The characteristic of these schools is that they may belong to one "masthead" and disagree with each other, or be in agreement while professing allegiance to different banners. An example of the latter is the non-Vedic Jain and the Vedic Samkhya schools, both of which have similar ideas on pluralism; an example of the former would be the Dvaita and the Advaita schools, both of whom are Vedic. However, every school has subtle differences.
Competition between the various schools was intense during their formative years, especially between 800 BC to 200 AD. Some like the Jain, Buddhist, Shaiva and Advaita schools survived, while others like Samkhya and Ajivika did not.
The Sanskrit term for "philosopher" is , one who is familiar with the systems of philosophy, or .
The earliest mention of this appears in the Rig Veda, which speaks of the Brahman, or the universally transcendent and "ethereal" building block of all the world. It is described as dimensionless, timeless and beyond reach of the known frontiers of happiness and knowledge.
The idea of , translated as "righteousness" or "the cosmic and social order" by Gavin Flood, also plays an important role.
pre-300 BC - the rise of the orthodox Darshanas
Many Hindu intellectual traditions were codified during the medieval period of Brahmanic-Sanskritic scholasticism into a standard list of six orthodox (astika) schools (darshanas), the "Six Philosophies" all of which cite Vedic authority as their source:
These are often coupled into three groups for both historical and conceptual reasons: Nyaya-Vaishesika, Samkhya-Yoga, and Mimamsa-Vedanta.
The six systems mentioned here are not the only orthodox systems, they are the chief ones, and there are other orthodox schools such as the "Grammarian" school.
The Vedanta school is further divided into six sub-schools: Advaita (monism/nondualism), Visishtadvaita (monism of the qualified whole), Dvaita (dualism), Dvaitadvaita (dualism-nondualism), Suddhadvaita, and Achintya Bheda Abheda schools.
Schools that do not accept the authority of the Vedas are defined by Brahmins to be unorthodox (nastika) systems.
Jains however believe that the Jaina philosophy was in fact revived by Mahavira, whom they consider as the 24th and final Jain Tirthankars (enlightened seers), a line that stretches to time immemorial. The 23rd seer, Parsva may be dated to around 900 B.C.
Jainism may not be a part of the Vedic Religion (Hinduism), , even as there is constitutional ambiguity over its status. Jain tirthankars find exclusive mention in the Vedas and the Hindu epics. During the Vedantic age, India had two broad philosophical streams of thought: The Shramana philosophical schools, represented by Buddhism Jainism, and the long defunct Samkhya and Ajinkya on one hand, and the Brahmana/Vedantic/Puranic schools represented by Vedanta, Vaishnava and other movements on the other. Both streams are known to have have mutually influenced each other.
The Hindu scholar, Lokmanya Tilak credited Jainism with influencing Hinduism in the area of the cessation of animal sacrifice in Vedic rituals. Bal Gangadhar Tilak has described Jainism as the originator of Ahimsa and wrote in a letter printed in Bombay Samachar, Mumbai:10 Dec, 1904: "In ancient times, innumerable animals were butchered in sacrifices. Evidence in support of this is found in various poetic compositions such as the Meghaduta. But the credit for the disappearance of this terrible massacre from the Brahminical religion goes to Jainism."
Swami Vivekananda also credited Jainsim as one of the influencing forces behind the Indian culture.
A Jain is a follower of Jinas, spiritual 'victors' (Jina is Sanskrit for 'victor'), human beings who have rediscovered the dharma, become fully liberated and taught the spiritual path for the benefit of beings. Jains follow the teachings of 24 special Jinas who are known as Tirthankars ('ford-builders'). The 24th and most recent Tirthankar, Lord Mahavira, lived in c.6th century BC, which was a period of cultural revolution all over the world. Socrates was born in Greece, Zoroaster in Persia, Lao‑Tse and Confucious in China and Mahavira and Buddha in India. The 23rd Thirthankar of Jains, Lord Parsvanatha is recognised now as a historical person, lived during 872 to 772 B.C.. . Jaina tradition is unanimous in making Rishabha, as the First Tirthankar.
One of the main characteristics of Jain belief is the emphasis on the immediate consequences of one's physical and mental behavior. Because Jains believe that everything is in some sense alive with many living beings possessing a soul, great care and awareness is required in going about one's business in the world. Jainism is a religious tradition in which all life is considered to be worthy of respect and Jain teaching emphasises this equality of all life advocating the non-harming of even the smallest creatures.
Non-violence (Ahimsa) is the basis of right View, the condition of right Knowledge and the kernel of right Conduct in Jainism.
Jainism encourages spiritual independence (in the sense of relying on and cultivating one's own personal wisdom) and self-control (व्रत, vratae) which is considered vital for one's spiritual development. The goal, as with other Indian religions, is moksha which in Jainism is realization of the soul's true nature, a condition of omniscience (Kevala Jnana). Anekantavada is one of the principles of Jainism positing that reality is perceived differently from different points of view, and that no single point of view is completely true. Jain doctrine states that only Kevalis, those who have infinite knowledge, can know the true answer, and that all others would only know a part of the answer. Anekantavada is related to the Western philosophical doctrine of Subjectivism.
From its inception, Buddhism has had a strong philosophical component. Buddhism is founded on the rejection of certain orthodox Hindu philosophical concepts. The Buddha criticized all concepts of metaphysical being and non-being, and this critique is inextricable from the founding of Buddhism.
Buddhism shares many philosophical views with Hinduism, such as belief in karma, a cause-and-effect relationship between all that has been done and all that will be done. Events that occur are held to be the direct result of previous events. The ultimate goal for both Hindu and Buddhist practitioners is to eliminate karma (both good and bad), end the cycle of rebirth and suffering, and attain freedom (Moksha or Nirvana). However, a major difference is the Buddhist rejection of a permanent, self-existent soul (atman). This view is a central one in Hindu thought but is rejected by all Buddhists.
The political philosophy most closely associated with India is the one of ahimsa (non-violence) and Satyagraha, popularized by Mahatma Gandhi during the Indian struggle for independence. It was influenced by the Indian Dharmic philosophy (particularly the Bhagvata Gita) and Jesus, as well as, secular writings of authors such as Leo Tolstoy, Henry David Thoreau and John Ruskin. In turn it influenced the later movements for independence and civil rights, especially those led by Nelson Mandela and Martin Luther King, Jr.