Nyāya (Sanskrit: न्याय, nyā-yá), literally means "rules", "method" or "judgment". It is also the name of one of the six orthodox (astika) schools of Hinduism. This school's most significant contributions to Indian philosophy was systematic development of the theory of logic, methodology, and its treatises on epistemology.
Nyaya school's epistemology accepts four out of six Pramanas as reliable means of gaining knowledge – Pratyakṣa (perception), Anumāṇa (inference), Upamāṇa (comparison and analogy) and Śabda (word, testimony of past or present reliable experts). In its metaphysics, Nyaya school is closer to 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 Nyaya 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). An influential collection of texts on logic and reason is the Nyayasutras, attributed to Aksapada Gautama, variously estimated to have been composed between 6th-century BCE and 2nd-century CE.
Nyaya 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; Nyaya school like other schools of Hinduism believes that there is a soul and self, with liberation (moksha) 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 method, rule, specially a collection of general or universal rules. In some contexts, it means model, axiom, plan, legal proceeding, judicial sentence, or judgment. In the theory of logic, and Indian texts discussing it, the term also refers to an argument consisting of an enthymeme or sometimes for any syllogism. In philosophical context, Nyaya encompasses propriety, logic and method.
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 historical development of Nyaya school is unclear, although Nasadiya hymns of Book 10 Chapter 129 of Rigveda recite its spiritual questions in logical propositions. In early centuries BCE, states Clooney, the early Nyaya scholars began compiling the science of rational, coherent inquiry and pursuit of knowledge. By 2nd century CE, Aksapada Gautama had composed Nyayasutras, a foundational text for Nyaya school, that primarily discusses logic, methodology and epistemology. The Nyaya scholars that followed refined it, expanded it, and applied it to spiritual questions. While the early Nyaya scholars published little to no analysis on whether supernatural power or God exists, they did apply their insights into reason and reliable means to knowledge to the questions of nature of existence, spirituality, happiness and moksha. Later Nyaya scholars, such as Udayana, examined various arguments on theism and attempted to prove existence of God. Other Nyaya scholars offered arguments to disprove the existence of God.
The most important contribution made by the Nyaya 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.
The Nyaya metaphysics recognizes sixteen padarthas or categories and includes all six (or seven) categories of the Vaisheshika in the second one of them, called prameya. These sixteen categories are pramāṇa (valid means of knowledge), prameya (objects of valid knowledge), saṁśaya (doubt), prayojana (aim), dṛṣṭānta (example), siddhānta (conclusion), avayava (members of syllogism), tarka (hypothetical reasoning), nirṇaya (settlement), vāda (discussion), jalpa (wrangling), vitaṇḍā (cavilling), hetvābhāsa (fallacy), chala (quibbling), jāti (sophisticated refutation) and nigrahasthāna (point of defeat).
The Nyaya school of Hinduism developed and refined many treatises on epistemology that widely influenced other schools of Hinduism. Nyaya treated it as theory of knowledge, and its scholars developed it as Pramana-sastras. Pramana, a Sanskrit word, literally is "means of knowledge". It encompasses one or more reliable and valid means by which human beings gain accurate, true 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 Nyaya 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 Nyaya 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).
Pratyakṣa (perception) occupies the foremost position in the Nyaya epistemology. Perception can be of two types, laukika (ordinary) and alaukika (extraordinary). Ordinary perception is defined by Akṣapāda Gautama in his Nyaya Sutra (I,i.4) as a 'non-erroneous cognition which is produced by the intercourse of sense-organs with the objects'.
Indian texts identify four requirements for correct perception: Indriyarthasannikarsa (direct experience by one's sensory organ(s) with the object, whatever is being studied), Avyapadesya (non-verbal; correct perception is not through hearsay, according to ancient Indian scholars, where one's sensory organ relies on accepting or rejecting someone else's perception), Avyabhicara (does not wander; correct perception does not change, nor is it the result of deception because one's sensory organ or means of observation is drifting, defective, suspect) and Vyavasayatmaka (definite; correct perception excludes judgments of doubt, either because of one's failure to observe all the details, or because one is mixing inference with observation and observing what one wants to observe, or not observing what one does not want to observe).
Ordinary perception to Nyaya scholars was based on direct experience of reality by eyes, ears, nose, touch and taste. Extraordinary perception included yogaja or pratibha (intuition), samanyalaksanapratyaksa (a form of induction from perceived specifics to a universal), and jnanalaksanapratyaksa (a form of perception of prior processes and previous states of a 'topic of study' by observing its current state).
