Idealism
Idealism is a form of monism which says that the single substance is Mind and that the material world is a construct of the mind rather than it having a separate existence. It is at the opposite pole from physicalism which says that material is the single substance and mind os a construct of that.
Idealism comes in several versions.
Absolute Idealism
Hegel [Hegel 1807] describes “Absolute Idealism” in his book “The Phenomenology of Spirit” [Hegel 1807]. According to Hegel, the “Absolute Spirit” is the ultimate reality that underlies all of existence, and individual minds are ultimately expressions of this universal consciousness.
There are similarities between Hegel’s philosophy of absolute idealism and some Hindu and Buddhist views, particularly those of Advaita Vedanta and Mahayana Buddhism. However there are also important differences.
For example, Hegel emphasises the role of self-consciousness and the rational structure of reality, while Advaita Vedanta emphasises the role of intuition and direct realisation of ultimate reality, and Mahayana Buddhism emphasises the role of compassion and the liberation of all sentient beings from suffering.
Additionally, Hegel’s philosophy is rooted in the Western philosophical tradition, while these Eastern views emerged from their respective cultural and religious contexts.
Subjective Idealism
Berkeley [Berkeley 1948] describes “Subjective Idealism”. According to Berkeley, individual minds are distinct but ultimately depend on the perception of other minds and on a shared system of language and meaning.
Analytic Idealism
Kastrup [Kastrup 2014] [Kastrup 2024] calls his view Analytic Idealism, and it’s probably the closest modern Western analogue to certain non-dual traditions—but with analytic rigour.
There is one Consciousness and this is the only fundamental reality. What we call the “physical world” is the extrinsic appearance of mental processes. Individual minds (you, me) are “dissociated alters” of that universal mind. A bit like DID on a Cosmic scale.
According to this view, the brain does not produce consciousness; it filters / constrains it. Physical laws are the outworking of the structure of Consciousness.
Interface model
In his book “The case against reality”, Donald Hoffman [Hoffman 2020] presents a model which is close to idealism but with differences. Hoffman’s core claim is that Evolution shaped perception for fitness, not truth so the things we experience, such as chairs, colours, space etc. is analogous to icons on a computer desktop. They correspond to things in the real world but they are not literally those things.
Then, starting from the uncontroversial “Perception is not a literal picture of reality It’s a simplified, fitness-driven model” he makes a leap to saying “The physical world (space-time, objects) is not fundamental – Consciousness is fundamental” which is close to a form of Idealism.
Solipsism
In one extreme form of Idealism, solipsism, it is considered that there is only one Mind, one’s own, and that everything and everyone else is a construct of it.
This view has the advantage that our experience would not be contradicted, things would seem to be exactly as they do. We would, effectively, be in a private virtual reality scenario where what we perceive to be solid objects are actually constructs. It is hard to think of any experiment we could carry out which would reveal this.
Difficulties with Idealism
Other that Solipsism, a difficulty with Idealism is that the external world is a shared one. Our experience of interacting with other minds is described parsimoniously as using material, which follows Physical Laws, as a go-between.
Without that, we would need to postulate an elaborate shared virtual reality machine, such as the Matrix, which behaves in all the ways that the external world appears to behave. There would be no explanation of why it was there or had the structure that it does. Such a move appears to be unnecessary and to raise many more questions than it solves.