Hindu philosophy

Hindu philosophy or Vedic philosophy is the set of philosophical systems that developed in tandem with the first Hindu religious traditions during the iron and classical ages of India. In Indian philosophy, of which Hindu philosophy is a prominent subset, the word used for philosophy is Darshana (Sanskrit: दर्शन; meaning: "viewpoint or perspective"), from the Sanskrit root 'दृश' (drish) meaning 'to see, to experience'.

The schools of thought or Darshanas within Hindu philosophy largely equate to the six ancient orthodox schools: the āstika (Sanskrit: आस्तिक) schools, defined by their acceptance of the Vedas, the oldest collection of Sanskrit texts, as an authoritative source of knowledge. Of these six, Samkhya (सांख्य) is the earliest school of dualism; Yoga (योग) combines the metaphysics of Samkhya with meditation and breath techniques; Nyaya (न्याय) is a school of logic emphasising direct realism; Vaisheshika (वैषेशिक) is an offshoot of Nyaya concerned with atomism and naturalism; Mimamsa (मीमांसा) is a school justifying ritual, faith, and religious obligations; and Vedanta (वेदान्त) contains various traditions that mostly embrace nondualism.

The Indian philosophical landscape during the ancient and medieval periods also produced philosophical systems that share many concepts with the āstika traditions, yet at the same time reject or oppose several central Vedic concepts, such as Ātman, or interpret them in their own way, as is evident in the case of the Ājīvikas. These have been called nāstika (heterodox or non-orthodox) philosophies, and they include: Buddhism, Jainism, Charvaka, Ajivika, and others. Western scholars have debated the relationship and differences within āstika philosophies and with the nāstika philosophies, starting with the writings of Indologists and Orientalists of the 18th and 19th centuries, based on limited availability of Indian literature and medieval doxographies. The various sibling traditions included in Indian philosophies are diverse and are united by: shared history and concepts, textual resources, ontological and soteriological focus, and cosmology. Some heterodox (nāstika) traditions such as Charvaka are often considered as distinct schools within Hindu philosophy because the word Hindu is an exonym historically used as a geographical and cultural identifier for people living in the Indian subcontinent.

Hindu philosophy also includes several sub-schools of theistic philosophies that integrate ideas from two or more of the six orthodox philosophies. Examples of such schools include: Pāśupata Śaiva, Śaiva siddhānta, Pratyabhijña, Raseśvara and Vaiṣṇava. Some sub-schools share Tantric ideas with those found in some Buddhist traditions, which are nevertheless found in the Puranas and the Āgamas. Each school of Hindu philosophy has extensive epistemological literature called Pramana, as well as theories on metaphysics, axiology, and other topics.

In the history of India, the six orthodox schools had emerged before the start of the Common Era, and some schools emerged possibly even before the Buddha. Some scholars have questioned whether the orthodox and heterodox schools classification is sufficient or accurate, given the diversity and evolution of views within each major school of Indian philosophy, with some sub-schools combining heterodox and orthodox views.

Since ancient times, Indian philosophy has been categorised into āstika and nāstika schools of thought. The orthodox schools of Indian philosophy have been called ṣaḍdarśana ('six systems'). This schema was created between the 12th and 16th centuries by Vedantins. It was then adopted by the early Western Indologists, and pervades modern understandings of Indian philosophy. Satoshi Ogura thus warns that we should keep in mind the tendency of classification of Indic knowledge in Persianate discourses and its legacies in modern writings in both India and the Western world.

There are six āstika (orthodox) schools of thought. Each is called a darśana, and each darśana accepts the Vedas as authority. Each āstika darśana also accepts the premise that Atman (eternal Self) exists. The āstika schools of philosophy are:

Schools that do not accept the authority of the Vedas are nāstika philosophies, of which four nāstika (heterodox) schools are prominent: