Define Abhava.

Abhava, in Indian philosophy, particularly within the context of classical schools like Nyaya and Vaisheshika, refers to the absence or non-existence of a particular entity or quality. It is a term used to denote negation or non-being, emphasizing the idea that certain things or attributes are simply not present in a given context.

In Nyaya and Vaisheshika philosophies, abhava is classified into different types, including:

1. Atyantabhava (Absolute Non-existence): This refers to the complete absence of an entity or quality in all three periods of time – past, present, and future.

2. Anyonyabhava (Mutual Non-existence): This type of abhava asserts the absence of two things in each other. For example, the non-existence of fire in water and vice versa.

3. Pragabhava (Antecedent Non-existence): This refers to the absence of an effect in its cause before the effect comes into existence.

4. Anyadhikaranabhava (Absence in Another Substrate): Denotes the non-existence of a quality in a substrate where it is not present.

The concept of abhava is significant in understanding the nature of reality and causation in these philosophical traditions. It complements the discussion of bhava, which refers to existence or being, and contributes to a nuanced understanding of the intricate metaphysical and epistemological aspects within these classical Indian philosophical systems.