Metaphysics is the theory of reality. The Carvaka theory of reality follows from the epistemological conclusion just discussed. If perception is the only reliable source of knowledge, we can rationally assert only the reality of perceptible objects.
God, soul, heaven, life before birth or after death, and any unperceived law (like adrsta) cannot be believed in, because they are all beyond perception.
Material objects are the only objects whose existence can be received and whose reality can be asserted. The Carvakas, thus, come to establish materialism or the theory that matter is the only reality.
1. The World is made of Four Elements
Regarding the nature of the material world, most other Indian thinkers hold that it is composed of five kinds of elements (paricabhuta), namely, ether (akasa), air (vayu), fire (Agni), water (ap) and earth (ksiti).
But the Carvakas reject ether, because its existance cannot be perceived; it has to be inferred. The material world is, therefore, held to be composed of the four perceptible elements.
Not only non-living material objects but also living organisms, like plants and animal bodies, are composed of these four elements, by the combination of which they are produced and to which they are reduced on death.
2. There is no Soul
gut it may be asked, even if perception is the only source of knowledge, do we not have a kind of preception, called internal, which gives an immediate knowledge of our mental states?
And do we not perceive in these consciousness which is nowhere to be perceived in the external material objects?
If so, does it not compel us to believe that there is in us some non-material substance whose quality is consciousness the substance which is called soul or spirit (atma)?
The Carvakas admit that the existence of consciousness is proved by perception. But they deny that consciousness is the quality of any unperceived non-material or spiritual entity.
As consciousness is perceived to exist in the perceptible living body composed of the material elements, it must be a quality of this body itself. What people mean by a soul is nothing more than this conscious living body (caitanya-visista deha eva atma).
The non-material soul is never perceived. On the contrary, we have direct evidence of the identity of the self with the body in our daily experiences and judgments like, ‘I am fat,’ ‘I am lame’, ‘I am blind’. If the ‘I’, the self, were different from the body, these would be meaningless.
But the objection may be raised: we do not perceive consciousness in any of the four material elements. How can it then come to qualify their product, the body?
In reply the Carvaka points out that, qualities not present originally in any of the component factors may emerge subsequently when the factors are combined together.
For example, betel leaf, lime and nut, none of which is originally red, come to acquire a reddish tinge then chewed together.
Or, even the same thing placed under a different condition may develop qualities originally absent. For example, molasses (guda), originally non-intoxicant, becomes intoxicant when allowed to ferment.
In a similar way, it is possible think that the material elements combined in a particular way give rise to the conscious living body. Consciousness is an epiphenomenon or bye-product of matter; there is no evidence of its existence independent of the body.
If the existence of a soul apart from the body is not proved, there is no possibility of proving its immortality. On the contrary, death of the body means the end of the individual.
All questions about previous life, after-life, rebirth, enjoyment of the fruits of actions in heaven or hell, therefore, become meaningless.
3. There is no God
God, whose existence cannot be perceived, fares no better than the soul. The material elements produce the world, and the supposition of a creator is unnecessary.
The objection may be raised: can the material elements by themselves give rise to this wonderful world? We find that even the production of an object like an earthen jar requires, in addition to clay which is its material cause, a potter who is the efficient cause that shapes the material into the desired form.
The four elements supply only the material cause of the world. Do we not require an efficient cause, like God, as the shaper and designer who turns the material elements into this wonderful world?
In reply, the Carvaka states that the material elements themselves have got each its fixed nature (svabhava). It is by the natures and laws inherent in them that they combine together to form this world.
There is thus no necessity for God. There is no proof that the objects of the world are the products of any design. They can be explained more reasonably as the fortuitous products of the elements. The Carvakas, therefore, prefer atheism.
Insofar as this Carvaka theory tries to explain the world only by nature, it is sometimes called naturalism (svabhavavada).
It is also called mechanism (yadrccha-vada), because it denies the existence of conscious purpose behind the world and explains it as a mere mechanical or fortuitous combination of elements.
The Carvaka theory on the whole may also be called positivism, because it believes only in positive facts or observable phenomena.