  One of the philosophic problems that Nāgārjuna raised for epistemology has to do with an alleged regress of justification on the assumption that a pramāṇa is required in order to know and that to identify the source of a bit of knowledge is to certify the proposition embedded. Nāgārjuna claims that this is absurd in that it would require an infinite series of pramāṇa, of identification of a more fundamental pramāṇa for every pramāṇa relied on.