The first two are undisputed epistemic sources (pramāṇa), where śruti holds the ultimate or supreme authority as Śāstra pramāṇam, while there is difference of opinion for ācāra and ātmatuṣṭi.
[5] In late and post Vedic literature of Hinduism, Shastra referred to any treatise, book or instrument of teaching, any manual or compendium on any subject in any field of knowledge, including religious.
[5] It is often a suffix, added to the subject of the treatise, such as Yoga-Shastra, Nyaya-Shastra, Dharma-Shastra, Koka- or Kama-Shastra,[6] Moksha-Shastra, Artha-Shastra, Alamkara-Shastra (rhetoric), Kavya-Shastra (poetics), Sangita-Shastra (music), Natya-Shastra (theatre & dance) and others.
[10][note 1]Sruti, smriti, ācāra and ātmatuṣṭi are also the four sources of dharma in classical Hindu law, as expressed in Bhavishya Purana, Brahmaparva, Adhyaya 7: vedaḥ smṛtiḥ sadācāraḥ svasya ca priyamātmanaḥetaccaturvidhaṃ prāhuḥ sākshāddharmasya lakshaṇamVedas, smritis, good (approved) tradition and what is agreeable to one's soul (conscience),the wise have declared to be the four direct evidences of dharma.
Smriti literally means "that which is remembered" and it a body of Hindu texts usually attributed to an author, traditionally written down, in contrast to Śrutis (the Vedic literature) considered authorless, that were transmitted verbally across the generations and fixed.
[13] This corpus includes, but is not limited to the six Vedāngas (the auxiliary sciences in the Vedas), the Itihasas (i.e. the Mahābhārata and Rāmāyana), the Dharmasūtras and Dharmaśāstras (or Smritiśāstras), the Arthasaśāstras, the Purānas, the Kāvya or poetical literature, extensive Bhasyas (reviews and commentaries on Shrutis and non-Shruti texts), and numerous Nibandhas (digests) covering politics, ethics (Nitisastras),[26] culture, arts and society.
[14][22] The authors of 18 smritis are namely, Atri, Viṣṇu, Hārīta, Auśanasī, Āngirasa, Yama, Āpastamba, Samvartta, Kātyāyana, Bṛhaspati, Parāśara, Vyāsa, Śaṅkha, Likhita,[note 8] Dakṣa, Gautama, Śātātapa and Vaśiṣṭha.
[note 11]Vyāsasmṛti (verse 1.5) state that śrutismṛtipurāṇokta dharmayogyāstu netare The sayings of Vedas, smṛtis and puranas are deemed to be dharma and not others.
Although in Dharmaśāstra the ideal person who defines the ācāra of a particular place is dictated as one who knows the Vedas or is “learned”, in actual practice this role is often deferred to group leaders along with Vedic scholars.
[35] Ācāra is theologically important in classical Hindu law because it is considered, along with the Vedas (Śruti), and Smriti (traditional texts such as the Dharmaśāstra literature), to be one of the sources of dharma.
[38] Vaśiṣṭhasmṛti verse 1.4 quotes, tadalabhe śiṣṭāchārah pramāṇam, i.e. only if the relevant references are absent in those both, then Śiṣṭa Āchāra can be considered as Antepenultimate pramāṇa.
[46] Yājñavalkya goes further step adding good intent (samyaksaṃkalpa) as additional fifth source of Dharma: śrutiḥ smṛtiḥ sadācāraḥ svasya ca priyam ātmanaḥ samyaksaṃkalpajaḥ kāmo dharmamūlaṃ idaṃ smṛtam The source of dharma is declared to be fivefold: 1) śrutiḥ; 2) smṛtiḥ; sadācāraḥ (right conduct); svasya ca priyam ātmanaḥ (one's own benefit) and5) desire born of purposeful intention (samyaksaṃkalpajaḥ kāmaḥ).
[47][note 17]Later, samyaksaṃkalpa (Pali: sammā saṅkappa) was included among the Noble Eightfold Path (āryāṣṭāṅgamārga) putforth by Gautama Buddha.
In Āpastambasmṛti, it is mentioned as śrutismṛtipurāṇeṣu viruddheṣu parasparampūrvaṃ pūrvaṃ balīyam syāditi nyāyavido viduḥ Whenever there is mutual conflict between vedas, smṛtis and purāṇas, then the ones well-versed in nyāya suggest thatmore preceding epistemic source holds higher weightage (than the later epistemic one)[note 19]Vedavyasa also holds a similar view in his vyāsasmṛti, verse 1.4 śruti smṛti purāṇām virodho yatra driśyate tatra śrotam pramāṇāstu tayordhvyadhe smṛtirvarā In cases where conflicts are apparent among veda, smriti and Purana, Veda is the valid authority; and where remaining two (Smriti and Purana) are in conflict, Smriti is the valid authority[51][note 20]The Prasthanatrayi (Sanskrit: प्रस्थानत्रयी, IAST: Prasthānatrayī) are the three canonical texts of Hindu theology having epistemic authority, especially of the Vedanta schools, namely the Upanishads, the Brahma Sutras, and the Bhagavad Gita.
Adi Sankara who propagated Advaita has established the concept of Prasthanatrayi, the epistemic references based on Śāstra pramāṇam in Hinduism.
Baba Saheb Ambedkar has criticized the rigidity of śāstra pramāṇam in Hinduism in his work Annihilation of Caste by attacking especially on Manusmriti.