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 something and also it does not have any association with name, while determinate perception aprrehends all these together with a name. There is yet another stage called Pratyabhijñā, when one is able to re-recognise something on the basis of memory.
Anumāna (inference) is one of the most important contributions of the Nyaya. It can be of two types: inference for oneself (Svarthanumana, where one does not need any formal procedure, and at the most the last three of their 5 steps), and inference for others (Parathanumana, which requires a systematic methodology of 5 steps). Inference can also be classified into 3 types: Purvavat (inferring an unperceived effect from a perceived cause), Sheshavat (inferring an unperceived cause from a perceived effect) and Samanyatodrishta (when inference is not based on causation but on uniformity of co-existence). A detailed analysis of error is also given, explaining when anumana could be false.
The methodology of inference involves a combination of induction and deduction by moving from particular to particular via generality. It has five steps, as in the example shown:
In Nyāya terminology for this example, the hill would be called as paksha (minor term), the fire is called as sādhya (major term), the smoke is called as hetu, and the relationship between the smoke and the fire is called as vyapti (middle term). Hetu further has five characteristics: (1) It must be present in the Paksha, (2) It must be present in all positive instances, (3) It must be absent in all negative instances, (4) It must not incompatible with the minor term or Paksha and (5) All other contradictions by other means of knowledge should be absent. The fallacies in Anumana (hetvābhasa) may occur due to the following:
Upamāna (उपमान) means comparison and analogy. Upamana, states Lochtefeld, may be explained with the example of a traveller who has never visited lands or islands with endemic population of wildlife. He or she is told, by someone who has been there, that in those lands you see an animal that sort of looks like a cow, grazes like cow but is different from a cow in such and such way. Such use of analogy and comparison is, state the Indian epistemologists, a valid means of conditional knowledge, as it helps the traveller identify the new animal later. 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. In various ancient and medieval texts of Hinduism, 32 types of Upamāna and their value in epistemology are debated.
Śabda (शब्द) means relying on word, testimony of past or present reliable experts. 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). The reliability of the source is important, and legitimate knowledge can only come from the Sabda of reliable sources. The disagreement between the schools of Hinduism has been on how to establish reliability. Some schools, such as Carvaka, state that this is never possible, and therefore Sabda is not a proper pramana. Other schools debate means to establish reliability.
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.
Each school of Hinduism has its own treatises on epistemology, with different number of Pramanas. For example, compared to Nyaya school's four pramanas, Carvaka school has just one (perception), while Advaita Vedanta school recognizes six means to reliable knowledge.
A cause is defined as an unconditional and invariable antecedent of an effect and an effect as an unconditional and invariable consequent of a cause. The same cause produces the same effect; and the same effect is produced by the same cause. The cause is not present in any hidden form whatsoever in its effect.
The following conditions should be met:
Nyaya recognizes five kinds of accidental antecedents [Anyathasiddha]
Nyaya recognizes three kinds of cause:
The Nyaya 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 the represented objects. The represented object is confused with the presented one. The word 'anyatha' means 'elsewise' and 'elsewhere' and both 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 on account of 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 Nyaya scholars were non-theistic or atheists. Later, and over time, Nyaya 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.
In Nyayasutra's Book 4, Chapter 1, verses 19-21, postulates God exists, states a consequence, then presents contrary evidence, and from contradiction concludes that the postulate must be invalid.
The Lord is the cause, since we see that human action lacks results.
This is not so since, as a matter of fact, no result is accomplished without human action.
Since this is efficacious, the reason lacks force.— Nyaya Sutra, IV.1.19 - IV.1.21 
A literal interpretation of the three verses suggests that Nyaya 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". The context of the above verses includes various efficient causes. Nyayasutra verses IV.1.22 to IV.1.24, for example, examine the hypothesis that "random chance" explains the world, after these Indian scholars had rejected God as the efficient cause.
The Naiyyayikas believe that the bondage of the world is due to false knowledge, which can be removed by constantly thinking of its opposite (pratipakshabhavana), namely, the true knowledge. So the opening aphorism of the Nyāya Sūtra states that only the true knowledge lead to niḥśreyasa (liberation). But the Nyaya school also maintains that the God's grace is essential for obtaining true knowledge. Jayanta, in his Nyayamanjari describes salvation as a passive stage of self in its natural purity, unassociated with pleasure, pain, knowledge and willingness.
