Nyaya Sutra: A study of Epistemology

Reeshabh Choudhary
7 min readDec 13, 2022
Six Indian Philosophies, we will be discussing about Nyaya in this article.

Logic is designated in Sanskrit not only by word ‘Nyaya’ but also different other words which represent various aspects of this science of Logic. Hetu-Vidya refers as science of causes, Anvishiki as science of inquiry, Pramana-Shashtra as science of correct knowledge, Tattava-Shahstra as science of categories, Tarka-Vidya as science of reasoning, Vadartha as science of discussion and so on. The philosophy of Nyaya, also known as Nyaya-Sutra/Dharma-Sutra, is said to have been founded by Rishi Gautama Aksapada. Interesting to note here is that Gautama refers to the linage or family of Rishi Gautam from early Vedic Period and Aksapada is the name give to the sage and refers to the sage’s meditative habit and practice of long penance. Geographically, origin place of Sage Gautama is referred to Mithila, currently Darbhanga in North Bihar, India. His roots to this place have been cross referenced in scriptures such as Ramayana and Vayupurana. Historically, the year of Sage Gautama Aksapada, from the family of Rishi Gautam, is traced around 550 BC., yet the exact timing is always debatable.

The complete works of Nyaya Sutra is divided into five books, however, except the first two books, referred as ‘Ahnika’, rest of the material is a commentary on other philosophies such as Vaisesika, Yog, Mimansa, Vedanta, etc. marks the writing of various authors as add on. As per ancient Indian tradition, knowledge was initially transferred to pupils orally from their teachers, so it is not certain whether Rishi Gautama Aksapada himself wrote the first two chapters or his lectures were later on translated by his pupils or descendants. However, in all the works related to Nyaya Sutra, Rishi Aksapada is ascribed as the founder of the philosophy. Works on Rishi Vatsayana (450 A D.), author of Kamasutra, on Nyaya Sutra is one of the last and considerable addition to the treatise of Nyaya Sutra.

Nyaya is one of the six foundational philosophies of Indic thought school. In the early period of its foundation, the philosophy of logic was not well received by the section of Brahmans and due to its diversion from Vedic doctrines, it was not favored or even acknowledged by many contemporary sages in their works. Gradually, this system of philosophy came to attach due weightage to the authority of Vedas and as a reconciliation principle of Nyaya were assimilated in other systems of philosophies such as Vaisesika, Yog, Mimansa, Samkhya, etc. Indian epic Mahabharat is full of references to tenets of Nyaya Sutra on various occasions. Study of Nyaya sutra was one of the primal courses a king must had to go through since Vedic period in India.

Let us now delve into the core concepts of Nyaya Sutra.

In the very first sutra of first chapter of Book I of Nyaya-Sutra, it is defined that Supreme felicity is attained by knowledge about nature of sixteen categories, viz., ‘pramana’ — means of right knowledge, ‘prameya’ — object of right knowledge, ‘samasya’ — doubt, ‘paryojna’ — purpose, ‘drastanta’ — familiar instance, ‘siddhanta’ — established tenets, ‘avyaya’ — members, ‘tarka’ — confutation, ‘nirnaya’ — ascertainment, ‘vada’ — discussion, ‘jalpa’ — wrangling, ‘vitanda’ — cavil, ‘hetvabhasha’ — fallacy, ‘chala’- quibble, ‘jati’ — futility and ‘nigrahasthana’ — occasion for rebuke.

Epistemology, pramāṇa-śāstra, is concerned with the knowledge possessing which a person acts confidently. Genuine doubt or challenge bumps us up to the second level of reflective knowledge, that is, if we can state reasons or justification. This is often not easy to do since justification requires either argument or source identification. Ascribing to the Indian philosophy of birth and death cycle and ways to attain ’moksha’ — supreme fulfilment/release (soul getting release of this cycle); the Nyaya Sutra states that pain, birth, activity, faults and misapprehension in their uninterrupted course constitute the world and only right means of knowledge can set one to the path of release or ‘moksha’. Perception, inference, comparison, and word (referred as verbal testimony, not the literal meaning as an English word) are the means of right knowledge.

The Nyaya Sutra defines a soul to have characteristics such as desire, aversion, volition, pleasure, pain, and intelligence. It explicitly defines body as a site of gestures as it strives to achieve what is desirable and rejects what is rejectable, senses and sentiments. Nyaya Sutra discusses about perception of mind being in a single state at one point of time. Since, mind can be in conjunction with only one sense organ at a time, hence, perception can not exist in two forms within a mind. Perceptual cognition is a type of presentational experience, anubhava, which is defined as experience having intentionality or objecthood, viṣayatā. Perception has both phenomenological character and an epistemological role.

