There are six philosophical systems (darshanas) deemed to be orthodox because they accept the truth and authority of the Vedic revelation. These are as follows:
- The Nyaya based on the Nyaya Sutras of Gautama, in which it is claimed that the existence of God can be proved by logical inference.
- The Vaisheshika based on the Vaisheshika Sutras of Kanada, which argue that everything that exists is to be understood as a reformulation of atoms, which are the basic unit of all things.
- The Mimamsa based on the Mimamsa Sutras of Jaimini, which emphasise the importance of the Vedic rituals, which yield tangible results.
- The Vedanta based on the Vedanta Sutras of Badarayana but which also accept the revelation of the Upanishads and the Bhagavad-gita.
- The Samkhya based on the Samkhya Karika of Ishvarakrishna.
- The Yoga based on the Yoga Sutras of Patañjali.