The earliest text of the Nyāya School is the Nyāya Sūtra of Akṣapāda Gautama. The text is divided into five books, each having two sections. Vātsāyana's Nyāya Bhāṣya is a classic commentary on the Nyāya Sūtra. Udyotakara's Nyāya Vārttika (6th century CE) is written to defend Vātsāyana against the attacks made by Dignāga. Vācaspati Miśra's Nyāyavārttikatātparyaṭīkā (9th century CE) is the next major exposition of this school. Two other texts, Nyāyaṣūcinibandha and Nyāyasūtraddhāra are also attributed to him. Udayana's (984 CE) Nyāyatātparyapariśuddhi is an important commentary on Vācaspati's treatise. His Nyāyakusumāñjali is the first systematic account of theistic Nyāya. His other works include Ātmatattvaviveka, Kiraṇāvali and Nyāyapariśiṣṭa. Jayanta Bhatta's Nyāyamañjari (10th century CE) is basically an independent work. Bhāsavarajña's Nyāyasāra (10th century CE) is a survey of Nyāya philosophy.
The later works on Nyāya accepted the Vaiśeṣika categories and Varadarāja's Tārkikarakṣā (12th century CE) is a notable treatise of this syncretist school. Keśava Miśra's Tārkabhaṣā (13th century CE) is another important work of this school.
Gangeśa Upādhyāya's Tattvacintāmaṇi (12th century CE) is the first major treatise of the new school of Navya-Nyāya. His son, Vardhamāna Upādhyāya's Nyāyanibandhaprakāśa (1225 CE), though a commentary on Udayana's Nyāyatātparyapariśuddhi, incorporated his father's views. Jayadeva wrote a commentary on Tattvacintāmaṇi known as Āloka (13th century CE). Vāsudeva Sārvabhauma's Tattvacintāmaṇivyākhyā (16th century CE) is first great work of Navadvipa school of Navya-Nyāya. Raghunātha Śiromaṇi's Tattvacintāmaṇidīdhiti and Padārthakhaṇḍana are the next important works of this school. Viśvanatha's Nyāyasūtravṛtti (17th century CE) is also a notable work. The Commentaries on Tattvacintāmaṇidīdhiti by Jagadish Tarkalankar (17th century CE) and Gadadhar Bhattacharya (17th century CE) are the last two notable works of this school.
Annaṁbhatta (17th century CE) tried to develop a consistent system by combining the ancient and the new schools, Prācina nyāya and Navya-Nyāya and Vaiśeṣika to develop the nyāya-vaiśeṣika school. His Tarkasaṁgraha and Dīpikā are the popular manuals of this school.
"It is significant that the name logic is etymologically connected with the Greek god logos, which denotes both 'thought' and 'word' or 'discourse'. The significance of this etymological connection can be adequately appreciated if it is remembered that logic, in its rise and development in the western world, particularly in Greece, was closely connected with rhetoric. Thus the name logic is of a tell-tale character in its application to logic in the West ; and it may be taken to indicate how, almost from its very rise, western logic found, itself in the firm grip of formalism and how it took more than twenty centuries for the scientific method underlying Aristotle's Organon to be redeemed, brought into prominence and implemented in the Novum Organum of Francis Bacon (1561-1626). The term logic should not be taken to carry with it all these implications of European history when it is used in the phrase Indian logic."
The essential features of logic in the Western tradition are well captured in the following statement by a famous logician Alonzo Church :
"Logic is the systematic study of the structure of propositions and of the general conditions of valid inference by a method, which abstracts from the content or matter of the propositions and deals only with their logical form. This distinction between form and matter is made whenever we distinguish between the logical soundness or validity of a piece of reasoning and the truth of the premises from which it proceeds and in this sense is familiar from everyday usage. However, a precise statement of the distinction must be made with reference to a particular language or system of notation, a formalised language, which shall avoid the inexactness and systematically misleading irregularities of structure and expression that are found in ordinary (colloquial or literary) English and other natural languages and shall follow or reproduce the logical form. "
Thus, the basic features of Western logic are: It deals with a study of ‘propositions’, specially their ‘logical form’ as abstracted from their ‘content’ or ‘matter’. It deals with ‘general conditions of valid inference’, wherein the truth or otherwise of the premises have no bearing on the ‘logical soundness or validity’ of an inference. It achieves this by taking recourse to a symbolic language that has little to do with natural languages. The main concern of Western logic, in its entire course of development, has been one of systematising patterns of mathematical reasoning, with the mathematical objects being thought of as existing either in an independent ideal world or in a formal domain. Indian logic however, does not deal with ideal entities, such as propositions, logical truth as distinguished from material truth, or with purely symbolic languages that apparently have nothing to do with natural languages.
