Dhurtta Carvakas denied the existence of soul and regarded consciousness and life as products of bodily changes; there were other Carvakas called Sus'ik@sita Carvakas who admitted the existence of soul but thought that it was destroyed at death. The Buddhists also denied the existence of any permanent self. The naiyayikas ascertained all the categories of metaphysics mainly by such inference as was corroborated by experience. They argued that since consciousness, pleasures, pains, willing, etc. could not belong to our body or the senses, there must besome entity to which they belonged; the existence of the self is not proved according to Nyaya merely by the notion of our self-consciousness, as in the case of Mima@msa, for Nyaya holds that we cannot depend upon such a perception, for it may be erroneous. It often happens that I say that I am white or I am black, but it is evident that such a perception cannot be relied upon, for the self cannot have any colour. So we cannot safely depend on our self-consciousness as upon the inference that the self has to be admitted as that entity to which consciousness, emotion, etc. adhere when they are produced as a result of collocations. Never has the production of atman been experienced, nor has it been found to suffer any destruction like the body, so the soul must be eternal. It is not located in any part of the body, but is all-pervading, i.e. exists at the same time in all places (_vibhu_), and does not travel with the body but exists everywhere at the same time. But though atman is thus disconnected from the body, yet its actions are seen in the body because it is with the help of the collocation of bodily limbs, etc. that action in the self can be manifested or produced. It is unconscious in itself and acquires consciousness as a result of suitable collocations [Footnote ref 528].
Even at birth children show signs of pleasure by their different facial features, and this could not be due to anything else than the memory of the past experiences in past lives of pleasures and pains. Moreover the inequalities in the distribution of pleasures and pains and of successes and failures prove that these must be due to the different kinds of good and bad action that men performed in their past lives. Since the inequality of the world must have some reasons behind it, it is better to admit karma as the determining factor than to leave it to irresponsible chance.