At the end of an epistemological discussion in a Sanskrit text, it is standard to discuss the sources of knowledge (pramāṇa) you don’t accept. Long-term memory (smṛti) has most likely been already excluded at the beginning, while discussing the definition of pramāṇa, so that it is not mentioned among the specific candidates.

Within Mīmāṃsā, Kumārila excludes (at the end of the discussion on abhāva) sambhava (inclusion) and aitihya (tradition). Within Nyāya, Gautama excludes these two, as well as two sources accepted by Kumārila, i.e. arthāpatti (cogent evidence) and abhāva (absence).

The discussion starts in NS 2.2.1, where an opponent says: “There are not 4 sources of knowledge, because [also] tradition, inclusion, cogent evidence and absence as sources of knowledge”. The discussion then goes on for several pages. NS 2.2.2 says that aitihya is nothing but linguistic communication (śabda) and inclusion is inference (anumāna). This is what Kumārila also says. What is different is that Gautama says that also arthāpatti and abhāva are nothing but inference.

This is remarkable, because the classical position of Nyāya authors (e.g., Jayanta) about absence is that this is known through sense-perception (not inference!). Only after Kumārila’s objections and through Gaṅgeśa etc. they say that in some cases inference is indeed needed (e.g., when you infer now that a certain person was not in a place you visited earlier today).

NS 2.2.3ff focus on arthāpatti, which is now said to be inconclusive (anaikāntika). NS 2.2.7 focuses on abhāva, which is now said to be not a pramāṇa at all, because there is not a corresponding prameya. Please notice that early Nyāya does not accept abhāva as a separate category, whereas this will be later added as the seventh padārtha.

Uddyotakara explains: abhāva is not a source of knowledge, because there is no content for it. Uddyotakara also adds something which seems new, namely that there is indeed a pramāṇa at stake, but that this has as its content something existing (again, weird, given the status of abhāva as padārtha…).

NS 2.2.8 speaks again in favour of abhāva, insofar as it is used to cognise, among marked things, the ones which are not marked.
This seems to prove that abhāva is indeed a source of knowledge, as explained by Vātsyāyana and Uddyotakara. NS 2.2.9 goes back to the problem that there is no prameya for such a pramāṇa.

Uddyotakara on NS 2.2.12 explains that there are only two types of absence (prior and posterior absence). This is relevant, because Kumārila had discussed absence as being four-fold (thus, Uddyotakara clearly did not know this classification, since he does not even take notice of it). Interestingly, Vācaspati, commenting on Uddyotakara, feels the need to add that the fact that he mentions two does not mean that he refutes the others.

What does this all tell us about early Nyāya until Uddyotakara and absence?

• 1. that Uddyoataka only knows a 2-fold classification of abhāva as prameya.
• 2. that an early position saw abhāva as part of anumāna (this seems to be also Uddyotakara’s position at the end of his commentary on NS 2.2.2).
• 3. that abhāva is considered a useful epistemological category, e.g., to speak about things lacking a certain characteristic.

The above is based on the commentary on NS 2.2.1–12. I will come back to later passages of the NV.

Addendum: Jhā translates abhāva as “antithesis”. Don’t ask me why.