Nyaya · interactive
How do we know something is true?
Nyaya’s four means of valid knowledge
1
प्रत्यक्ष pratyakṣa
Perception
Knowledge produced by contact of a sense with its object, such as seeing a pot in front of you. Nyaya distinguishes indeterminate perception (bare awareness) from determinate perception (awareness of it as a pot).
2
अनुमान anumāna
Inference
Knowledge of something unperceived through a sign invariably connected with it. The classic case is fire on the hill, known from smoke. The whole weight rests on that invariable concomitance (vyāpti).
3
उपमान upamāna
Comparison
Knowing what a word refers to through similarity. You are told a gavaya (wild ox) looks like a cow, and on meeting one in the forest you know 'this is a gavaya'.
4
शब्द śabda
Testimony
Knowledge from the words of a reliable person (āpta), someone who knows the matter and speaks truthfully. For Nyaya this includes the Veda, which it takes to be authored by a trustworthy speaker, God.
Which pramana is at work?
Choose the means of knowledge in each situation.
You touch the stove and feel that it is hot.
You hear thunder and conclude that rain clouds are overhead.
A friend who has been there tells you the café has closed down, and you believe it.
Told that a zebra looks like a striped horse, you recognise one at the zoo.
You see smoke rising behind the hill and know there is a fire.
The five-membered argument
Inference presented for others (parārthānumāna) proceeds in five steps. The stock example is the smoky hill.
Step 1 · Thesis
The hill has fire.
What is to be proved.
When a reason fails: the fallacies (hetvābhāsa)
सव्यभिचार
Inconclusive reason
The reason occurs both with and without what is to be proved. 'The hill has fire because it is knowable' fails, since lakes are knowable too.
विरुद्ध
Contradictory reason
The reason actually proves the opposite of the thesis.
सत्प्रतिपक्ष
Counterbalanced reason
An equally strong reason supports the contrary conclusion.
असिद्ध
Unproven reason
The reason itself is not established, for instance because the 'smoke' is really mist.
बाधित
Contradicted reason
The conclusion is contradicted by a stronger pramana, such as perception.
How many ways of knowing?
The schools disagree on which pramanas are independent. This is a standard summary; each school has its own detailed arguments.
| School | Perception | Inference | Comparison | Testimony | Postulation | Non-apprehension |
|---|---|---|---|---|---|---|
| CharvakaPerception alone; inference is treated as uncertain. | ● | · | · | · | · | · |
| Buddhist logicians (Dignaga, Dharmakirti) | ● | ● | · | · | · | · |
| Vaisheshika | ● | ● | · | · | · | · |
| Sankhya & Yoga | ● | ● | · | ● | · | · |
| Nyaya | ● | ● | ● | ● | · | · |
| Prabhakara Mimamsa | ● | ● | ● | ● | ● | · |
| Bhatta Mimamsa & Advaita | ● | ● | ● | ● | ● | ● |
| JainismClassifies knowledge as direct (pratyaksha) or indirect (paroksha), and counts sensory perception as indirect in the strict sense. | ● | · | · | · | · | · |
- अर्थापत्तिPostulation
- Assuming what must be true to explain a fact. Devadatta is fat but never eats by day, so he must eat at night.
- अनुपलब्धिNon-apprehension
- Knowing an absence from its non-perception, as in 'there is no pot on this floor'.
- परोक्षIndirect knowledge
- In Jain epistemology, all knowledge mediated by the senses or by signs.