Vedic Schools Differ: All orthodox schools of Hinduism – Nyaya, Vaisesika, Samkhya, Yoga, Mimamsa and Vedanta – accept the foundational premise of Vedas and Upanishads that “Ātman exists.” Jainism too accepts this premise, though it has its own perspective on what that means. In contrast, both Buddhism and the Charvakas deny that there is anything called as “Ātman, Soul, Self.”
Attaining to individual knowledge of Ātman is the defining theme of the orthodox schools. Hinduism sees Ātman as distinct from the ever-evolving individual personality characterized with Ahamkara (ego or psychological Me-ness), habits, prejudices, desires, impulsiveness, delusions, fads, behaviors, pleasures, sufferings and fears. Human personality and Ahamkara shifts, evolves or changes with time; Ātman is the unchanging, eternal, innermost radiant self that is unaffected by personality or ego, unaffected by ego of others. Ātman is ever-free, never-bound, seeks, realizes and is the realized purpose, meaning, liberation in life.
Self-knowledge comprises the knowledge and understanding of Ātman, what It is versus what It is not.
Below, I discuss several schools so to show the great diversity of thought. In truth, no one knows the answer to the eternal question, “Who? What is God?” While, the several Hindu schools provide very different answers, Hinduism is pluralistic; neither exclusive (fundamental Judea-Christian-Islam) nor inclusive (modern Catholicism). Many paths lead to Divinity!
Vedanta Schools: The Advaita (non-dualist) philosophical schools teach that the “spirit, soul, self” existing within each living entity as fully identical with Ātman and Brahman – the One Universal Soul. Advaita schools maintain that this One Soul connects and exists in all living beings, regardless of species differentiation; there is no distinction, no superior, no inferior, no separate devotee soul (jiva-atma), no separate God soul (Jiva-Brahman). This Oneness unifies all beings, is the divine within, and is the Single Reality. Ātman is self-existent, limitless, and non-dual. Ātman is the Brahman, the Brahman is the Atman, each individual self is not different from the infinite. Ātman is the Universal Principle, an eternal, undifferentiated, self-luminous consciousness.
Human beings function automatically in a state of ignorance of the existence of this Universal Self. Subsequently, each person perceives his or her “Me-ness”as distinct from others, such sense of distinctiveness causing them to act out of impulse, fears, cravings, malice, division, confusion, anxiety, passions, and greed. Conversely, Ātman-knowledge brings one to a state of full awareness, liberation, and freedom, overcoming artifactual dualism, by realizing the divine within oneself, the same divine within others, the non-dual Oneness, that God is in everything, and everything is God.
This identification of individual living beings/souls, or jiva-atmas, with the ‘One Ātman’ is the non-dualistic Advaita Vedanta position. In contrast, devotional sub-schools of Vedanta, such as Dvaita (dualism), differentiate between the individual jiva-atma in living beings and the Supreme Atma (Paramatma).
Dvaita Vedanta calls the Ātman of a Supreme Being, “Paramatman”; holding it different from individual jiva-atma. Dvaita scholars assert that God is the ultimate, complete, perfect, distinct Soul; one that is separate from the incomplete, imperfect jivas (individual souls). Advaita schools believe that Self-knowledge leads to liberation in this life; Dvaita schools believe that liberation is only possible in the afterlife, as communion with God, and only through the grace of God (if not, then one’s jiva-atma is reborn). God created individual souls, but, each individual soul never was and never will become one with God; the best it can do is to experience bliss by getting infinitely close to God. The Dvaita schools, therefore, in contrast to monistic position of Advaita, advocate a version of monotheism wherein Brahman is made synonymous with Vishnu (or Narayana), distinct from numerous individual jiva-atmas.
As a side note, the post-Lurianic Kabbalist schools are theologically quite close to the Dvaita schools of India. See http://www.kab.tv.
Vaiśe ika school: The Vaisheshika school of Hinduism, in sharp contrast with the Vedanta schools, present non-theistic theories of atomistic naturalism. They posit that Ātman is one of the four eternal non-physical substances without attributes, the other three are kala (time), dik (space) and manas (mind). Time and space are eka (one), nitya (eternal), and vibhu (all pervading). Time and space are indivisible in actuality; though, human minds prefer to divide them so to comprehend past, present, future, the relative location of other objects and beings, and establish directions and coordinates in the universe. In contrast to these characteristics of time and space, Vaiśe ika scholars considered Ātman to be many, eternal, independent and spiritual substances that cannot be reduced or inferred from other three non-physical and five physical dravya (substances). Mind and sensory organs are instruments, while consciousness is the domain of “atman, soul, self.”
Nyaya school: The Nyaya scholars defined Ātman as an imperceptible substance that is the substrate of human consciousness, manifesting itself with or without qualities such as desires, feelings, perception, knowledge, understanding, errors, insights, sufferings, bliss and others. The Nyaya school not only refined the theory of Ātman, contributing to Hindu philosophy in a number of ways. To the Hindu theory of Ātman, the contributions of Nyaya scholars were twofold. One, they went beyond holding it as “self evident” and offered rational proofs, consistent with their epistemology, in their debates with Buddhists, that “Ātman exists.” Second, they developed theories on what “Atman is and is not.” As proofs for the proposition “Self, Soul exists,” for example, Nyaya scholars argued that personal recollections and memories of the form “I did this so many years ago” implicitly presume that “there is a Self that is substantial, continuing, unchanged and existent.”