Upamāna

Upamāna (उपमान) is the pramāṇa of comparison or analogy — knowledge that arises through the recognition of similarity between two things. It is the third of the four pramāṇas accepted by the Nyāya system and fills a gap that perception, inference, and testimony cannot cover: the knowledge that a previously unknown thing resembles a known one. For instance, a person who has never seen a gavaya (wild ox) but has heard it described as “like a cow” gains new knowledge upon seeing the wild animal.

The Nyāya tradition defines upamāna as arising from three conditions: awareness of a known object (upameya), awareness of its likeness to a familiar object (upamāna), and a declaration of similarity (sādharmya-vacana). Vātsyāyana’s Bhāṣya elaborates that this pramāṇa is particularly relevant for knowledge of unfamiliar objects through their resemblance to familiar ones. Udayana, in the Kusumāñjali, employs analogical reasoning in his arguments for the existence of God, demonstrating the practical application of upamāna in philosophical debate.

While the Nyāya tradition treats upamāna as an independent pramāṇa, the Buddhist and Cārvāka schools reject it, subsuming its functions under inference or perception. Buddhist logicians, who accept only perception and inference, argue that analogical reasoning is simply a variant of inferential reasoning based on perceived similarity. (The Mīmāṃsā and Advaita Vedānta schools accept upamāna, along with all six classical pramāṇas.) This disagreement reflects deeper methodological differences about whether analogy constitutes a genuinely distinct mode of knowing or merely a heuristic for constructing inferences.

Verification notes

• The Nyāya Sūtra reference to upamāna is in the standard critical edition.
• Vātsyāyana’s commentary provides the most detailed classical treatment of this pramāṇa.
• Udayana’s use of analogy in the Kusumāñjali is well-documented in Rajendra Mitra’s edition.
• Per the Wikipedia Pramana ref, the Mīmāṃsā/Advaita schools accept all six pramāṇas including upamāna, while Buddhism accepts only two; the “fourth pramāṇa” count and the Mīmāṃsā-rejection claim were corrected, and the classic gavaya/cow example restored.
• Audited against Wikipedia (September 2026).