Acosmism
Acosmism, held in contrast or equivalent to pantheism, denies the reality of the universe, seeing it as ultimately illusory, and only the infinite unmanifest Absolute as real. Conceptual versions of Acosmism are found in eastern and western philosophies.
In Eastern philosophy
The concept of Maya in the non-dual Advaita Vedanta school of Hinduism is a form of acosmism. Maya means "illusion, appearances". The universe is considered to be Māyā, however this does not mean the universe is considered as unreal. Wendy Doniger explains, "to say that the universe is an illusion is not to say that it is unreal; it is to say, instead, that it is not what it seems to be, that it is something constantly being made. Māyā not only deceives people about the things they think they know; more basically, it limits their knowledge to things that are epistemologically and ontologically second-rate."In the Vedanta school of Hinduism, the perceived world is Maya that hides the Absolute and Ultimate Reality. The human mind constructs a subjective experience, states Vedanta, which leads to the peril of misunderstanding Maya as well as interpreting Maya as the only and final reality. Vedantins assert the "perceived world including people are not what they appear to be, there is more to them than their perceived physical forms". Māyā is that which manifests, perpetuates a sense of false duality. This manifestation is real, but it obfuscates and eludes the hidden principles and true nature of reality. Vedanta holds that liberation is the unfettered realization and understanding of these invisible principles, primarily that the individual Self is the same as the Self in others and the Self in everything.
Michael Comans says that the purpose of Advaita Vedanta as stated in the Māṇḍūkya Upaniṣhad is to reveal that there is a single Absolute Reality which underlies the cosmos, yet is inherently acosmic, and which constitutes the essential “core”, or “self” of all beings. The Upanishad calls this Reality by the name Brahman and it explicitly says that Brahman is identical to the self.
Advaita Vedanta school is best described as monistic, absolute idealism, while Dvaita Vedanta school as pluralistic idealism. Both have elements of ontological acosmism, where the material aspect of cosmos is considered an "illusion, appearance, incomplete reality" compared to that "which is spiritual, eternal, unchanging". In Advaita Vedanta philosophy, there are two realities: Vyavaharika and Paramarthika. Māyā is a fact in that it is the appearance of phenomena. Brahman is held by Advaitins as the metaphysical truth. The perceived world, Māyā is true in epistemological and empirical sense; however, Māyā is not considered by Vedantins as the metaphysical and spiritual truth. The spiritual truth is the truth forever, while what is empirical truth is only true for now. Since Māyā is the perceived material world, it is true in perception context, but is "untrue" in spiritual context of Brahman. True Reality, to Advaita scholars, includes both Vyavaharika and Paramarthika, the Māyā and the Brahman. The goal of spiritual enlightenment, state Advaitins, is to realize one's soul as same as Cosmic Soul, realize the eternal, fearless, resplendent Oneness.
Advaita Hinduism and Buddhism have both been called as examples of acosmism. Other scholars state Buddhism cannot be accurately classified as a philosophy based on acosmism, and that Advaita Vedanta is not acosmism either.