Indian Logic (Nyaya and Allied Systems)
What the exam tests
Indian logic, especially Nyaya, tests the pramanas, the five-membered syllogism, the conditions of valid inference, and hetvabhasa (fallacies). Allied systems-Vaisheshika, Samkhya, Yoga, Mimamsa, Vedanta, Buddhist and Jaina logic-are tested for their distinctive contributions.
Core rules
- Nyaya accepts four pramanas: pratyaksha (perception), anumana (inference), upamana (comparison), and shabda (verbal testimony). Mimamsa adds arthapatti and anupalabdhi.
- Anumana has paksha (subject), sadhya (thing to prove), and hetu (reason). The five members are pratijna (thesis), hetu (reason), udaharana (example), upanaya (application), and nigamana (conclusion).
- A valid hetu must be present in the paksha, present in similar cases, and absent from dissimilar cases (paksha-sapaksha-vipaksha conditions).
- Hetvabhasa: savyabhichara (irregular/inconclusive), viruddha (contradictory), asiddha (unproved), satpratipaksha (counterbalanced), badhita (falsified).
- Vaisheshika categorizes padarthas; Jaina syadvada uses saptabhangi; Buddhist logicians Dignaga and Dharmakirti develop apoha and trairupya.
Worked example
“The hill has fire; because it has smoke; wherever there is smoke there is fire, as in a kitchen; this hill has smoke; therefore the hill has fire.” Pratijna: hill has fire. Hetu: because it has smoke. Udaharana: kitchen example. Upanaya: this hill has smoke. Nigamana: therefore fire. The reason is valid if smoke is invariably accompanied by fire and absent where fire is absent.
Traps
Do not reduce the Nyaya syllogism to the three-line Aristotelian form; the five members have distinct roles. Do not mix up upamana (comparison) with anumana (inference). A reason that is merely probable is savyabhichara, not a valid hetu. Remember that different schools accept different pramana lists.