The central concern of Indian logic as founded in Nyāya is epistemology, or the theory of knowledge. Thus Indian logic is not concerned merely with making arguments in formal mathematics rigorous and precise, but attends to the much larger issue of providing rigour to the arguments encountered in natural sciences (including mathematics, which in Indian tradition has the attributes of a natural science and not that of a collection of context free formal statements), and in philosophical discourse. Inference in Indian logic is ‘deductive and inductive’, ‘formal as well as material’. In essence, it is the method of scientific enquiry. Indian ‘formal logic’ is thus not ‘formal’, in the sense generally understood: in Indian logic ‘form’ cannot be entirely separated from ‘content’. In fact, great care is exercised to exclude from logical discourse terms, which have no referential content. No statement, which is known to be false, is admitted as a premise in a valid argument. Thus, the ‘method of indirect proof’ (reductio ad absurdum) is not accepted as a valid method−neither in Indian philosophy nor in Indian mathematics−for proving the existence of an entity whose existence is not demonstrable (even in principle) by other (direct) means of proof.
Indian logic does not make any attempt to develop a purely symbolic and content independent or ‘formal language’ as the vehicle of logical analysis. Instead, what Indian logic, especially in its later phase of Navya-Nyāya starting with the work of Gāngeśa Upādhyāya of 14th century, has developed is a technical language, which is based on the natural language Sanskrit, yet avoids ‘inexactness’ and ‘misleading irregularities’ by various technical devices. This technical language, being based on the natural language Sanskrit, inherits a certain natural structure and interpretation, and sensitivity to the context of enquiry. On the other hand, the symbolic formal systems of Western logic, though considerably influenced in their structure (say, in quantification, etc.) by the basic patterns discernible in European languages, are professedly purely symbolic, carrying no interpretation whatsoever−such interpretations are supposed to be supplied separately in the specific context of the particular field of enquiry ‘employing’ the symbolic formal system.
Buddhist logico-epistemology is a term used in Western scholarship for pramāṇa-vāda (doctrine of proof) and Hetu-vidya (science of causes). Pramāṇa-vāda is an epistemological study of the nature of knowledge; Hetu-vidya is a system of logic. These models developed in India during the 5th through 7th centuries.
The early Buddhist texts show that the historical Buddha was familiar with certain rules of reasoning used for debating purposes and made use of these against his opponents. He also seems to have held certain ideas about epistemology and reasoning, though he did not put forth a logico-epistemological system. The structure of debating rules and processes can be seen in the early Theravada text the Kathāvatthu.
The first Buddhist thinker to discuss logical and epistemic issues systematically was Vasubandhu in his Vāda-vidhi ("A Method for Argumentation"), who was influenced by the Hindu work on reasoning, the Nyāya-sūtra.A mature system of Buddhist logic and epistemology was founded by the Buddhist scholar Dignāga (c. 480–540 CE) in his magnum opus, the Pramāṇa-samuccaya. Dharmakirti further developed this system with several innovations. Dharmakirti's Pramanavarttika ('Commentary on Valid Cognition') became the main source of epistemology and reasoning in Tibetan Buddhism.Gangesha Upadhyaya
Gangesha Upadhyaya (Sanskrit: गंगेश उपाध्याय, Gaṅgeśa Upādhyāya) (late 12th century) was an Indian mathematician and philosopher from the kingdom of Mithila. He established the Navya-Nyāya ("New Logic") school. His Tattvacintāmaṇi (The Jewel of Thought on the Nature of Things), also known as Pramāṇacintāmaṇi (The Jewel of Thought on the Means of Valid Knowledge), is the basic text for all later developments. The logicians of this school were primarily interested in defining their terms and concepts related to non-binary logical categories.Guṇa
Guṇa depending on the context means "string, thread, or strand", or "virtue, merit, excellence", or "quality, peculiarity, attribute, property".The concept is originally notable as a feature of Samkhya philosophy, though possibly a later feature of it. The gunas are now a key concept in nearly all schools of Hindu philosophy. There are three gunas, according to this worldview, that have always been and continue to be present in all things and beings in the world. These three gunas are called: sattva (goodness, constructive, harmonious), rajas (passion, active, confused), and tamas (darkness, destructive, chaotic). All of these three gunas are present in everyone and everything, it is the proportion that is different, according to Hindu worldview. The interplay of these gunas defines the character of someone or something, of nature and determines the progress of life.In some contexts, it may mean "a subdivision, species, kind, quality", or an operational principle or tendency of something or someone. In human behavior studies, Guna means personality, innate nature and psychological attributes of an individual.Like all Sanskrit technical terms, guṇa can be difficult to summarize in a single word. Its original and common meaning is a thread, implying the original materials that weave together to make up reality. The usual, but approximate translation in common usage is "quality".Hindu philosophy
