The sūtras are commented by a major philosopher in the respective traditions to elaborate upon the established doctrine by quoting from the śāstras (scriptures) and using logic and pramāṇas (accepted source of knowledge).
For example, in the tradition of Vedanta, the author of the Brahma Sūtra was Veda-Vyāsa and the commentators were Ādi Śaṅkara, Rāmānuja and Mādhavācārya (each of whom eventually set up sub-schools within Vedānta).
Indian works which discuss various competing doctrines include the Kathavatthu, the Mahavibhasa, Bhaviveka's Blaze of Reasoning and Shantaraksita's Tattvasamgraha.
[3] Tibetan Buddhists developed the genre further and numerous siddhānta works were written by figures such as Rongzompa, Chekawa Yeshe Dorje, Sakya Pandita, Longchenpa, Jamyang Shéba, and Changkya Rölpé Dorjé.
In Indian astronomy and astrology, Siddhanta (or Siddhantic) refers to a genre of texts that replaced the earlier tradition based on the Vedanga Jyotisha.