Sarvepalli Radhakrishnan argues that one unifying conviction of the six Brahmanical darsanas, the “orthodox systems” of classical Hindu thought, was an opposition to “the skepticism of the Buddhists” (Sourcebook in Indian Philosophy, 354). What does that mean, exactly?
Well, consider this profoundly Cartesian moment in Nagarjuna’s (2nd c. AD) “Twenty Verses on the Great Vehicle” “As perception takes place in a dream which when awakened disappears, so it is with sleeping in the darkness of ignorance: when awakened, transmigrations have no more” (XVII, Sourcebook, 339). Rather than attempting, with Descartes, to extricate himself from the skeptical trap, Nagarjuna embraces the chilling intuition of the likeness between dreaming and waking life — the world simply is a dream, a mind-dependent phantasm. Shortly before, he cautions that our entanglement in this illusory dream state is the self-inflicted source of suffering: “As a stupid child making a muddy pool is himself drowned in it, so are sentient beings drowned in the mire of false discrimination and unable to get out of it” (XI, 339).
In an earlier text, this skepticism has a strikingly Humean flavor: just as “the word ‘chariot’ is but a way of counting, term, appellation, convenient designation, and name for pole, axle, wheels, chariot-body, and banner staff,” so too “in exactly the same way…[the name] Nagasena is but a way of counting, term, appellation, convenient designation, and name for the hair of my head…brain of the head, form, sensation, perception, the predispositions, and consciousness” (284). What we naively take to be unities (in Aristotelian terms, “secondary substances” unified by formal causes) are in fact merely imaginative groupings of a generic “stuff.”