Hindu philosophy refers to a group of darśanas (philosophies, world views, teachings) that emerged in ancient India. These include six systems (ṣaḍdarśana) – Sankhya, Yoga, Nyaya, Vaisheshika, Mimamsa and Vedanta. These are also called the Astika (orthodox) philosophical traditions and are those that accept the Vedas as an authoritative, important source of knowledge. Ancient and medieval India was also the source of philosophies that share philosophical concepts but rejected the Vedas, and these have been called nāstika (heterodox or non-orthodox) Indian philosophies. Nāstika Indian philosophies include Buddhism, Jainism, Cārvāka, Ājīvika, and others.Scholars have debated the relationship and differences within āstika philosophies and with nāstika philosophies, starting with the writings of Indologists and Orientalists of the 18th and 19th centuries, which were themselves derived from limited availability of Indian literature and medieval doxographies. The various sibling traditions included in Hindu philosophies are diverse, and they are united by shared history and concepts, same textual resources, similar ontological and soteriological focus, and cosmology. While Buddhism and Jainism are considered distinct philosophies and religions, some heterodox traditions such as Cārvāka are often considered as distinct schools within Hindu philosophy.Hindu philosophy also includes several sub-schools of theistic philosophies that integrate ideas from two or more of the six orthodox philosophies, such as the realism of the Nyāya, the naturalism of the Vaiśeṣika, the dualism of the Sāṅkhya, the monism and knowledge of Self as essential to liberation of Advaita, the self-discipline of yoga and the asceticism and elements of theistic ideas. Examples of such schools include Pāśupata Śaiva, Śaiva siddhānta, Pratyabhijña, Raseśvara and Vaiṣṇava. Some sub-schools share Tantric ideas with those found in some Buddhist traditions. The ideas of these sub-schools are found in the Puranas and Āgamas.Each school of Hindu philosophy has extensive epistemological literature called pramāṇaśāstras, as well as theories on metaphysics, axiology, and other topics.Indian logic
The development of Indian logic dates back to the anviksiki of Medhatithi Gautama (c. 6th century BCE); the Sanskrit grammar rules of Pāṇini (c. 5th century BCE); the Vaisheshika school's analysis of atomism (c. 6th century BCE to 2nd century BCE); the analysis of inference by Gotama (c. 6th century BC to 2nd century CE), founder of the Nyaya school of Hindu philosophy; and the tetralemma of Nagarjuna (c. 2nd century CE).
Indian logic stands as one of the three original traditions of logic, alongside the Greek and the Chinese logic. The Indian tradition continued to develop through early to modern times, in the form of the Navya-Nyāya school of logic.Jayanta Bhatta
Jayanta Bhatta (c. 9th Century CE) was a Kashmir poet and a philosopher of Nyaya school of Hindu philosophy. In his philosophical treatise Nyayamanjari and drama Agamadambara, Jayanta mentions the king Shankaravarman (883 – 902 CE) as his contemporary. Also, his son Abhinanda in his Kadambari-kathasara, mentioned that the great grandfather of Jayanta was a minister of King Lalitaditya of 8th century CE. So most probably Jayanta belonged to the last quarter of 9th Century CE.Navya-Nyāya
The Navya-Nyāya or Neo-Logical darśana (view, system, or school) of Indian logic and Indian philosophy was founded in the 13th century CE by the philosopher Gangeśa Upādhyāya of Mithila and continued by Raghunatha Siromani. It was a development of the classical Nyāya darśana. Other influences on Navya-Nyāya were the work of earlier philosophers Vācaspati Miśra (900–980 CE) and Udayana (late 10th century). It remained active in India through to the 18th century.
Gangeśa's book Tattvacintāmaṇi ("Thought-Jewel of Reality") was written partly in response to Śrīharśa's Khandanakhandakhādya, a defence of Advaita Vedānta, which had offered a set of thorough criticisms of Nyāya theories of thought and language. In his book, Gangeśa both addressed some of those criticisms and – more important – critically examined the Nyāya darśana itself. He held that, while Śrīharśa had failed to successfully challenge the Nyāya realist ontology, his and Gangeśa's own criticisms brought out a need to improve and refine the logical and linguistic tools of Nyāya thought, to make them more rigorous and precise.
Tattvacintāmani dealt with all the important aspects of Indian philosophy, logic, set theory, and especially epistemology, which Gangeśa examined rigorously, developing and improving the Nyāya scheme, and offering examples. The results, especially his analysis of cognition, were taken up and used by other darśanas.
