In the outlines of Indian philosophy, Charvaka is classified as a "heterodox" (nastika) system, the same classification as is given to Buddhism and Jainism. While this branch of Indian philosophy is not considered to be part of the six orthodox schools of Hinduism, it is a remarkable testimony of the materialistic movement within Hinduism.
According to research by eminent scholars it has been found that Charvaka philosophy is co-eval with Buddhism and in 500 B.C. it meant 'scepticism'. Apart from the account of Charvaka philosophy found in the Rig Veda, certain amount of material is also contained in the Chhandogya Upanishad, the Mahabharata, Vatsyayana's Nyayabhasya (2.1.37; 3.2.35), Sridhara's Nyayakandali, Jayanta's Nyayamanjari, Udayana's Nyayakusumanjali (1.15), Prabhachandra's Nyayakumudachandra, Shankara's Sharirakabhasya (1.1.1; 2.2.2; 3.3. 53-54) and Vachaspati's Bhamati (3.3.53). Further research has proved that during the Mauryan period the Charvaka philosophy had grown out of generic skepticism but at the same time the exact date of Charvaka philosophy cannot be ascertained before the 6th century. It has also been found that the Brhaspatya Sutras were written during the reign of the Mauryas.
The Charvaka Philosophy is called the Lokayata because the philosophy believes that only this world or the 'lok' is the truth. They believe that whatever is arrived by the means of direct perception is the ultimate truth. Whatever is not perceivable is non-existent because of the simple reason that it cannot be perceived. The proponents of this school of thought believed that since sense perception is the only form of knowledge therefore in that case matter becomes the only reality. It is only matter that is cognizable with the help of senses. According to the philosophy the ultimate principles are the four elements. The four elements are earth, water, air and fire. These elements according to them are eternal and can explain the development from a protozoan to a philosopher. In fact they said that intelligence is also the modification of the four elements and intelligence is perished when the element from which it rises gets dissolved. Even consciousness says the Charvaka philosophy is produced after combining the four elements. Thought is also the function of matter. They believe that there is no world other than this. There exists neither hell nor heaven. For them religion is a foolish aberration and God is not necessary to account for the world. Thus with an audacious dogmatism the Charvaka philosophy has swept the world clean of all its values and has put down belief in the Almighty as a symbol of mendaciousness, weakness and cowardice.
The Charvakas have emphasised that pleasure and pain are the central themes of life and it is not possible to separate life from all these. They have also claimed that virtue is nothing more than a delusion and enjoyment is the only reality. The Charvaka School of Thought believed that life is the end of life. Unlike the Upanishads the Charvaka or the materialist philosophy asserts the doctrines of uncontrolled-energy, self-assertion and reckless disregard for authority.
Charvaka philosophy strictly believes in perception as the one source of valid knowledge. Hence, everything is pivoted according to this principle. Metaphysics or the knowledge of being and knowing is also rigidly adhered with perception as the source of knowledge. According to Charvakas, atman is not a separate entity, as one can never 'see' atman. It is consciousness that makes one grasps the reality of everything worldly. Hence, the mind, the physical body, or the world one dwells in - everything depends on perception and the realisation by the consciousness.
Charvakas believe not in the notion of stringent philosophy, but in liberal beliefs. Hence, they refute most of the already-established rules in the context of Indian philosophy. The prime importance is laid on the likes and dislikes of humans. As a result, Charvakas believe in the perceived knowledge of the present life, and not in rebirth and past life. According to them good deed is not much necessary to perform in one's lifetime, as is instructed by the crafty priests. The basic thought of the Charvakas is to obtain worldly pleasure by making merry, as there is no hell where one can be hurled.
Hence, it can be concluded saying that the materialist philosophy had a lot to do with regard to the repudiation of old system of religion and custom of magic. The Charvaka Philosophy is in fact a man's return to his own spirit and rejection of all those which are external and foreign. It also says that nothing needs to be accepted by an individual which do not find its place in the way of reason.