The Navya-Nyāya darśana (system/school) of Indian logic and philosophy was founded in the 13th century by the philosopher Gangeśa Upādhyāya. Other influences were the work of earlier philosophers Vācaspati Miśra (900–980 CE) and Udayana (10th century). Nyaya means correct thinking with proper arguments & valid reasoning. Its goal is “acquiring knowledge of the reality”. It remained active in India to the 18th century.

Introduction to Knowledge Representation and Navya Nyaya - by Dr. Shrinivasa Varakhedi

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Nyaya Philosophy

Following Text is by Vikas Dhavaria from his Dhavaria blog:

1.1 Introduction

  • Nyaya school is founded by sage Gautama (Aksapada).
  • Nyaya means correct thinking with proper arguments and valid reasoning.
  • Known as:
    • Tarakshashtra (The science of reasoning)
    • Pramanashashtra (The science of logic and epistemology)
    • Hetuvidya (The science of causes)
    • Vadavidya (The science of debate)
    • Anviksiki (The science of critical study)
  • Its goal is “acquiring knowledge of the reality”.

1.2 Epistemology

Nyaya school of thought is adhered to atomistic pluralism and logical realism.

Atomistic Pluralism

  • atom is the constituent of matter,
  • they are not one but many entities,
  • both material and spiritual,
  • as ultimate constituents of the universe.

Logical Realism

  • world exist independently of our perception and knowledge.
  • Independent existence of the world can be defended by logical argument and critical reflection on the nature of experience.

The Nyaya philosophy recognized sixteen categories and the first category is known as “Pramana” which focuses the logical and epistemological character of the Nyaya system.

Pramanas – Four independent pramanas (sources of valid knowledge)

  1. Perception
  2. Inference
  3. Comparision
  4. Verbal testimony or sabda

Knowledge may be treated as cognition, apprehension, consciousness, manifestation of objects. Knowledge is of subjective and objective.

Subjective knowledge –

  • Different people
  • Different opinion
  • Particular subject

Objective knowledge –

  • Different people
  • Similar opinion
  • Particular subject

Knowledge may be valid (prama) or invalid (aprama).

Valid knowledge (Prama)

  • True and right apprehension of an object.
  • Manifestation of object as it is.
  • Consequence of the correspondence theory of truth – truth is the correspondence between a proposition and reality.
  • Presentative knowledge.
  • Object of knowledge is directly present to the knower.
  • Produced by four valid sources of knowledge-
    1. Perception
    2. Inference
    3. Comparision
    4. Sabda

Invalid knowledge (Aprama)

  • Wrong apprehension of object
  • It includes-
    • Memory (smriti) – representative knowledge
    • Doubt (samasya) – lack of certinity
    • Error (viparyaya) – misapprehension
    • Hypothetical reasoning (tarka) – invalid knowledge

Consider the four valid sources of knowledge (pramanas) that is upheld by the Nyayikas.

1. Perception

Direct and immediate cognition produced by the interaction between the object and sense-organs.

Four elements are necessary:

  1. self
  2. mind
  3. sense organs
  4. objects



Two types of perception:

  1. Ordinary perception (laukika)
  2. Extra ordinary perception (alaukika)

Ordinary Perception (two types – external and internal)

  • External perception (bahya)
    • five sense organs
      1. auditory
      2. visual
      3. tactual
      4. gustatory
      5. olfactory
  • Internal perception (manas)
    • only mind and object (example: feeling, desiring, wishing etc.)

Again, perceptions are divided in three sorts-

  1. Indeterminate perception (nirvikalpa)
    • when we can not determine its features like color, shape, size etc.
  2. Determinate perception (savikalpa)
    • when the knowledge of an object consists of characters, such as; name, color, shape etc.
  3. Recognition (prativijnana)
    • the senses contact with the object and recalled that whether the same object had been encountered earlier or not.

Extra ordinary perception

It is a perception that provides knowledge even without the senses object contact.

Three types of extra ordinary perception

  1. Samanyalaksana
    • perception of universals or classess
    • all the particulars belonging to same class
  2. Jnanalaksana
    • an object is not directly presented to the sense organs, but it is retrived in memory through the past cognition of it and is perceived through representation.
    • example: the ice looks cold, the fire looks hot etc.
  3. Yogaja
    • yogis through their power of meditation can have intuitive and immediate perception of all objects, past, present and future.

2. Inference (anumana)

anumana, anu (after) + mana (cognition)

Anumana or inference is such knowledge which follows from other knowledge.

Constituents of inference

An inference is constituted with at least three sentences and these

  • three sentences
    1. major premise
    2. minor premise
    3. conclusion

are again constituted of

  • three different terms
    1. major term
    2. minor term
    3. middle term

Major Premise : All things which have smoke (middle/hetu) have fire (major/sadhya).
Minor Premise : This hill (minor/paksha) has smoke (middle/hetu).
Conclusion : Therefore, this hill has fire.

  • Major term or Sadhya is found in the major premise. Not perceived but it is inferred by us.
  • Minor term or Paksha is found in minor premise. Perceived but not inferred by us.
  • Middle term or Hetu is found in both premises. Establish a relation between Sadhya and Paksha.

In an inference, knowledge of and object is derived due to previous knowledge of some sign or mark. The previous knowledge is due to the universal relation between the major term and the middle term is being present in the minor term.

Types of Inference

  1. Svartha or for one’s self
  2. Parartha of for other

Inference for others consists of five constituents:

  1. This hill has fire (Pratijna).
  2. Because there is smoke (Hetu).
  3. Wherever there is smoke, there is fire (Udaharana).
  4. This hill has smoke (Upamana).
  5. Therefore, this hill has fire (Nigamana).

Smoke, the middle term appears three times. Therefore, it is also known as “tritiyanlinga paramarsa”.

3. Upamana (Comparison)

Upa (similarity) + mana (cognition) means… the similarity between the things and objects.

Four steps involved:

  1. Authoritative statement or description of object (Describe a squirrel)
  2. One observes any such object. (Observe an animal)
  3. Recollection of description. (Recall the description of squirrel)
  4. Resulting knowledge… object is same as described. (Observed animal is squirrel)

4. Verbal Testimony (Sabda)

Sabda is the instructive assertion of a reliable person.

Example: A local fisherman tells about the depth of river.

Kinds of Sabda:

Based on objects of meaning-

  1. Drustartha – deals with perceptible object. Table is brown.
  2. Adrustartha – deals with imperceptible object. Truth is noble.

Based on the origin of words-

  1. Laukika – secular. Only the words of trustworthy person.
  2. Alaukika – Divine or Vaidika.

1.3 Theory of causation (Asatkaryavada/Armbhavada)

Two important components in this theory:

  1. Cause – an unconditional and invariable antecedent of an effect.
  2. Effect – an unconditional and invariable consequent of a cause.

Effect is produced by a cause but the effect and the cause are not one and the same.

Effect is a new product comes to the existence.

1.4 Self and liberation

Infinite numbers of self exists in the universe.


  1. neither be identified with mind
  2. nor with pure consciousness
  3. but a consciousness belonging to an individual.

Self (no consciousness) when comes to contact with sense organs = Acquires consciousness. This acquiring produces bondage, hence aspires for liberation or salvation.


  1. The state refrain from all kinds of sufferings, cycle or birth and death.
  2. Can be achieved when there is cessation of karmic chain or karmic influx.

1.5 The concept of God


  1. Creator, sustainer and destroyer.
  2. Efficient cause (not the material) of universe.
  3. Desires the universe remain in the state of stability and tranquillity.
  4. Omnipresent and omniscient being.

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