Navya-Nyāya developed a sophisticated language and conceptual scheme that allowed it to raise, analyse, and solve problems in logic and epistemology. It systematised all the Nyāya concepts into four main categories (sense-)perception (pratyakşa), inference (anumāna), comparison or similarity (upamāna), and testimony (sound or word; śabda).Nyaya Tharasu
Nyaya Tharasu is a 1989 Indian Tamil language film, directed by K. Rajeshwar, making his directorial debut, starring Nizhalgal Ravi and Radha in lead roles. The film, produced by M. Veda had musical score by Sankar Ganesh and was released in 1989. The film was a remake of Malayalam film Panchagni. A remarkable tale of a remarkable woman, who puts her commitment to social activism above everything else, including her own love for an adoring man. Under the debut direction of K. Rajeshwar, Radha made a sensation in Tamil in one of the most powerful female characters in Indian cinema ever.Nyayakusumanjali
Nyayakusumanjali ( A Handful of Flowers of Logic) is a treatise in Sanskrit composed by 10th century CE Indian logician and philosopher Udayana. The work has been described as codification of the Hindu proof for the existence of God. It has been noted that this treatise is the most elaborate and the most fundamental work of the Nyaya-Vaiseshika school on the Isvara doctrine.Nyāya Sūtras
The Nyāya Sūtras is an ancient Indian Sanskrit text composed by Akṣapāda Gautama, and the foundational text of the Nyaya school of Hindu philosophy. The date when the text was composed, and the biography of its author is unknown, but variously estimated between 6th-century BCE and 2nd-century CE. The text may have been composed by more than one author, over a period of time. The text consists of five books, with two chapters in each book, with a cumulative total of 528 aphoristic sutras, about rules of reason, logic, epistemology and metaphysics.The Nyāya Sūtras is a Hindu text, notable for focusing on knowledge and logic, and making no mention of Vedic rituals. The first book is structured as a general introduction and table of contents of sixteen categories of knowledge. Book two is about pramana (epistemology), book three is about prameya or the objects of knowledge, and the text discusses the nature of knowledge in remaining books. It set the foundation for Nyaya tradition of the empirical theory of validity and truth, opposing uncritical appeals to intuition or scriptural authority.The Nyaya sutras cover a wide range of topics, including Tarka-Vidyā, the science of debate or Vāda-Vidyā, the science of discussion. The Nyāya Sutras are related to but extend the Vaiśeṣika epistemological and metaphysical system. Later commentaries expanded, expounded and discussed Nyaya sutras, the earlier surviving commentaries being by Vātsyāyana (c.450–500 CE), followed by the Nyāyavārttika of Uddyotakāra (c. 6th–7th centuries), Vācaspati Miśra's Tātparyatīkā (9th century), Udayana's Tātparyapariśuddhi (10th century), and Jayanta's Nyāyamañjarī (10th century).Padārtha
Padārtha is a Sanskrit word for "categories" in Vaisheshika and Nyaya schools of Hindu philosophy.Prashastapada
Praśastapāda (Sanskrit: प्रशस्तपाद) was an ancient Indian philosopher. He wrote the Padārtha-dharma-saṅgraha (Collection of Properties of Matter) and a commentary, titled Praśastapāda Bhāṣya , on the Vaisheshika Sutras of Kanada (Circa 6th Century BCE), both texts are comprehensive books in physics. In these texts Prashastapada discusses the properties of motion. Ganganath Jha had translated Praśastapāda Bhāṣya which translation was published in 1916. Prashasta or Praśasta (Sanskrit: प्रशस्त) means praised or praiseworthy, lauded or laudable, commended or commendable or eulogized.Dayananda Saraswati writes that the Sutras of Kanāda and Padārthadharmasaṅgraha of Praśastapāda do not show much influence of the Nyaya System. Praśastapāda Bhāṣya is actually not a commentary but an independent compendium of the tenets of the Vaisheshika School. Udayanacharya of the Navya-Nyāya School, the author of Lakṣaṇāvalī which gives the definitions of Vaiśeṣika terms, and Nyāya Kusumanjali which is a systematic account of Nyaya Theism, who also belonged to Mithila, had written Kiranavali which is a commentary on Praśastapāda Bhāṣya .Praśastapāda can be tentatively dated to the second half of the 6th century C.E. The Vaiśeṣika philosophy recognizes twenty-four gunas or qualities that are inherent in substances; these include seventeen gunas listed by Kanada and seven gunas – gurutva (heaviness), dravatva (fluidity), sneha (viscidity), dharma (merit), adharma (demerit), shabda (sound) and samskara (faculty) - added by Praśastapāda. Vyomavati of Vyomaśekhara, Nyayakandali of Shridhara, Kiranavali of Udayana and Lilavati of Śrīvatsa are well known commentaries on his works.Praśastapāda refers to a type of perception that is the simple intuition ( alochana ) of the proper form ( svarupa ) of an entity, which is the apprehension of an undifferentiated ( avibhktam ) whole arising from cognition of its specific universals. This is the preliminary stage. He differs from Dignāga for whom the determinates of cognitions are subjective constructs imposed upon the given, and constructive cognition is not a