cArVaka dars’ana is the philosophy of the sweet speaking atheists of Ancient India. It is also called lOkAyatamata. Some people consider the son of lOka, a certain bRhaspati, as the founder of this system.
These people accept only pratyakSa pramANa (seeing is believing) as a valid source of knowledge. They reject anumAna or inference.
The dhUrta (crass) cArvAkAs accept only kAma and artha as puruSArthAs. ie desire and wealth in order to fulfil desires are considered the only human goals.
The sus’ikshita (cultured) cArvAkAs accept dharma also as a puruSArtha.
They accept only 4 tattvAs or bhUtAs – earth, air, water and fire. They do not accept AkAs’a (sky, space, ether) tattva.
At least in the rejection of AkAs’a tattva they have been vindicated by the Michelson Morley Experiment!!
An they don’t believe that there is a God or an Atman. They reject vEdAs and dharmas’AstrAs.
At any point in time the cArvAkAs have always constituted a large part of the population.