It is an attempt to justify inference as a source of valid knowledge by way of pointing out the means of ascertaining Vyapti (Vyapatigraha) from the Navya Nyaya standpoint. The Carvakas believe that the inference can not be taken as a source of valid knowledge because the knowledge of Vyapti which is the special cause (Karapa) of inference cannot be known by any means and hence prediction about future is not justifiable. Here an effort has been made to refute the view of the Carvilas and rehabilitate Anumina as a source of Prama following the line of Gangesa and other Navya Naiya"yikas. By way of substantiating the Navya Nyaya view the views of the Buddhists, Jainas, Advaita Vedantins and other systems of Indian Philosophy (who admit Anumina as a source of Prama) have been put forward and carefully refuted. In the connection the role of Tarka in removing the doubt of Vyaptigraha (ascertainment of Vygpti) has been discussed in order to justify inference. The conclusive part of the book deals with some critical and evaluative remarks on the view of the Navya Naiyayakas.