Indian philosophy is usually told around transmigration and liberation; yet the same tradition harboured, for centuries, a school that rejected all of it. Charvaka — under its older name Lokayata, "belonging to this world" — appeared in the debating culture of the Ganges basin in the age of the Buddha and Mahavira.

Its claim begins with epistemology: the only valid source of knowledge is perception (pratyaksha). Neither inference nor testimony can yield certainty, because the invariable connection that carries us "from smoke to fire" has itself never been perceived; it can only be defended by yet another inference. The argument overlaps strikingly with David Hume's critique of induction two thousand years later. The same standard is turned on the Vedas: scripture too is testimony, and therefore not an authority.

Its metaphysics follows from that standard. There are only four elements: earth, water, fire, and air. Consciousness is not a separate substance but a property that emerges when these combine in a certain order — in the school's famous analogy, as ingredients that do not intoxicate on their own acquire an intoxicating power once fermented. When the body disperses, consciousness ends; there is no other world, no karmic debt, no liberation.

Charvaka's own books are lost; of the sutras attributed to Brihaspati only quotations survive. We know the school almost entirely through opponents writing to refute it — Nyaya, Vedanta, Buddhist, and Jain authors — so the crude hedonism ascribed to it is most likely a caricature. Its existence matters nonetheless: it shows Indian thought to have been not a religious whole but a genuine field of argument, materialism included.