perception; Praśastapāda, who was a realist, avers that the determinates are objective constituents of reality and their conceptual co-relates are not inter-subjective fictions. Praśastapāda by redefining substance as per se a possessor of attributes opened new turf by separating the cosmological from the logical dimensions of concepts. His commentary overshadowed the Vaisheshika Sutras and became the main vehicle for later commentaries. Praśastapāda describes the dissolution of the earth, water, air and fire in terms of their atomic constituents but excludes space because space is non-atomic. With regard to the conjoining and disjoining of atoms he includes a higher will or order as the guiding principle of universal dissolution which over-rides the natural karma of atoms.Kaṇāda does not directly refer to Ishvara (God) but Praśastapāda sees Ishvara as the cause of the universe but does not explain how God creates.Raghunatha Siromani
Raghunatha Shiromani (Bengali: রঘুনাথ শিরোমণি, IAST: Raghunātha Śiromaṇi) (c. 1477–1547) was an Indian philosopher and logician. He was born at Nabadwip in present-day Nadia district of West Bengal state. He was the grandson of Śulapāṇi (c. 14th century CE), a noted writer on Smṛti from his mother's side. He was a pupil of Vāsudeva Sārvabhauma. He brought the new school of Nyaya, Navya Nyāya, representing the final development of Indian formal logic, to its zenith of analytic power.
Raghunatha's analysis of relations revealed the true nature of number, inseparable from the abstraction of natural phenomena, and his studies of metaphysics dealt with the negation or nonexistence of a complex reality. His most famous work in logic was the Tattvacintāmaṇidīdhiti, a commentary on the Tattvacintāmaṇi of Gangeśa Upādhyāya, founder of the Navya Nyāya school.
A descriptive information of Raghunatha with some controversial issues (his connection with Mahaprabhu Shri Chaitanya) and bibliography are to be found at
Raghunatha: A Name of Negatives. The contemporary deployment of a new category, svatva ( endowment, possessed-ness, entitlement, my-ness), introduced by Raghunatha, is discussed in Language: From I-dentity to My-dentityTarka-Sangraha
Tarka-Sangraha is a treatise in Sanskrit giving a foundational exposition of the ancient Indian system of logic and reasoning. The work is authored by Annambhatta and the author himself has given a detailed commentary, called Tarka-Sangraha Deepika, for the text. Annambhatta composed the text as well as the commentary in the second half of 17th century CE. The text of Tarka-sangraha is a small book with about 15 pages only and it was composed to help boys and girls learn easily the basic principles of Nyaya. Of all the works of Annambhatta, only Tarka-Sangraha and its commentary attained wide acceptance. They have been used as basic text for beginners for several generations.
In Indian philosophical writings, the traditional structure of presenting a system consisted of three things: uddesa (listing of items to be discussed), laksana (defining each item in the list) and pariksa (critically examining whether the definitions apply properly to the items defined). The Tarka-Sangraha follows this model except for the third item of pariksa. The text presents the ontology, logic and epistemology of the Nyaya-Vaiseshika system.Tattvacintāmaṇi
Tattvacintāmaṇi is a treatise in Sanskrit authored by 12th-century CE Indian logician and philosopher Gangesa Upadhyaya (also known as Gangesvara Upadhyaya). The title may be translated into English as "A Thought-jewel of Truth." The treatise is also known as Pramāṇa-cintāmaṇi ("A Thought-jewel of Valid Knowledge").The treatise introduced a new era in the history of Indian logic. Satis Chandra Vidyabhusana in his authoritative 681-page history of Indian logic divided the millennia long history of Indian logic into three sometimes overlapping periods: Ancient period (650 BCE – 100 CE), Medieval period (100 CE – 1200 CE) and Modern period (from 900 CE). He also identified certain standard work as typical representative of each of these periods. Tattvacinthamani of Gangesa is the text identified as the standard work of the Modern period in the history of Indian logic, the standard works for the earlier periods being Nyāya Sūtra by Akṣapāda Gautama (Ancient period) and Pramāṇa-samuccaya by Dignāga (Medieval period). The fact that Tattvacintāmaṇi was highly popular is attested by the appearance of a large number of commentaries that have been produced in the centuries that followed the appearance of the book. It has been estimated that while the original text of Tattvacintāmaṇi has about 300 pages, all the commentaries put together contain about a million pages.Udayana
Udayana, also known as Udayanācārya (Udyanacharya, or Master Udayana), was a very important Hindu logician of the tenth century who attempted to reconcile the views held by the two major schools of logic (Nyaya and Vaisheshika). This became the root of the Navya-Nyāya school of the thirteenth century, established by the Gangesha Upadhyaya ("New Nyāya") school of "right" reasoning, which is still recognized and followed in some regions of India. He lived in Kariyan village in Mithila, near present-day Darbhanga, Bihar state, India.
