Ньяя: Үнді философиясының мектебі

One of six schools of Hindu philosophy

Nyāya (Sanskrit:न्यायः, 'nyāya), literally meaning "justice", "rules", "method" or "judgment", is one of the six orthodox (Āstika) schools of Hindu philosophy that affirm the Vedas. Nyāya school's 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. 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. Naiyyayika scholars approached philosophy as a form of direct realism, stating that anything that really exists is in principle humanly knowable. To them, correct knowledge and understanding is different from simple, reflexive cognition; it requires Anuvyavasaya (अनुव्यवसाय, cross examination of cognition, reflective cognition of what one thinks one knows). Nyāya school shares some of its methodology and human suffering foundations with Buddhism; however, a key difference between the two is that Buddhism believes that there is neither a soul nor self; Nyāya school like some other schools of Hinduism such as Dvaita and Viśiṣṭādvaita believes that there is a soul and self, with liberation (mokṣa) as a state of removal of ignorance, wrong knowledge, the gain of correct knowledge, and unimpeded continuation of self.

Nyaya (न्याय) is a Sanskrit word which means justice, equality for all being, specially a collection of general or universal rules. In philosophical context, Nyaya encompasses propriety, logic and method. Panini, revered Sanskrit grammarian, derives the "Nyaya" from the root "i" which conveys the same meaning as "gam" – to go. "Nyaya" signifying logic is there etymologically identical with "nigama" the conclusion of a syllogism. Nyaya is related to several other concepts and words used in Indian philosophies: Hetu vidya (science of causes), Anviksiki (science of inquiry, systematic philosophy), Pramana sastra (epistemology, science of correct knowledge), Tattva sastra (science of categories), Tarka vidya (science of reasoning, innovation, synthesis), Vadartha (science of discussion) and Phakkika sastra (science of uncovering sophism, fraud, error, finding fakes). Some of these subsume or deploy the tools of Nyaya.

The Nyaya of logic is said to have been founded by a sage named Gautama. He is also known as Gautama, Aksapada and Dirghatapas. The names Gotama and Gautama points to the family to which he belonged while the names Aksapada and Dirghatapas refer respectively to his meditative habit and practice of long penance. By the 2nd century CE, Aksapada Gautama had composed Nyāya Sūtras, a foundational text for Nyāya school, that primarily discusses logic, methodology and epistemology. The most important contribution made by the Nyāya school to Hindu thought has been its treatises on epistemology and system of logic that, subsequently, has been adopted by the majority of the other Indian schools.

[[File:4 Pramanas, epistemology according to ancient Nyayasutras. svg|thumb|The Nyaya school considers perception, inference, comparison/analogy, and testimony from reliable sources as four means to correct knowledge, holding that perception is the ultimate source of such knowledge. The focus of Pramana is how correct knowledge can be acquired, how one knows, how one doesn't, and to what extent knowledge pertinent about someone or something can be acquired. The Naiyayikas (the Nyāya scholars) accepted four valid means (pramaṇa) of obtaining valid knowledge (pramana) – perception (pratyakṣa), inference (anumāna), comparison (upamāna) and word/testimony of reliable sources (śabda). The Nyāya scholars, along with those from other schools of Hinduism, also developed a theory of error, to methodically establish means to identify errors and the process by which errors are made in human pursuit of knowledge. These include Saṁśaya (समस्या, problems, inconsistencies, doubts) and Viparyaya (विपर्यय, contrariness, errors) which can be corrected or resolved by a systematic process of Tarka (तर्क, reasoning, technique).

The Naiyyayika maintains two modes or stages in perception. The first is called nirvikalpa (indeterminate), when one just perceives an object without being able to know its features, and the second savikalpa (determinate), when one is able to clearly know an object. All laukika and alaukika pratyakshas are savikalpa, but it is necessarily preceded by an earlier stage when it is indeterminate. Vātsāyana says that if an object is perceived with its name we have determinate perception but if it is perceived without a name, we have indeterminate perception. Jayanta Bhatta says that indeterminate perception apprehends substance, qualities and actions and universals as separate and indistinct, without any association with any names, whereas determinate perception apprehends them all together with a name. There is yet another stage called Pratyabhijñā, when one is able to re recognise something on the basis of memory.

Upamāna (उपमान) means comparison and analogy. The subject of comparison is formally called upameyam, the object of comparison is called upamānam, while the attribute(s) are identified as sāmānya. Thus, explains Monier Williams, if a boy says "her face is like the moon in charmingness", "her face" is upameyam, the moon is upamānam, and charmingness is sāmānya. The 7th century text Bhaṭṭikāvya in verses 10.28 through 10.63 discusses many types of comparisons and analogies, identifying when this epistemic method is more useful and reliable, and when it is not. Hiriyanna explains Sabda pramana as a concept which means testimony of a reliable and trustworthy person (āptavākya). The schools of Hinduism which consider it epistemically valid suggest that a human being needs to know numerous facts, and with the limited time and energy available, he can learn only a fraction of those facts and truths directly. He must rely on others, his parent, family, friends, teachers, ancestors and kindred members of society to rapidly acquire and share knowledge and thereby enrich each other's lives. This means of gaining proper knowledge is either spoken or written, but through Sabda (words). Testimony can be of two types, Vaidika (Vedic), which are the words of the four sacred Vedas, and Laukika, or words and writings of trustworthy human beings. Vaidika testimony is preferred over Laukika testimony. Laukika sourced knowledge must be questioned and revised as more trustworthy knowledge becomes available.

In Nyaya philosophy, direct realism asserts that our cognitions are informational states revealing external objects. According to Nyaya, the world consists of stable, three dimensional objects, and their system of categories accurately mirrors reality's structure. Nyaya philosophy emphasizes the importance of universals, qualities, and relations in understanding the organization of the world. These foundational elements are believed to play essential roles in determining the phenomenological, causal, and logical organization of the world, playing a crucial role in the classification of objects.

The Nyāya theory of error is similar to that of Kumarila's Viparita khyati (see Mimamsa). The Naiyyayikas also believe, like Kumarila, that error is due to a wrong synthesis of the presented and represented objects. The represented object is confused with the presented one. The word 'anyatha' means 'elsewise' and 'elsewhere' and both of these meanings are brought out in error. The presented object is perceived elsewise and the represented object exists elsewhere. They further maintain that knowledge is not intrinsically valid but becomes so due to extraneous conditions (paratah pramana during both validity and invalidity).

Early Naiyyayikas wrote very little about Ishvara (literally, the Supreme Soul). Evidence available so far suggests that early Nyāya scholars were non theistic or atheists. Later, and over time, Nyāya scholars tried to apply some of their epistemological insights and methodology to the question: does God exist? Some offered arguments against and some in favor. A literal interpretation of the three verses suggests that Nyāya school rejected the need for a God for the efficacy of human activity. Since human action and results do not require assumption or need of the existence of God, sutra IV.1.21 is seen as a criticism of the "existence of God and theism postulate". Kāryāt (lit. "from effect"): The world is an effect, all effects have efficient cause, hence the world must have an efficient cause. That efficient cause is God. The opening aphorism of the Nyāya Sūtra states that only the true knowledge leads to niḥśreyasa (liberation). Jayanta, in his Nyayamanjari describes salvation as a passive stage of the self in its natural purity, unassociated with pleasure, pain, knowledge and willingness.