Study Notes on Indian Logic for Paper-1

By Ashwani Tyagi|Updated : August 20th, 2021


  • Nyaya is the name given to one of the six orthodox schools of Hindu philosophy—specifically the school of logic.
  • The Nyaya school of philosophical speculation is based on texts known as the Nyaya Sutras, which were written by Aksapada Gautama from around the 2nd century CE.
  • Nyaya differs from Aristotelian logic in that it is more than logic in its own right.
  • Its followers believed that obtaining valid knowledge was the only way to obtain release from suffering.
  • They, therefore, took great pains to identify valid sources of knowledge and to distinguish these from mere false opinions.
  • Nyaya is thus a form of epistemology in addition to logic.
  • According to the Nyaya school, there are exactly four sources of knowledge (pramanas): perception, inference, comparison, and testimony.
  • Knowledge obtained through each of these can, of course, still be either valid or invalid. As a result, Nyaya scholars again went to great pains to identify, in each case, what it took to make knowledge valid, in the process creating a number of explanatory schemes. In this sense, Nyaya is probably the closest Indian equivalent to contemporary analytic philosophy.


  • The Nyaya epistemology considers knowledge (jñāna) or cognition (buddhi) as apprehension (upalabdhi) or consciousness (anubhava).
  • Knowledge may be valid or invalid.
  • The Naiyayikas (the Nyaya scholars) accepted four valid means (pramaṇa) of obtaining valid knowledge (prama) - perception (pratyakṣa), inference (anumāna), comparison (upamāna) and verbal testimony (śabda).
  • Invalid knowledge includes memory (smṛti), doubt (saṁśaya), error (viparyaya) and hypothetical reasoning (tarka).


  • Pratyakṣa (perception) occupies the foremost position in the Nyaya epistemology.
  • Perception is defined by Akṣapāda Gautama in his Nyaya Sutra as a 'non-erroneous cognition which is produced by the intercourse of sense-organs with the objects, which is not associated with a name and well-defined'.
  • Perception can be of two types, laukika (ordinary) and alaukika (extraordinary).


  • 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


  • Upamāna, which can be roughly translated as the comparison is the knowledge of the relationship between a word and the object denoted by the word.
  • It is produced by the knowledge of resemblance or similarity, given some pre-description of the new object beforehand.

Verbal testimony

  • Śabda or verbal testimony is defined as the statement of a trustworthy person (āptavākya), and consists in understanding its meaning.
  • It can be of two types, Vaidika (Vedic), which are the words of the four sacred Vedas, and are described as the Word of God, having been composed by God, and Laukika, or words and writings of trustworthy human beings.
  • While Vaidika testimony is perfect because the Vedas are spoken by God, Laukika testimony are is not infallible.

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We hope you all understood the Study Notes on Indian Logic for Paper-1 for UGC NET Exam 2021.

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Ashwani TyagiAshwani TyagiMember since Jun 2020
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Farhat Fatma

Farhat FatmaJan 19, 2021

Sir plss hindi me
Radha Sharma

Radha SharmaJan 20, 2021

Sir Hindi me study notes mil skte hai?
Divya Jangid

Divya JangidJan 20, 2021

Hindi m b notes dijiye..... Sir

MonikaJan 20, 2021

Thanks sir 🙏
Rajib Sau

Rajib SauJan 31, 2021

Indian logic ki notes
Anchal Sain

Anchal SainMar 26, 2021

Sir Hindi me study notes nhi h kya
Kalu Ram Jangir
Please give in hindi
Sir English to Hindi  me v diya kije plz

ShamaMar 27, 2021

Sir notes hindi me provide kra daina just pllllzzzz

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