This article examines the Nastika Darshanas, the heterodox or Veda-rejecting schools of ancient Indian philosophy, as a counterpart to the more widely discussed six Astika (Vedic-affirming) Darshanas. It clarifies the precise technical meaning of Nastika — rejection of Vedic authority, not atheism per se — and documents genuine scholarly disagreement over how many schools belong in this category, with sources ranging from three to five. It examines Carvaka (Lokayata), the ancient materialist school traditionally associated with Brihaspati, whose foundational Barhaspatya Sutras are lost and survive only in fragmentary reconstructions by scholars including Dakshinaranjan Shastri (1928, 1959) and Ramkrishna Bhattacharya (2002), with Madhavacharya's 14th-century Sarva-Darshana-Samgraha as the dominant, admittedly hostile secondary source. It examines Ajivika, the fatalist school associated with Makkhali Gosala, drawing on the Jain Bhagavati Sutra and the Buddhist Samannaphala Sutta, including genuine scholarly uncertainty over whether Gosala founded the movement or merely led an existing one. It examines Jainism's Anekantavada and Buddhism's doctrine of dependent origination as the two heterodox schools that survived as independent living traditions, and Ajnana, the school of radical skepticism associated with the named historical figure Sanjaya Belatthiputta, documented in the Brahmajala Sutta. The article concludes with a comparative table of the six Astika and five Nastika Darshanas and an honest accounting of the source-bias problem inherent in studying traditions whose own texts did not survive.
Narayan Rout (2026) studied this question.