Idealisms—Overview

Idealism is the theory that consciousness is ultimate reality, the fullness of the deepest level of all existence, the singular fundamental existent. It is the theory of consciousness that takes consciousness to its maximum meaning: Consciousness is rock-bottom reality.

The focus here is ontological idealism, where ultimate reality is mind or awareness or thought, while everything else, including all physical worlds and universes and all that they contain, is derivative or illusionary. (I do not consider epistemological idealism, where all we can know is constrained by the structure of human thought.) (Guyer and Horstmann, 2023).

Consciousness as ultimate reality is the age-old claim, rooted in some wisdom traditions, that the only reality that's “really real” is consciousness—everything else, from physical laws to physical brains, is the generative product of an all-pervading and all-encompassing “cosmic consciousness.” Each individual instance of consciousness—human, animal, artificial, or otherwise—is a subset of this cosmic consciousness, the ultimate superset.

Idealism has a rich intellectual history, especially in the 18th century (e.g., Berkeley, Kant) and 19th century (e.g., Hegel, Bradley); it was anticipated by elements of 17th-century philosophy and continued to develop into the 20th century (Guyer and Horstmann, 2023). Though often eliciting “the incredulous stare” (in David Lewis's delightful phrase), Idealism is taken seriously by philosophers. Moreover, it is the foundation of major religious traditions, especially among those that arose in ancient India.

To the surprise of some, Idealism as a theory of consciousness has not been fading in light of scientific advances. If anything, Idealism's explanatory star seems on the ascent, shining brighter, as consciousness maintains its mysteries and Idealism attracts more adherents.

Contemporary Perspectives on Idealism

David Chalmers muses, “One starts as a materialist, then one becomes a dualist, then a panpsychist, and one ends up as an idealist. I don't know where this comes from, but I think the idea was something like this.

• First, one is impressed by the successes of science, endorsing materialism about everything and so about the mind.
• Second, one is moved by problem of consciousness to see a gap between physics and consciousness, thereby endorsing dualism, where both matter and consciousness are fundamental.
• Third, one is moved by the inscrutability of matter to realize that science reveals at most the structure of matter and not its underlying nature, and to speculate that this nature may involve consciousness, thereby endorsing panpsychism.
• Fourth, one comes to think that there is little reason to believe in anything beyond consciousness and that the physical world is wholly constituted by consciousness, thereby endorsing idealism” (Chalmers, 2020d).

Chalmers defines idealism broadly “as the thesis that the universe is fundamentally mental, or perhaps that all concrete facts are grounded in mental facts. As such it is meant as a global metaphysical thesis analogous to physicalism, the thesis that the universe is fundamentally physical, or perhaps that all concrete facts are grounded in physical facts. The only difference is that ‘physical’ is replaced by ‘mental.’”

Idealists are not necessarily committed to anti-realist views about the physical world, though some are, especially among Eastern traditions. It is perfectly coherent for an idealist to regard the physical world as “real” in the sense that it exists when no one is looking; “it just has a surprising nature,” having been formed from mental fundamentals (Chalmers, 2020d).

Chalmers distinguishes three types of idealism:

1. “Micro-idealism is the thesis that concrete reality is wholly grounded in micro-level mentality: that is, in mentality associated with fundamental microscopic entities (such as quarks and photons).”
2. “Macro-idealism is the thesis that concrete reality is wholly grounded in macro-level mentality: that is, in mentality associated with macroscopic (middle-sized) entities such as humans and perhaps non-human animals.”
3. “Cosmic idealism is the thesis that concrete reality is wholly grounded in cosmic mentality: that is, in mentality associated with the cosmos as a whole or with a single cosmic entity (such as the universe or a deity)” (Chalmers, 2020d).

Thus, micro-idealism has all fundamental forces and particles as entirely (not in part) mental; macro-idealism privileges what we commonly call mental as somehow constituting the foundations of reality; and cosmic idealism can be conceived as kinds of pantheism or theism, though not the dominant strands, of course. Moreover, there is resonance between these three kinds of idealism and three similar kinds of panpsychism, the rough difference being that whereas in panpsychism the mental, while everywhere, is not everything, in idealism, the mental is both everything and everywhere.

Idealism’s Spiritual and Philosophical Resonance

To Huston Smith, world religion expert and devotee, matter is not fundamental, but consciousness is. “Matter is like an iceberg protruding out of the sea of consciousness.” Consciousness can never be destroyed, he said, but “can oscillate between different forms,” which leads, he recognizes, to the issue of death. “We know what our consciousness is like; we can't explain it, but we can experience it. What will it be when we drop our body? Well, what we can say is if consciousness is the fundamental reality and it can't be destroyed, consciousness will continue. The light on the television screen will never go out. Now what the image on that screen will be after death, after we drop the body, we do not know. That's the ultimate mystery” (Smith, 2007).

To philosopher-theological scholar David Bentley Hart, “reason abhors a dualism, all phenomena should ideally be reducible to a single, simpler, more capacious model of reality. So, then, rather than banishing mind from our picture of nature, perhaps we should reconsider the ancient intuition that nature and mind are not alien to one another precisely because nature already possesses a rational structure analogous to thought” (Hart, 2022b).

Not sufficiently contrarian, Hart then considers “the ground of the possibility [that] regular physical causation is a deeper logical coherence of rational relations underlying all reality.” Perhaps, more to his point, “mind inhabits physical nature not as an anomaly, but as a revelation of the deepest essence of everything that exists.”

To Steven Richheimer, scientist and meditator, consciousness is the foundational property of reality. He seeks to demonstrate that of the two fundamentally opposing ontologies or theories of reality, materialism, which is “bottom up” with upward causality, and spirituality, which is “ground substance” with “top down” causality, “the evidence from the various branches of science as well as religious, psychological, and human experience clearly point to spirituality as the more credible theory of reality” (Richheimer, 2025).

Although Idealism sounds simple to describe—all is consciousness and only consciousness—I [RLK] am fascinated by the diversity of its expressions.