According to various schools of Indian philosophy, we can infer that there is one or more ultimate realities in the universe. By the term ultimate reality, we generally mean something that exists by itself, without relying on anything. All philosophical systems of India have admitted the existence of at least one Ultimate Reality. Thus, Advaita Vedanta has Nirguna Brahman; Nyaya – Vaiseshika have single God and eternal atoms; Samkhya propose two ultimate realities, Purusha and Prakriti. The Mahayanist’s theories in Prajna and Vijnaptimatra are akin to the belief in an ultimate reality.
A classification of Indian philosophical systems based on their concept about the ultimate reality (or realities) is possible and it will be helpful in understanding the articles (or) chapters to be followed.
Carvākās or Lokāyata considers Matter as the only ultimate reality. Perception is the sole Pramāna (means of knowledge). Earth, water, air and fire are the four primary elements. Consciousness is the product of these material elements, combined in specific proportions, just like how intoxication is produced by mixing a number of ingredients, which by themselves are not intoxicants.
There is a disagreement among the Cārvākas on defining the soul. Assumptions and verses are not considered as means of knowledge. Some believe that human body itself is the Soul where as others are of the opinion that the mind, senses and the Prana comprises the Soul. The Carvaka’s idea about Soul is that, it is not an eternal thing and it perishes with the death of the human body.
Cārvākas do not believe in afterlife. Death itself is the emancipation. They advocate on making the most out of your life here. There is no strict enforcing of any moral conducts as per their view, however it should not be mistaken for a system of anarchy or considered anti law rather the system advice the followers to have a set of conducts and moral standards which is most suitable for them. It can be assumed that the cause-effect relation, which is limited to this world is perhaps accepted by them.
Dualists say that there are two irreducible ultimate realities. In Indian philosophy, Samkhya system is dualistic. It posits two Ultimate realities – Prakriti and Purusha. Each one can’t reduce to the other. Here Prakriti is by default is inanimate, but association with Purusha gives ‘life’ to it and it starts to evolve for the Purusha. This will be explained in detail in another chapter.
Realist philosophical schools say that external world has an independent existence apart from the mind of the seer (one who sees). Perceived objects and the Perceiver have independent existences. Suppose a seer views a tree. Then seer and the tree, both are real. Existence of the tree does not depend on the seer. To have a mental impression of the tree in the seer’s mind, a tree existing outside the seer’s body is must. This is the idea put forward by the realist.
In Indian philosophy Samkhya, Yoga, Nyaya, Vaiseshika, Purva mimamsa, Vaibhasika, Sautrantika, and Jains are the popular realist schools.
In Idealism, mind is the only reality. Existence of an external world depends upon the seer’s mind. When we see a tree; as per idealism, it is a projection of the mind. External tree is rooted in our thought. External world is nothing, but a stream of such thoughts or consciousness continuously flowing into the mind. Avidya is the main reason for the continuous stream of consciousness.
Buddhist Vijnanavada sect is an Absolute Idealistic school of Indian Philosophy.
Pluralist schools approve the existence of multiple eternal realities. Vaiseshika, Nyāya, Jaina, etc are the advocates of pluralism in Indian Philosophy. They state that there are innumerable atoms, which combine in certain proportions to form the aggregates. Thus they are atomists too. They say multiple souls exist, which are eternal, just like God. These multiple souls may be qualitatively same or not.
Vaiseshika school are the first advocates of Atomism in world philosophy. Atomism in Indian Philosophy doesn’t start with Rishi Kanada. Most recognized theory is Kanada assembled the then prevalent Atomic theories and arranged & synthesised them into a single and rigid frame work.
This group believes that everything happening in this world is already fixed or predetermined by fate. Future and after-life of human beings is also fixed. We only live according to the decree of fate. Human efforts are insignificant. Efforts cannot change/alter/influence our future life. Ethics need not be practiced as it has no influence on future.
The only fatalist school of Indian Philosophy is Ājīvika. Only limited information is available about them. They are supposed to be linked with Jainism. Their leader Makkali Gosala is considered as the contemporary of Sri Buddha and Mahavira.
Nihilists asserts that ‘Nothing exists’. External world exists in so many relations (dependency) and each relation depends on further relations. This bunch of relations finally leads to full contradictions questioning the existence of every being.
The only nihilistic school of Indian Philosophy is Buddhist Sathyasiddhi School. They are known as Sarva Sunyavadins as per the available sources. Harivarman, who lived before Vasubandhu, is considered as the founder of this sect. Instead of telling that ‘everything is void’, this school says ‘even void does not exist’.
There is a popular belief that Nagarjuna’s Madhyamaka system (Sunyavada) is nihilistic but this does not hold water. Nagarjuna’s usage of word ‘sunya’ does not mean ‘voidness’. Its meaning can be taken as ‘relative’ or ‘indescribable’. Nagarjuna clearly admits an ultimate reality and call it as ‘Prajna’ which is above the momentary phenomenal plane. Prajnaparamita Literature clearly establishes this truth.
Thus Indian Philosophy contains many schools of various thought streams. Such diverse opinions about the existence of reality and the co-existence of all of them for a long time can point to the rich cultural and philosophical excellence of ancient Indians and the liberal atmosphere and mutual respect, under which the various philosophical schools developed their theories and flourished.
 Though both of the terms usually denote the materialist school, there can be certain differences between them. Extreme meager evidences are available about materialist school of Indian philosophy. But in almost all major philosophical works, materialism finds its place, giving the hint that it had adherents at all time in India.
 As per popular opinion, Vijnānavāda advocates subjective idealism. But it is false. Vasubandhu clearly posits an ultimate reality which is unchanging and eternal. He calls it as Vijnāptimātra.
 Read “The Ājīvikas” by Beni Madhav Barua and ‘History and doctrines of the Ājīvikas’ by A L Basham.
 There is almost no literature in India which lists this sect’s philosophy and practice. But Junjiro Takakusu brings some light into their doctrine by citing a Chinese document. Read his book, ‘The Essentials of Buddhist Philosophy’.
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