Remarkably, the word ‘perception’ in English shares an ambiguity with its counterpart in Sanskrit, ‘pratyakṣa’, both being used for a mental event, a bit of occurrent knowledge that is perceptual in character, as well as the process that produces it.

The direct results of perception, inference, and testimony count as basic, potentially resolving disagreement without requiring further justification. Inference is the knowledge preceded by perception and can be described as a priori or a posteriori or common scenario. Priori is the knowledge of effect derived from the perception of its cause. For example, upon seeing the clouds, one can infer there will be rain. Posteriori is the knowledge of cause derived from perception of its effect. For example, upon seeing a river swollen one can conclude there was rain.

Nyāya uses two words for inferential knowledge and the inferential process (the former called anumiti, the latter anumāna), as, too, with analogy (upamāna), which generates analogical knowledge (upamiti), and testimony (śabda), which generates testimonial knowledge (śābda-bodha)

The first chapter ends with the basic definitions of mind, body, means of right knowledge, objects of right knowledge, perception, classification of tenets and parameters of conclusion and ascertainment. The second chapter of Book I introduces to concepts and terminologies related to vada- discussion or debates. It emphasizes on various tenets in a debate such as contradiction, proof, wrangling, cavil, etc. It discusses the occasion of rebuke in case one misunderstands the context or does not understand at all.

Subsequent chapters of Nyaya Sutra delve upon the doubts, causes of doubts, their examination and resolution. It says that Examination should be made of each scenario where there is room for doubt. It states that recognition of properties common to many objects are certainly causes of doubt if there is no reference to the precise characters of the object. In the absence of precise knowledge, doubt arises. In terms of debate or trial, doubt is not evident for the disputant or the opponent, while presenting their respective cases, however, the court and audience is thrown into doubt about the actual incidence. Nyaya Sutra discusses in detail about the possibilities of rumor, presumption and probability while examining the correctness of a trial or a situation.

In the third book of Nyaya Sutra, elaborate discussion on mind, body and soul is presented in conjunction with the sensory organs to perception of world. It states that knowledge is momentarily and can evolve or take shapes. The recognition (knowledge) of an object can not take place when mind is drawn by another object. It gives a distinct difference between knowledge and intellect by making a case that if knowledge as a mode of intellect is not different from it, then cessation of recognition(knowledge) should be followed by cessation of intellect. Knowledge belongs neither to sense nor to the object since, knowledge in form of memory is found to abide after sense has perished. It draws a conclusion that Knowledge is nothing but quality of a soul. The body can not be the abode of knowledge as it is a material substance, sense does not possess knowledge it is just an instrument and since mind can not have many perception, hence, knowledge does not belong to mind as well. Hence, knowledge belongs to the soul which is permanent and can perceive a thing now as well as remember a memory from past. The later chapters focus upon pursuit of true knowledge, a brief account of atom in correlation with Vaisesikha principle of philosophies which views atom is the primal object in the world (yes!, 100s of years before the western world laid claim on discovery of atom).

The last books of Nyaya Sutra give the reader an insight about how to act and perceive knowledge and draw conclusions from the presented evidence. It also discusses about development of personality traits such as when to speak or when not to. When there is need to shift a topic or a need to maintain silence. It also reasons with proposition and rebuke on occasions.

Study of Nyaya Sutra gives the readers an impeccable insight into functioning of mind while evaluation of an incident and equips the reader with various traits of debate used by opponents. Nyaya Sutra by Sage Gautama Akasapada establishes not only the literary contribution of India to the science of Epistemology but also underlines the core aspect of Indic civilization to make room for all aspects of thoughts from different school of philosophies and evaluation based upon merit. The detailed account gives you an insight about the functioning of civilization as a democracy where every aspect of an incident is examined, studied, and debated before drawing out conclusions. It still acts as one of the core foundations of study of Law by various authors across the globe and available commentaries on Nyaya Sutra are evidence to its relevance today.


1. The Nyaya Sutra of Gotama, Translated by Satisa Chandra Vidyabhusana, 1913.

2. Epistemology in Classical India, The Knowledge Sources of the Nyāya School — Stephen Phillips, 2012.

3. Indian logic and atomism_ an exposition of the Nyāya and Vaiçeṣika systems — Arthur Berriedale Keith — Oxford University Press (1921)



Reeshabh Choudhary

Software Architect and Developer | Author : Objects, Data & AI.