. Conceivability arguments (Philip Goff) suggest it is possible to imagine the cosmic mind existing without macro-subjects, implying that the cosmic mind might not metaphysically ground them.

Responses include:

• Nonconstitutive cosmopsychism – macro minds are not strictly grounded in the cosmic mind:
  • Emergent cosmopsychism – macro minds emerge strongly from the cosmic mind.
  • Autonomous cosmopsychism – macro minds do not fully depend on the cosmic mind.

These idealist variants resemble dualism: macro minds either affect the cosmic mind (threatening causal closure) or do not affect it (leading to epiphenomenalism). While mental–mental interaction is simpler than dualist mental–physical interaction, the original appeal of cosmic idealism as a unified explanatory framework is diminished.

Identity Cosmopsychism

To preserve pure cosmic idealism, one can adopt constitutive cosmopsychism, where macro-subjects are genuinely grounded in the cosmic subject. One strategy is identity cosmopsychism, which claims that all macro-subjects are identical to the cosmic subject. This avoids the conceivability problem (no distinct subjects exist) but faces objections:

1. Macro-subjects appear clearly distinct.
2. The cosmic subject presumably experiences far more than any single macro-subject.

A proposed solution is cognitive fragmentation: the cosmic subject has multiple modes or “masks,” each corresponding to a macro-subject. Each mode only accesses the experiences relevant to that macro-subject, while other experiences remain inaccessible. Kastrup (2017) compares this to dissociative identity disorder (DID). While revisionary, this model allows macro-subjects to be constitutive of the cosmic subject, preserving a pure form of cosmic idealism.

Non-Identity

Another approach is non-identity constitutive cosmopsychism, where macro-subjects are distinct from, but grounded in, the cosmic subject. Some proposals treat macro-subjects as parts, subsumptions, or “vortices” of the cosmic subject (Mathews 2011; Shani 2015; Goff forthcoming). Objections include that parts of a subject may not count as full subjects, and their existence is not obviously necessitated. Goff proposes adding unknown nonmental properties (“consciousness-plus”), but this compromises the purity of cosmic idealism.

Elimination

A third strategy eliminates subjects entirely, inspired by Buddhist or non-dual views: experiences exist without persisting subjects. Cosmic experience grounds conventional reality, and macroexperience is constituted by these ultimate, non-subject-involving experiences. This avoids the subject constitution problem but raises questions about how experiences combine to form the macro-experiences we perceive.

4.2.5 The Relational Problem

Cosmic idealism also faces the relationality problem, emphasized by G.E. Moore (1903). Experiences appear relational: when a subject sees something (e.g., blue), the experience seems directed at an object. Moore argued that this object is non-experiential, implying idealism is false.

Contemporary idealists respond by adopting representationalist views, where experiences relate to abstract properties (like blueness) or propositions (“this object is blue”) rather than mind-independent objects. Challenges remain: if the cosmic subject’s experiences appear to represent mind-independent properties, it may imply that the cosmic mind is “hallucinating.”

Responses include:

1. Accept hallucination – the cosmic mind’s relational experiences are not veridical.
2. Treat experience as non-perceptual – the cosmic mind imagines states of affairs.
3. Argue for veridicality – the cosmic mind accurately represents structural properties of reality, or only other experiences, not a mind-independent world.

A more radical solution denies relationality altogether, as in Advaita Vedanta or Yogacara, where fundamental experience lacks subject–object duality. Experiences may consist of pure awareness without objects or qualities, avoiding the relationality problem entirely.

4.2.6 The Austerity Problem

Cosmic idealism faces the austerity problem: the cosmic mind, in pure Russellian cosmopsychism, is extremely sparse, mirroring only the structure and dynamics of physics. It seems to lack thought, reasoning, valuing, or other mind-like features. Why a cosmic mind should be so austere is unclear.

Responses include:

1. Pure Russellian cosmopsychism – the cosmic mind mirrors physical structure exactly. Simple but austere.
2. Impure or enriched cosmopsychism – the cosmic mind has additional mental states (e.g., rationality or values). This introduces an excess-baggage problem, since mental states go beyond what physics requires.

One intriguing variant imagines the cosmic subject as a superintelligent being simulating universes (including ours). In this model, the austere mental states that constitute our universe are embedded within a richer cognitive life. This is akin to a simulation argument for cosmic idealism, suggesting our universe may exist in the mind of a superintelligent being rather than on separate physical hardware.

5. Conclusion

All standard solutions to the mind–body problem—materialism, dualism, neutral monism, and idealism—face serious challenges. However, idealism, particularly cosmic idealism, remains a plausible framework.

Cosmic idealism addresses many of the difficulties faced by macro-idealism and micro-idealism:

• It naturally accounts for the unity of experience.
• It simplifies the grounding of physical reality in mental states.
• It avoids many interaction and combination problems faced by micro-level approaches.

While not without challenges—including the constitution, relationality, and austerity problems—cosmic idealism offers a coherent, monistic alternative to traditional materialist or dualist approaches, making it a compelling contender in contemporary philosophy of mind.

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