Nyāya (Sanskrit: न्यायः, IAST: nyāyaḥ), literally meaning "justice", "rules", "method" or "judgment", is one of the six orthodox (Āstika) schools of Hindu philosophy. Nyāya's most significant contributions to Indian philosophy were the systematic development of the theory of logic, methodology, and its treatises on epistemology.
Nyāya epistemology accepts four out of six pramanas as reliable means of gaining knowledge – pratyakṣa (perception), anumāṇa (inference), upamāna (comparison and analogy) and śabda (word, testimony of past or present reliable experts). In its metaphysics, Nyāya school is closer to the Vaisheshika school of Hinduism than others. It holds that human suffering results from mistakes/defects produced by activity under wrong knowledge (notions and ignorance). Moksha (liberation), it states, is gained through right knowledge. This premise led Nyāya to concern itself with epistemology, that is the reliable means to gain correct knowledge and to remove wrong notions. False knowledge is not merely ignorance to Naiyyayikas, it includes delusion. Correct knowledge is discovering and overcoming one's delusions, and understanding true nature of soul, self and reality.