 The Indian philosophical tradition distinguishes a variety of epistemic instruments (pramāṇa) by which epistemic objects (prameya) are accessed. Which epistemic instruments were accepted and how their function is understood differs amongst philosophical theories. In his discussion of epistemology Nāgārjuna lists four such instruments: perception (pratyakṣa), inference (anumāna), recognition of likeness (upamāna), and testimony (āgama). His primary concern is not a discussion of the nature and interrelation of these different epistemic instruments, but the question of how to establish any particular set of such instruments, whether it is the one just indicated or a different one. Once we have agreed that the existence of epistemic objects is established by the epistemic instruments (as for example the existence of the desk in front of me is established by my perceptual abilities, in this case primarily non-defective vision) we then have to address the further question of how to establish the instruments. How do we know that these instruments are good guides to the objects out there in the world?