1. perception
2. inference
3. comparison or analogy (as a means to acquire new vocabulary)
4. testimony
Perception as a knowledge source requires that a sensation be
veridical;
non-veridical sensations do not count as perception (taken as a
pramana)
Compare:
knowledge (according to Plato, etc.:) which is
(1) a belief
(2) that's true
(3) with justification
Perception (according to Nyaya) is defined as:
(1) a cognition
(2) resulting from sense-object contact or relationality
(3) that is not due to words and
(4) is veridical.
Inference, according to Nyaya's paradigm:
(0) There is fire on yonder hill. (The conclusion to be proved.)
(1) There is smoke rising from it. (A perceptual premise.)
(2) Wherever there's smoke, there's fire. (The general proposition expressing an invariable relationship or ``pervasion.''
(3) The hill falls under the ``wherever'' of the general proposition.
(4) There is fire on yonder hill.
Inferential terms:
(a) the prover or probans (e.g., smoke), the middle term
(b) the probandum, that which is to be proved (e.g., fire), the major term
(c) the subject, the locus where the prover is known to be (e.g., the hill), the minor term
(d) the pervasion, the invariable presence of the probandum wherever there is the prover (e.g., the relation between smoke and fire, such that wherever smoke there fire)
The general proposition expresses an invariable relation in nature, a
pervasion:
Causal relations are examples (necessary and sufficient conditions).
Class inclusions, eliminative arguments, and analogous structures are further examples.
Analogy
Learning what a new word means by having comparisons drawn in terms one already understands.
For example, a gavaya is like a cow but . . .
Testimony (as a
knowledge source, pramana, requires):
(a) that the testifier know what he/she is talking about
(b) that the testifier wants to convey the truth and has no desire to lie or mislead