The six astika (Veda-accepting) schools of Hindu philosophy. Three complementary pairs: Nyaya + Vaisheshika (logic + atomism), Sankhya + Yoga (dualism + path), Purva Mimamsa + Vedanta (karma-kanda + jnana-kanda).
The Six Astika Schools
1 · Nyaya · न्याय — Logic + epistemology
Founder: Maharshi Gautama (Akshapada) · Era: 6th century BCE · Primary text: Nyaya Sutras.
_Liberation comes through correct knowledge — and correct knowledge requires a science of valid means of knowing._
The first systematic Indian logic. Defines four pramanas (means of valid knowledge): perception, inference, comparison, verbal testimony. Codifies the five-membered syllogism. Argues that misery arises from false belief; demolish false belief through rigorous inference and liberation follows. Classical commentator: Vatsyayana (Nyaya-bhashya, 5th c.).
2 · Vaisheshika · वैशेषिक — Atomism + categories
Founder: Maharshi Kanada (Uluka) · Era: 6th century BCE · Primary text: Vaisheshika Sutras.
_Everything that exists falls into one of six (later seven) padarthas, and matter ultimately consists of indivisible anu (atoms)._
Sister-school to Nyaya. Where Nyaya focuses on means of knowing, Vaisheshika focuses on the objects of knowing — proposing six fundamental categories (dravya, guna, karma, samanya, vishesha, samavaya) that classify every possible entity. Anticipated modern atomic theory by 2,500 years. Classical commentator: Prashastapada (5th c.).
3 · Sankhya · साङ्ख्य — Dualism — purusha + prakriti
Founder: Maharshi Kapila · Primary text: Sankhya Karika of Ishvara Krishna (4th c. CE) — the original Sankhya Sutras attributed to Kapila are lost.
_Reality has two independent principles — purusha (witness-consciousness) and prakriti (matter with three gunas). Suffering ends when the witness is no longer mistaken for the witnessed._
Indian dualism. Prakriti unfolds into 23 tattvas (mahat → ahankara → manas → 10 indriyas → 5 tanmatras → 5 mahabhutas). Liberation = viveka (discrimination) between purusha and prakriti. Atheistic in classical formulation but folded into theism by every later Vedantin. Classical commentator: Vachaspati Mishra (9th c.).
4 · Yoga · योग — Path — citta-vritti-nirodha
Founder: Maharshi Patanjali · Era: 2nd century BCE · Primary text: Yoga Sutras.
_Yoga is the stilling of the modifications of the mind. The witness, freed from identification with the mind, abides in its own nature._
Builds on Sankhya metaphysics but adds an Ishvara. Codifies the eight-limbed (ashtanga) path — yama, niyama, asana, pranayama, pratyahara, dharana, dhyana, samadhi. Distinguishes types of samadhi (savikalpa vs nirvikalpa) and yields the famous "yogah chitta-vritti-nirodhah" definition in 196 sutras. Classical commentator: Vyasa (~5th c.).
5 · Purva Mimamsa · पूर्व मीमांसा — Vedic ritual + dharma
Founder: Maharshi Jaimini · Era: 3rd century BCE · Primary text: Mimamsa Sutras.
_The Veda is eternal and self-validating. Correct performance of Vedic karma (ritual) produces apurva (unseen merit) that ripens as heaven._
Focuses on the karma-kanda (action portion) of the Veda — the Brahmanas and Samhitas. Develops a precise grammar of injunctions (vidhi), prohibitions (nishedha), and arthavada (eulogy). The classical defender of Vedic ritual orthodoxy. Classical commentators: Shabara, Kumarila Bhatta, Prabhakara.
6 · Uttara Mimamsa / Vedanta · वेदान्त — Brahman + Self — jnana-kanda
Founder: Maharshi Badarayana (Veda Vyasa) · Primary text: Brahma Sutras.
_Brahman is the sole reality. The individual self (jiva) is non-different from Brahman; ignorance (avidya) alone causes the appearance of separation. Liberation = realisation of this identity._
Focuses on the jnana-kanda (knowledge portion) of the Veda — the Upanishads. Codified in 555 sutras of Badarayana. Three classical sub-schools split on the jiva-Brahman relation: Advaita (Shankara — non-dualism), Vishishtadvaita (Ramanuja — qualified non-dualism), Dvaita (Madhva — dualism). The dominant darshana of post-classical Hindu thought.
Sub-schools of Vedanta
Advaita — Adi Shankaracharya, 8th c. CE. Brahman alone is real; the world is mithya (apparent). Jiva = Brahman. Liberation through jnana.
Vishishtadvaita — Ramanujacharya, 11th c. CE. Brahman (Vishnu) is real and so are the souls and the world — but they exist as His body. "Qualified non-dualism." Liberation through prapatti (surrender) + bhakti.
Dvaita — Madhvacharya, 13th c. CE. Vishnu, jivas, and matter are eternally distinct. Strict dualism. Liberation through bhakti.
Dvaitadvaita — Nimbarkacharya, 13th c. CE. Difference + non-difference (bhedabheda). Krishna + Radha as the highest principle.
Shuddhadvaita — Vallabhacharya, 15th c. CE. Pure non-dualism without illusion. Brahman = Krishna. Liberation through pushti-marga (the path of grace).
Achintya Bhedabheda — Sri Chaitanya Mahaprabhu, 16th c. CE. "Inconceivable difference and non-difference." Krishna is supreme; bhakti via the maha-mantra. Foundational for the Gaudiya tradition + ISKCON.
The Three Nastika Schools
"Nastika" = "the Veda is not authoritative." Listed for context — they coexisted with the astika schools in Indian philosophical debate.
Buddhism — Gautama Buddha (~5th c. BCE). Suffering is, has cause, can end, by the Eightfold Path. No permanent soul (anatta).
Jainism — Tirthankara Mahavira (~6th c. BCE; 24th tirthankara). Plural eternal souls (jivas) trapped by karma-matter. Liberation through ahimsa, satya, asteya, brahmacharya, aparigraha.
Charvaka / Lokayata — Brihaspati / Charvaka lineage (~6th c. BCE). Strict materialism. Only perception is valid pramana. No soul, no afterlife, no karma.