The Bhāṭṭa and Prābhākara schools of Mīmāṃsā held significant debates regarding the nature of Non-existence (Abhāva) and its valid means of knowledge (pramāṇa).

Nature of Abhāva:

• Prābhākara Mīmāṃsā: Rejects Abhāva as a distinct, independent category of reality (padārtha). For them, non-existence is not a separate entity; it is simply the existence of the substratum or the absence of a positive counter-entity. For example, "there is no pot on the floor" simply means the floor exists, and a pot is not present there; the absence itself is not a separate existent.

• Bhāṭṭa Mīmāṃsā: Accepts Abhāva as a distinct, real category of reality (padārtha), alongside positive categories like substance and quality. They argue that absence is a positive fact about the world that can be directly apprehended.

Knowledge of Abhāva (Pramāṇa):

• Prābhākara: Since abhāva is not a separate entity, it cannot be known by a distinct pramāṇa. Knowledge of absence is implicitly derived from the perception (pratyaksha) of the substratum. Seeing an empty floor is sufficient to know the absence of a pot; no separate cognitive act for absence is needed.

• Bhāṭṭa: Posits Anupalabdhi (non-apprehension) as a distinct and independent pramāṇa for knowing abhāva. They argue that when we do not perceive an object (e.g., a pot) in a place where it could normally be perceived, despite having all the necessary conditions for perception, this very non-perception directly reveals the non-existence of that object. It is a positive cognitive act that specifically apprehends absence.

This debate highlights fundamental differences in their ontological commitments (what exists) and epistemological frameworks (how we know what exists, or what does not).