Nyaya is one of the six philosophical schools of thought that defended itself with intellectual fervor. They are together called as upangas of Veda. These six system of thought were in existence for a period much before it was codified. It was very much part of vedic lore from time immemorial. Dr Radhakrishanan was of the opinion that the six conservative school were compelled codify their view and set forth logical defense of them because of the onslaught of skepticism prevalent in Buddhism. The various schools of thought have depended more on logic and philosophical character were not compromised while arriving at predictions or speculations.

Nyaya represent the analytic type of philosophy, and upheld the existence of material world that one can perceive and experience. Gautama authored the sutra for Nyaya; he systematized the principle of reasoning and distinguished the true from the false and gave an elaborate account of the various forms of sophisms and argumentative tricks. Nyaya accept only four means to gain Knowledge; namely,: Pratyakṣa (perception), Anumaṇa (inference), Upamaṇa (analogy) and Sabda (word by reliable sources). Nyaya emphasizes sixteen types of padarthas (entities) involved in cognizing.

These sixteen categories are pramana (valid means of knowledge), prameya (objects of valid knowledge), samsaya (doubt), prayojana (purpose), drishanta (example), siddhanta (conclusion), avayava (members of syllogism), tarka (argumentation), nirnaya (ascertainment), vada (debate), jalpa (disputation), vitanda (distructive criticism), hetvabhasa (fallacy), chala (quibbling), jati (sophisticated refutation) and nigrahasthana (point of defeat).

Nyaya and Vaiseshika systems were closely associated together and believed that Iswara created the world with the ultimate particle called anu. Here Iswara is the nimitta karana and anu are the upadana karana. Analogy is, to shape the clay into a pot a potter is needed. Without him there is no earthern pot, or in other words the pot without potter is non-existent. The arguments of Nyaya system were so powerful with academic fervor that they easily defeated Buddhist scholars in debates. Udyanacarya’s Baudhdhadhikaram give ample evidence in this respect.