Where can I read about the debates of adi shankara and charvakas?

Question

Adi Shankara was a great philosopher. He debated many people. He might also have debated charvakas. So where can I find it.

Answer 1

Please see Brahma Sutra Bhasya.

53. Some (deny) (the existence) of an Atman (separate from the body), (for It) exists (only) when there is a body.

This Sutra gives the view of the Charvakas or materialists, who deny the existence of an Atman other than the body. They say that man is only a body, having consciousness for its quality, and that consciousness is like the intoxicating property that is produced when certain materials are put together, none of which singly is intoxicating. They arrive at this conclusion in this way. Consciousness is seen to exist only when there is a body. Independent of the body it is nowhere experienced. Hence it is only a quality of the body. Therefore, there is no separate Self in this body.

54. But not (so); (a Self) separate (from the body does exist), for (consciousness) does not exist even when there is the body (after death); as in the case of cognition.

This Sutra refutes the view expressed in the previous one. Consciousness cannot be a quality of the body, for we do not find consciousness in a body; after a person dies. So this consciousness is a quality of something different from and residing in the body. Again the Charvakas also accept that the cognizer is different frejm the thing cognized. If so, since we experience our body, we who cognize it must be different from our body; and this thing which cognizes this body of ours is the Self, and consciousness is a quality of this Self, rather its nature.

The argument of the chArvAka uses the logical reasoning called ‘anvaya-vyatireka’. When the body is present, consciousness is present (anvaya). When the body is absent, consciousness is absent (vyatireka). Therefore the body is the same as consciousness.

This leads to the question whether consciousness is produced by the brain as claimed by the charvakas and other materialists or whether consciousness is independent of the brain.

In vedanta sutras, he says that there is a distinction between consciousness and the body because the former may be absent even while the latter continues to exist. Vedanta argues that on the death of the brain, only the consciousness reflected by the brain disappears while it continues to exist. A defect in the reflection does not affected the original just a crack in the mirror does not affect the object reflected in the mirror. Though you require a radio to listen to the airwaves, the airwaves are independent of the radio. Thus it cannot be concluded that consciousness is an attribute of the body/brain.

Shankara adds that, while such things as the form and shape of the body can be seen by another person, qualities such as consciousness, memory and life itself cannot be perceived, only inferred. As inference is not a pramana for charvakas, he says one can not argue further. We cannot say that, because we do not experience something, it does not exist. Just like we cannot conclude that something is absent because we do not experience it, we certainly cannot also conclude that it is present. Thus, we have to rely on shabda pramana to say that consciousness exists in the absence of the body.

There are many other arguments of the charvakas regarding other issues and most of them are refuted in advaita. Please see the book Sarva Darshana Samgraha