25  Indian Logic: Means of Knowledge

Indian logic (Tarkashastra or Nyaya Shastra) is the systematic study of valid knowledge and its means. It developed in parallel with Western logic but with a distinct vocabulary and a strong emphasis on epistemology — the means by which knowledge is acquired.

25.1 Four Foundational Concepts

Every act of valid knowing involves four elements.

TipPramana, Pramatr, Prameya, Pramiti
Sanskrit Translation What it refers to
Pramana Means of knowledge The instrument or source of knowledge (perception, inference, etc.)
Pramatr (or Pramata) Knower / Subject The person who knows
Prameya Object of knowledge What is known
Pramiti Valid cognition / Knowledge The resulting valid knowledge itself 

flowchart LR
  PR[Pramatr<br/>Knower] -->|uses| PM[Pramana<br/>Means]
  PM -->|to know| PE[Prameya<br/>Object]
  PE --> PI[Pramiti<br/>Valid knowledge]
    classDef default fill:#003366,color:#ffffff,stroke:#ffcc00,stroke-width:3px,rx:10px,ry:10px;

25.2 Pramana — Definition and Significance

A pramana is that which produces valid knowledge of an object that was previously unknown. The Indian tradition asks: how do we acquire valid knowledge? The answer differs across the philosophical schools.

TipTwo Marks of Valid Knowledge
  • Yatharthata (Correspondence) — the cognition corresponds to the object as it really is.
  • Anubhava (Direct experiencing) — knowledge arises through a means rather than through accident or memory.

25.3 Schools of Indian Philosophy and the Pramanas they Accept

Indian philosophical schools differ in how many pramanas they accept.

TipNumber of Pramanas Accepted by Each School
School Number Pramanas accepted
Charvaka (Lokayata) — materialist 1 Pratyaksha (perception) only
Vaisheshika 2 Pratyaksha, Anumana
Buddhism 2 Pratyaksha, Anumana
Jainism 2 (sometimes 3) Pratyaksha, Paroksha (mediated) — including inference, comparison, testimony
Sankhya 3 Pratyaksha, Anumana, Shabda
Yoga 3 Pratyaksha, Anumana, Shabda
Nyaya 4 Pratyaksha, Anumana, Upamana, Shabda
Prabhakara Mimamsa 5 Pratyaksha, Anumana, Upamana, Shabda, Arthapatti
Bhatta Mimamsa & Advaita Vedanta 6 Pratyaksha, Anumana, Upamana, Shabda, Arthapatti, Anupalabdhi
TipSix Pramanas — Detailed in the Next Topic
  1. Pratyaksha — Perception
  2. Anumana — Inference
  3. Upamana — Comparison / Analogy
  4. Shabda — Verbal Testimony
  5. Arthapatti — Postulation / Presumption
  6. Anupalabdhi — Non-perception / Non-apprehension

25.4 Astika and Nastika Schools

Indian philosophical schools are traditionally classified by their relation to the Vedas.

TipSix Astika and Three Nastika Schools
Group School Founder / Key text
Astika (orthodox; accept Veda) Nyaya Gautama; Nyaya Sutra
Vaisheshika Kanada; Vaisheshika Sutra
Sankhya Kapila; Sankhya Karika
Yoga Patanjali; Yoga Sutra
Mimamsa (Purva) Jaimini; Mimamsa Sutra
Vedanta (Uttara Mimamsa) Badarayana; Brahma Sutra
Nastika (heterodox; reject Veda) Charvaka / Lokayata Brihaspati (traditional)
Buddhism Siddhartha Gautama (Buddha)
Jainism Mahavira (24th Tirthankara)

25.5 Nyaya School and the Logic Tradition

Among the orthodox schools, Nyaya is the principal logic and epistemology school. The Nyaya Sutra of Gautama (also called Akshapada) is the foundational text. Nyaya identifies sixteen padarthas (categories of investigation), the first of which is Pramana.

TipThe Sixteen Padarthas of Nyaya
  1. Pramana (means of knowledge)
  2. Prameya (object of knowledge)
  3. Samshaya (doubt)
  4. Prayojana (purpose)
  5. Drshtanta (example)
  6. Siddhanta (established conclusion)
  7. Avayava (members of inference)
  8. Tarka (hypothetical reasoning)
  9. Nirnaya (decision)
  10. Vada (discussion)
  11. Jalpa (wrangling)
  12. Vitanda (cavil)
  13. Hetvabhasa (fallacious reason)
  14. Chala (quibble)
  15. Jati (futile rejoinder)
  16. Nigrahasthana (defeat)

The four pramanas accepted by Nyaya — pratyaksha, anumana, upamana, shabda — are the core of classical Indian logic and the most heavily examined in NTA Paper-I.

