 The naturalism of the Naiyāyikas can be thrown into relief by their dispute with Mādhyamika Buddhists. The Mādhyamikas play the role of sceptic against the metaphysical realism of Nyāya. Nāgārjuna points out that a Naiyāyika cannot establish the pramāṇa-hood of a pramāṇa by means of another pramāṇa for that will lead to an infinite regress. Nor can the Naiyāyika establish it by pointing out its reliable character because that will lead to circularity (a piece of cognition is said to be pramā when it is produced by a reliable pramāṇa; to establish the reliability of a pramāṇa by referring to the fact that it has always been sufficient for generating a pramā is obviously circular). This objection would have been irrefutable if the Naiyāyikas had only one kind of pramā and one kind of pramāṇa in their epistemic repertoire. But as the Naiyāyikas admit four different pramāṇas for four different types of pramā, they can always fall back on other pramāṇas when the reliability of one is questioned: to justify perception, one might take recourse to inference, and again to justify inference one can rely on verbal cognition. As to establishing the reliability of the verbal cognition, they appeal to inference. As Quine once said, ‘Such scruples against circularity have little points once we have stopped dreaming of deducing sciences from observation. If we are simply to understand the link between observation and science, we are well advised to use any available information, including that provided by the very science whose link with observation we are seeking to understand.’ A naturalist need not be afraid of circularity.