Hindu philosophy began in the period of the Upanishads (900-500 B.C.), but systematic philosophical elaboration did not appear until several centuries later. Philosophical tenets were presented in the form of aphorisms or sutras, intended to serve as an aid to memory and a basis for oral elaboration. Their extreme conciseness presupposes an oral or written commentary, and the traditions developed through successive layers of commentarial tradition. Although all six schools of classical Hindu philosophy accepted the authority of the Veda, they had widely differing philosophical positions; they developed in competition not only with one another, but also with the so-called heterodox schools, which rejected the authority of the Veda: Buddhism, Jainism, the Ajivikas or skeptics, and the materialist Carvaka school.
Nyaya, traditionally founded by Akshapada Gautama (6th cent. B.C.), is a school of logic and epistemology that defined the rules of debate and canons of proof. Its views were accepted with modification by most of the other schools. The atomist school, Vaisheshika, founded by Kanada (3d cent. B.C.), analyzed reality into six categories: substance, quality, activity, generality, particularity, and inherence. The universe is made up of nine kinds of substance: earth, water, light, air, ether, time, space, soul (or self), and mind.
The Samkhya school, founded by Kapila (6th cent. B.C.), admits two basic metaphysical principles, purusha (soul) and prakriti (materiality). Prakriti consists of three gunas or qualities: sattva (light or goodness), rajas (activity or passion), and tamas (darkness or inertia). When these constituents are in equilibrium, prakriti is static. However, disturbance of the equilibrium initiates a process of evolution that ultimately produces both the material world and individual faculties of action, thought, and sense. The purusha appears to be bound to prakriti and its modifications and may become free only through the realization that it is distinct from prakriti. Early versions of Samkhya, now lost, may have been theistic, but the classical system does not include God. The yoga school expounded by Patanjali (2d cent. B.C.) accepts Samkhya metaphysics to explain the validity of yogic processes described in the Yoga Sutras and also accepts the concept of an Ishvara, God or supreme soul. Yoga is defined as "cessation of the modifications of consciousness" and is achieved by an eight-stage discipline of self-control and meditation.
The Purva Mimamsa school, founded by Jaimini (2d cent. B.C.), set forth sophisticated principles for interpreting the Veda, which was regarded as entirely composed of injunctions to ritual action. Its epistemology and theory of meaning were constructed to show that the words of the Veda had eternal and intrinsic validity. The different schools of Uttara Mimamsa or Vedanta are all based on the Upanishads and the Brahma-Sutras of Badarayana (c.200 B.C.-A.D. 200), but differ in their concepts of God, world, soul, and the relation between them.
See F. M. Müller, The Six Systems of Indian Philosophy (1899, repr. 1963); S. N. Das Gupta, History of Indian Philosophy (4 vol., 1922-55); S. Radhakrishnan and C. A. Moore, Source Book in Indian Philosophy (1957); K. H. Potter, Presuppositions of India's Philosophies (1963) and Guide to Indian Philosophy (1988); A. Embree, The Hindu Tradition (1972) and, with S. Hay, ed., Sources of Indian Tradition (2 vol., 1988).
In Hindu history, the distinction of these six schools was current in the Gupta period "golden age" of Hinduism. With the disappearance of Vaisheshika and Mimamsa, it was obsolete by the later Middle Ages, when the various sub-schools of Vedanta (Dvaita "dualism", Advaita "non-dualism" and others) began to rise to prominence as the main divisions of religious philosophy. Nyaya survived into the 17th century as Navya Nyaya "Neo-Nyaya", while Sankhya gradually lost its status as an independent school, its tenets absorbed into Yoga and Vedanta.
"These two are regarded in India as twins, the two aspects of a single discipline. provides a basic theoretical exposition of human nature, enumerating and defining its elements, analyzing their manner of co-operation in a state of bondage (bandha), and describing their state of disentanglement or separation in release while Yoga treats specifically of the dynamics of the process for the disentanglement, out outlines practical techniques for the gaining of release, or 'isolation-integration' (kaivalya).
The foundational text of the Yoga school is the Yoga Sutras of Patanjali, who is regarded as the founder of the formal Yoga philosophy. The Sutras of the Yoga philosophy are ascribed to Patanjali, who may have been, as Max Müller explains, "the author or representative of the Yoga-philosophy without being necessarily the author of the Sutras.
Nevertheless, Nyaya was seen by its followers as more than logical in its own right. They believed that obtaining valid knowledge was the only way to gain release from suffering, and they took great pains to identify valid sources of knowledge and distinguish these from mere false opinions. According to Nyaya, there are exactly four sources of knowledge: perception, inference, comparison, and testimony. Knowledge obtained through each of these is either valid or invalid. Nyaya developed several criteria of validity. In this sense, Nyaya is probably the closest Indian equivalent to analytic philosophy. The later Naiyanikas gave logical proofs for the existence and uniqueness of Ishvara in response to Buddhism, which, at that time, was fundamentally non-theistic. An important later development in Nyaya was the system of Navya-NyÄya.
Although the Vaisheshika school developed independently from the Nyaya, the two eventually merged because of their closely related metaphysical theories. In its classical form, however, the Vaisheshika school differed from the Nyaya in one crucial respect: where Nyaya accepted four sources of valid knowledge, the Vaisheshika accepted only two—–perception and inference.
The Mimamsa accepted the logical and philosophical teachings of the other schools, but felt they did not sufficiently emphasize attention to right action. They believed that the other schools of thought that aimed for release (moksha) did not allow for complete freedom from desire and selfishness, because the very striving for liberation stemmed from a simple desire to be free. According to Mimamsa thought, only by acting in accordance with the prescriptions of the Vedas may one attain salvation.
The Mimamsa school later shifted its views and began to teach the doctrines of Brahman and freedom. Its adherents then advocated the release or escape of the soul from its constraints through enlightened activity. Although Mimamsa does not receive much scholarly attention, its influence can be felt in the life of the practising Hindu, because all Hindu ritual, ceremony, and law is influenced by this school.
While the traditional Vedic rituals continued to be practised as meditative and propitiatory rites, a more knowledge-centered understanding began to emerge. These were mystical aspects of Vedic religion that focused on meditation, self-discipline, and spiritual connectivity, more than traditional ritualism.
The more abstruse Vedanta is the essence of the Vedas, as encapsulated in the Upanishads. Vedantic thought drew on Vedic cosmology, hymns and philosophy. The Brihadaranyaka Upanishad is believed to have appeared as far back as 3,000 years ago. While thirteen or so Upanishads are accepted as principal, over a hundred exist. The most significant contribution of Vedantic thought is the idea that self-consciousness is continuous with and indistinguishable from consciousness of Brahman.
The aphorisms of the Vedanta sutras are presented in a cryptic, poetic style, which allows for a variety of interpretations. Consequently, the Vedanta separated into six sub-schools, each interpreting the texts in its own way and producing its own series of sub-commentaries. Four of them are given here.