Udayana wrote a sub-gloss on Vachaspati's work called the Nyaya-vaartika-taatparya-tiikaa-parishuddhi. He wrote several other works such as the Kusumanjali, Atma-tattva-viveka, Kiranaavali and Nyaya-parishishhta (also called Bodha siddhi or Bodha shuddhi).
He is given credit by Naiyâyikas for having demolished in a final fashion the claims of the Buddhist logicians. All his works, or at least all of which we know, have been preserved, which attest to the respect in which he was held from the beginning.Vaisheshika
Vaisheshika or Vaiśeṣika (Sanskrit: वैशेषिक) is one of the six orthodox schools of Hindu philosophy (Vedic systems) from ancient India. In its early stages, the Vaiśeṣika was an independent philosophy with its own metaphysics, epistemology, logic, ethics, and soteriology. Over time, the Vaiśeṣika system became similar in its philosophical procedures, ethical conclusions and soteriology to the Nyāya school of Hinduism, but retained its difference in epistemology and metaphysics.
The epistemology of Vaiśeṣika school of Hinduism, like Buddhism, accepted only two reliable means to knowledge: perception and inference. Vaiśeṣika school and Buddhism both consider their respective scriptures as indisputable and valid means to knowledge, the difference being that the scriptures held to be a valid and reliable source by Vaiśeṣikas were the Vedas.
Vaisheshika school is known for its insights in naturalism. It is a form of atomism in natural philosophy. It postulated that all objects in the physical universe are reducible to paramāṇu (atoms), and one's experiences are derived from the interplay of substance (a function of atoms, their number and their spatial arrangements), quality, activity, commonness, particularity and inherence. Everything was composed of atoms, qualities emerged from aggregates of atoms, but the aggregation and nature of these atoms was predetermined by cosmic forces. Ajivika metaphysics included a theory of atoms which was later adapted in Vaiśeṣika school.According to Vaiśeṣika school, knowledge and liberation were achievable by a complete understanding of the world of experience..
Vaiśeṣika darshana was founded by Kaṇāda Kashyapa around the 6th to 2nd century BC.Vācaspati Miśra
Vachaspati Mishra was a 9th- or 10th-century CE Indian philosopher. He wrote so broadly that he was known as "one for whom all systems are his own", or in Sanskrit, a sarva-tantra-sva-tantra. Vācaspati Miśra was a prolific scholar and his writings are extensive, including bhasya (commentaries) on key texts of almost every 9th-century school of Hindu philosophy with notes on non-Hindu or nāstika traditions such as Buddhism and Carvaka. He also wrote one non-commentary, Tattvabindu, or Drop of Truth, which focuses on Mīmāṃsā theories of sentence meaning. Some of his works are lost to history or yet to be found.Little is known about Vācaspati Miśra's life, and the earliest text that has been dated with certainty is from 840 CE, and he was at least one generation younger than Adi Śaṅkara. However, an alternate date for the same text may be 976 CE, according to some scholars, a confusion that is based on whether Hindu Śaka or Vikrama era calendar is used for the dating purposes. His scholarship is revered in the Hindu tradition, which believes that he was a Maithil Brahmin from Andhra Tharhi
Ātman () is a Sanskrit word that means inner self or soul. In Hindu philosophy, especially in the Vedanta school of Hinduism, Ātman is the first principle, the true self of an individual beyond identification with phenomena, the essence of an individual. In order to attain liberation (moksha), a human being must acquire self-knowledge (atma jnana), which is to realize that one's true self (Ātman) is identical with the transcendent self Brahman.The six orthodox schools of Hinduism believe that there is Ātman (soul, self) in every being. This is a major point of difference with the Buddhist doctrine of Anatta which holds that there is no unchanging soul or self.