Pramāṇa (3): Upamāna or Comparison

According to Nyāya, the third source of valid knowledge or pramāṇa is upamāna. It can be stated as the source of knowledge of the relation between a name and the nameable object or between a word and its denotation.^[1] A person, who has never seen a gavaya (wild cow) and does not know the meaning of the word gavaya, learns from a forester that ‘a gavaya is like a cow’. This statement is technically known as atideśavākya. When this person sees a gavaya in the forest, he first observes the similarity of the creature with a cow and then remembers the statement of the forester that a gavaya is like a cow. Then he comes to have the final knowledge that this animal is what is denoted by the word gavaya. This is upamiti.^[2] Here the instrument (karaṇa) of upamiti is the knowledge of similarity and the remembrance of the statement of the forester serves as the operative cause (vyāpāra) for an upamiti.^[3] According to Nyāya, upamāna is a way of knowing the denotation of words and solving the problem of identification.^[4]

The Vaiśeṣika does not accept upamāna as an independent source of knowledge. Praśastapāda holds it to be a case of inference. The Mīmāṃsakas recognize it as a separate source of valid knowledge, but their account of it is different from Nyāya.