Schools of Indian Philosophy

Buddhism and Jainism: Beliefs and Sects already covers Buddhist and Jain philosophy in depth. This note covers the six orthodox (Astika) schools that accept the Vedas' authority, plus Charvaka, the heterodox (Nastika) school that rejects it, the specific classification distinction this chapter tests directly.

Orthodox versus heterodox: one classifying question

India's classical philosophical schools (darshanas) are sorted first by a single test: whether a school accepts the Vedas as a valid source of authoritative knowledge. Schools that do are Astika (orthodox); schools that reject Vedic authority, chiefly Charvaka, along with Buddhism and Jainism (both covered separately in this site's own dedicated note), are Nastika (heterodox). This is a classification about scriptural authority specifically, not a judgement about belief in God as such, since several orthodox schools (Sankhya and early Mimamsa among them) do not centrally require a creator God either.

The six orthodox schools, in three traditional pairs

The six orthodox schools are traditionally grouped into three complementary pairs, each pair sharing closely related concerns.

Nyaya-Vaisheshika: Nyaya, founded by the sage Gautama, is built around logic and epistemology, a systematic, rational method for establishing valid knowledge and correct reasoning. Vaisheshika, founded by Kanada, is a school of physics and metaphysics built on atomism (paramanu-vada): it holds that all physical matter is ultimately composed of indivisible, eternal particles (paramanu, "atoms"), which combine first in pairs (dvyanuka) and then in larger combinations (tryanuka) to build up the visible world, a strikingly early atomic theory of matter developed centuries before its counterpart emerged in Western science.

Sankhya-Yoga: Sankhya, founded by the sage Kapila, is built on a dualism between two fundamental, independent principles: Purusha (pure consciousness, the observing self) and Prakriti (nature, or matter, the active, evolving principle), with the whole observable universe understood as an evolution of Prakriti while Purusha remains a separate, untouched witness. Yoga, systematised by Patanjali in the Yoga Sutras, shares Sankhya's basic Purusha-Prakriti framework but adds a practical discipline for realising that separation directly: Patanjali defines yoga itself as chitta vritti nirodhah, the cessation of the mind's own fluctuations, achieved through the eight-limbed path (Ashtanga Yoga): yama, niyama, asana, pranayama, pratyahara, dharana, dhyana and samadhi, moving from ethical restraint through physical and breath discipline to progressively deeper states of meditative absorption.

Mimamsa-Vedanta: (Purva) Mimamsa, founded by Jaimini, focuses on the correct interpretation and ritual application of the Vedic texts themselves, particularly their instructions for sacrifice and duty (dharma), treating precise textual analysis as the path to right action. Vedanta ("the end of the Vedas"), systematised by Vyasa (traditionally credited with compiling the Brahma Sutras) and drawing on the Upanishads, is the most explicitly metaphysical of the six, holding, in its dominant (Advaita, non-dualist) form, that the world as ordinarily perceived is not ultimately real and that the only true reality is Brahman, the single, undivided absolute that the individual self (Atman) is, at the deepest level, not separate from at all.

Charvaka: the heterodox materialist counterpoint

Charvaka (also called Lokayata) stands apart from all six orthodox schools by rejecting Vedic authority, the existence of an afterlife or soul, and any form of knowledge not directly verifiable by the senses, accepting only direct perception as a valid source of knowledge and dismissing inference and scriptural testimony as unreliable. Its ethical outlook followed directly from this materialism: since neither an afterlife nor a soul could be empirically verified, Charvaka held that a person should pursue pleasure and avoid pain in this one, sole life, without deferring to promised rewards or punishments in a hereafter, making it the most explicitly this-worldly and empiricist of all the classical Indian philosophical schools, and the standard named example whenever a question tests the orthodox-versus-heterodox distinction directly.

Quick revision points

• Astika (orthodox) schools accept Vedic authority; Nastika (heterodox) schools reject it (Charvaka, Buddhism, Jainism). This is a classification by scriptural authority, not by belief in God.
• Nyaya (Gautama): logic and epistemology, valid reasoning. Vaisheshika (Kanada): atomism, matter built from indivisible paramanu combining into dvyanuka and tryanuka.
• Sankhya (Kapila): dualism of Purusha (consciousness) and Prakriti (nature/matter). Yoga (Patanjali, Yoga Sutras): shares Sankhya's framework, adds the Ashtanga Yoga eight-limbed practical path (yama, niyama, asana, pranayama, pratyahara, dharana, dhyana, samadhi) to still the mind's fluctuations.
• (Purva) Mimamsa (Jaimini): correct interpretation of Vedic ritual and dharma. Vedanta (Vyasa, Brahma Sutras, Upanishads): in its Advaita form, holds Brahman as the sole ultimate reality, with Atman not ultimately separate from it.
• Charvaka (Lokayata): heterodox materialism, accepts only direct sense-perception as valid knowledge, rejects afterlife/soul, advocates pursuing pleasure and avoiding pain in this one life; the standard example of a Nastika school.