Indian philosophy, the systems of thought, and reflection that were developed by the civilizations of the Indian subcontinent. They include both orthodox (astika) systems, namely, the Nyaya, Vaisheshika, Samkhya, Yoga, Purva-Mimamsa (or Mimamsa), and Vedanta schools of philosophy, and unorthodox (nastika) systems, such as Buddhism and Jainism. Indian thought has been concerned with various philosophical problems, significant among which are the nature of the world (cosmology), the nature of reality (metaphysics), logic, the nature of knowledge (epistemology), ethics, and the philosophy of religion.

Concepts Schools
Abhava
Abhava means non-existence, negation, nothing, or absence.

It is the negative of Bhava which means being, becoming, existing, or appearance.

The Vaisheshika, the Nyaya, the Bhatta Mimamsa, and Dvaita schools hold Abhava as a distinct category. Recognized as a reality by the Nyaya school, Abhava is often stated to be the reality of the greatest moment in the pluralistic universe and is connected with Mukti.

Anuplabdhi
Anupalabdhi means ‘non-recognition’, ‘non-perception’.

This word refers to the Pramana of Non-perception which consists of the presentative knowledge of negative facts.

According to the Bhatta school of Purva-Mimamsa and Advaita-Vedanta system of philosophy, Anupalabdhi is a way to apprehend an absence; it is regarded as a means of knowledge, the other five being – pratyaksa (‘perception’), anumana (‘inference’), sabda (‘testimony’), upamana (‘comparison’) and arthapatti (‘presumption’). The perception of negation or non-existence in its various forms is also due to the relation of attributiveness.

Apoha
The apoha theory is first and foremost an approach to the problem of universals — the problem of the one over the many.

The apoha theory is a distinctive Buddhist approach to being a nominalist.

Syadavada
Syadvada, in Jaina metaphysics, the doctrine that all judgments are conditional, holding good only in certain conditions, circumstances, or senses, expressed by the word syat (Sanskrit: “may be”). The ways of looking at a thing (called naya) are infinite in number.