25.6 Three Conditions for Valid Cognition (Nyaya)

For a cognition to count as pramiti (valid knowledge), Nyaya requires:

TipThree Conditions
  1. Yatharthata — the cognition corresponds to its object.
  2. Pravritti samarthya — it leads to successful action when acted upon.
  3. Anubhava — it is direct experience, not memory.

25.7 Practice Questions

Q 01 Vocabulary Easy

In Indian epistemology, the term pramana refers to:

  • AThe knower
  • BThe object of knowledge
  • CThe means or source of valid knowledge
  • DThe result of memory
View solution
Correct Option: C
Pramana = means / source of valid knowledge (perception, inference, etc.). The knower is pramatr; object is prameya; valid knowledge is pramiti.
Q 02 Charvaka Medium

The Charvaka (Lokayata) school accepts how many pramanas?

  • AOne — Pratyaksha (perception) only
  • BTwo — Pratyaksha and Anumana
  • CFour
  • DSix
View solution
Correct Option: A
Charvaka, the materialist school, accepts only pratyaksha (perception) as a valid pramana.
Q 03 Nyaya School Medium

The Nyaya school accepts how many pramanas?

  • ATwo
  • BThree
  • CFour
  • DSix
View solution
Correct Option: C
Nyaya accepts four pramanas: pratyaksha, anumana, upamana, shabda.
Q 04 Astika Schools Medium

Which of the following is not an Astika (orthodox) school of Indian philosophy?

  • ANyaya
  • BSankhya
  • CBuddhism
  • DVedanta
View solution
Correct Option: C
Buddhism is a Nastika (heterodox) school — it does not accept Vedic authority. The six Astika schools are Nyaya, Vaisheshika, Sankhya, Yoga, Mimamsa, Vedanta.
Q 05 Founders Hard

Match the school with its traditional founder / key text:

(i) Nyaya (a) Patanjali
(ii) Yoga (b) Kanada
(iii) Vaisheshika (c) Gautama (Akshapada)
(iv) Sankhya (d) Kapila
  • A(i)-(c), (ii)-(a), (iii)-(b), (iv)-(d)
  • B(i)-(a), (ii)-(b), (iii)-(c), (iv)-(d)
  • C(i)-(b), (ii)-(c), (iii)-(d), (iv)-(a)
  • D(i)-(d), (ii)-(b), (iii)-(a), (iv)-(c)
View solution
Correct Option: A
Nyaya → Gautama; Yoga → Patanjali; Vaisheshika → Kanada; Sankhya → Kapila.
Q 06 Six Pramanas Medium

The six pramanas accepted by Bhatta Mimamsa and Advaita Vedanta include all of the following EXCEPT:

  • APratyaksha
  • BAnumana
  • CSmriti (memory)
  • DAnupalabdhi
View solution
Correct Option: C
The six pramanas are Pratyaksha, Anumana, Upamana, Shabda, Arthapatti, Anupalabdhi. Smriti (memory) is explicitly excluded as a pramana — valid knowledge requires direct experience (anubhava).
Q 07 Padarthas Medium

The Nyaya school identifies how many padarthas (categories of investigation)?

  • ASix
  • BSixteen
  • CTwenty-four
  • DEighteen
View solution
Correct Option: B
Nyaya identifies sixteen padarthas — pramana, prameya, samshaya, prayojana, drshtanta, siddhanta, avayava, tarka, nirnaya, vada, jalpa, vitanda, hetvabhasa, chala, jati, nigrahasthana.
Q 08 Pramatr-Prameya Easy

Match the Sanskrit term with its meaning:

(i) Pramatr (a) Means of knowledge
(ii) Pramana (b) Object of knowledge
(iii) Prameya (c) Knower
(iv) Pramiti (d) Valid knowledge
  • A(i)-(c), (ii)-(a), (iii)-(b), (iv)-(d)
  • B(i)-(a), (ii)-(b), (iii)-(c), (iv)-(d)
  • C(i)-(b), (ii)-(c), (iii)-(d), (iv)-(a)
  • D(i)-(d), (ii)-(c), (iii)-(b), (iv)-(a)
View solution
Correct Option: A
Pramatr → knower; Pramana → means; Prameya → object; Pramiti → valid knowledge.
ImportantQuick recall
  • Four foundational concepts: Pramatr (knower), Pramana (means), Prameya (object), Pramiti (knowledge).
  • Six Astika schools: Nyaya, Vaisheshika, Sankhya, Yoga, Mimamsa, Vedanta.
  • Three Nastika schools: Charvaka, Buddhism, Jainism.
  • Pramanas accepted: Charvaka 1 · Vaisheshika/Buddhism 2 · Sankhya/Yoga 3 · Nyaya 4 · Prabhakara Mimamsa 5 · Bhatta Mimamsa & Advaita Vedanta 6.
  • Nyaya founder: Gautama / Akshapada; text: Nyaya Sutra.
  • Nyaya: 16 padarthas.
  • Memory (smriti) is not a pramana.