Nyāya Sūtras 6

Next, inference, which is preceded by that, is of three kinds: with the prior, with the remaining, and commonly seen.

By the phrase "preceded by that," the observation of the relation between the inferential sign and the possessor of the sign, as well as the observation of the inferential sign, are connected.

Through the observation of the inferential sign and the possessor of the sign as related, memory of the inferential sign is connected. Through memory and the observation of the inferential sign, an unperceived object is inferred. "[Inference] having an antecedent" (pūrvavat) is that wherein an effect is inferred from a cause, as [in the case where one infers]: "From the rising of clouds, it will rain."

"[Inference] having a consequent" (śeṣavat) is that wherein a cause is inferred from an effect: having seen the river's water contrary to the previous water, full and swift in current, it is inferred that rain has occurred. "[Inference] based on common observation" (sāmānyatodṛṣṭa): seeing in another place that which was seen elsewhere is preceded by movement;

and so it is with the sun; therefore, even though unperceived, movement of the sun exists.

Alternatively, "having an antecedent" (pūrvavat) is where, between two things that were previously perceived, there is an inference of one through the observation of the other;

an inference of what is not perceived, as of fire by smoke. That called "having a consequent" (śeṣavat) is elimination; and that is the conviction regarding a remaining [alternative] because, when [an alternative] that was applicable is rejected, there is no applicability elsewhere. For instance: when sound—distinguished from universal, particularity, and inherence through being existent, impermanent, and so forth, which are common to substance, quality, and action—is subject to doubt among substance, action, and quality: it is not a substance because it inheres in a single substance; it is not an action because it is the cause of another sound; but that which remains is this [quality]—thus there is the apprehension of sound's being a quality.

That called "based on common observation" (sāmānyatodṛṣṭa) is where, the relation between the inferential sign and the possessor of the sign being imperceptible, the unperceived possessor of the sign is understood through a similarity of the inferential sign to some other object. For instance, the self [is inferred] by desire and so forth: desire and so forth are qualities;

and qualities reside in a substance; that which is their residence is the self. Since [the division] is established merely by stating the classification, the statement "threefold" represents disregard for further brevity of expression by [the author] who considered the instruction of the extensive reasoning of vast scope through a very brief aphorism to be the ultimate brevity of expression. And likewise, this style consisting of such variation in phrasing is a frequent practice in the treatise in the context of established tenets, quibbles, verbal testimony, and so forth.

Perception has the existent as its object, while inference has both the existent and the non-existent as its object. Why? Because it apprehends the three divisions of time:

objects endowed with the three times are grasped by inference: it is inferred that "it will be," that "it is," and that "it was"; and the non-existent is indeed the past and the future. ||5