The Six Astika Darshanas and the Nastika Schools

Classical Indian philosophy is traditionally organized around six orthodox schools, or astika darshanas, each grounded in its own sutra collection. Nyaya, founded on Gautama's Nyaya Sutras, develops logic, epistemology through a theory of pramana (valid means of knowledge), and a theistic proof for Ishvara as efficient cause of the universe. Vaisheshika, founded on Kanada's Vaisheshika Sutras, develops an atomist physics organized around a category (padartha) ontology. Samkhya, systematized in Ishvarakrishna's Samkhya Karika, posits a dualism of Purusha, consciousness, and Prakriti, matter, evolving through twenty-five tattvas. Yoga, systematized in Patanjali's Yoga Sutras, adopts Samkhya's metaphysics while adding a practical eight-limbed discipline, ashtanga yoga, and accepting Ishvara as a special Purusha. Purva Mimamsa, founded on Jaimini's Mimamsa Sutras, focuses on the correct interpretation of Vedic ritual injunctions (vidhi) and defends the eternality and authorlessness of the Veda. Uttara Mimamsa, or Vedanta, founded on Badarayana's Brahma Sutras, interprets the Upanishads' teaching on Brahman and branches into Advaita, Vishishtadvaita, Dvaita, and other sub-schools.