Sāṅkhya, Yoga and Nyāya-Vaiśeṣika

Nyāya pramāṇas

Nyāya, as systematised in the Nyāyasūtra attributed to Gotama, recognises four pramāṇas, or valid means of knowledge: pratyakṣa (perception), anumāna (inference), upamāna (comparison) and śabda (verbal testimony). Anupalabdhi (non-apprehension) is accepted as a means of knowledge in Advaita Vedānta and Mīmāṃsā but is not in the Nyāya list, so it must not be taken as a Nyāya pramāṇa. Inference is the most elaborately classified of these. Svārtha anumāna is inference made for one's own conviction, whereas parārtha anumāna is the formal argument given to persuade others. Among the subtypes, pūrvavat infers an effect from its cause, as when dark clouds are taken to signal coming rain, while śeṣavat infers a cause from an observed effect, as when wet streets are taken to show that it rained during the night. Sāmānyatodṛṣṭa rests on observed general concomitance rather than on a specific causal link.

Vaiśeṣika padārthas

Vaiśeṣika is an atomist realist school whose ontology is organised into padārthas, categories of reality. The traditional list has seven members: dravya (substance), guṇa (quality), karma (action), sāmānya (universal), viśeṣa (particularity), samavāya (inherence) and abhāva (non-existence). Guṇa is itself a padārtha, whereas ātman, tejas and vāyu are individual kinds of substance that fall under dravya and are not separate categories. The same analysis is applied to the meaning of a sentence. An affirmative predication such as 'the cup is red' involves a substance, a quality predicated of it, a universal that the substance instantiates, and the inherence relation binding quality and universal to the substance. The meaning of such a sentence therefore consists of dravya, sāmānya, guṇa and samavāya, while karma, viśeṣa and abhāva play no role.

Sāṅkhya evolutes of prakṛti

In Sāṅkhya, prakṛti is the unmanifest primordial matter from which the material world evolves, while puruṣa is conscious and neither produces nor evolves. The evolutionary sequence runs from prakṛti to mahat or buddhi, then to ahaṃkāra. From the sattvic aspect of ahaṃkāra arise the eleven organs, including manas, and from its tamasic aspect arise the tanmātras and gross elements. Manas is therefore an evolute, through ahaṃkāra, of prakṛti, and not of puruṣa or of the guṇas themselves. The ten external instruments, the bāhyakaraṇa, are the five jñānendriyas, which receive sensory data, and the five karmendriyas, which perform actions. Manas, together with buddhi and ahaṃkāra, is internal and belongs to the antaḥkaraṇa rather than to the external organs.

Indian theories of validity and error

Indian epistemologies differ on how the validity and error of a cognition are known. Nyāya and Vaiśeṣika hold that validity is extrinsic (parataḥ-prāmāṇya): a cognition is established as valid through external conditions, such as its correspondence with reality and the success of practical activity based on it. Both schools use a realistic test of correspondence together with a pragmatic test of workability. The contrasting doctrine of intrinsic validity (svataḥ-prāmāṇya) is associated with the Mīmāṃsā schools, and Vaiśeṣika does not accept it. The Nyāya theory of error is anyathākhyāti, the apprehension of something as something other than what it is, as when a shell is taken for silver. Asatkhyāti, the view that the apparent object is non-existent, is the Mādhyamika position. Ātmakhyāti, the view that the object is a mental image, belongs to the Yogācāra school. Vivekakhyāti, the view that error arises from failure to discriminate, is the Sāṃkhya account.

Sāṅkhya antaḥkaraṇa

Sāṃkhya divides its instruments into the external (bāhyakaraṇa), namely the ten indriyas, and the internal (antaḥkaraṇa). The antaḥkaraṇa has three members: buddhi (intellect, which determines and decides), ahaṃkāra (ego, the principle of self-identification) and manas (mind, which coordinates the data of the senses). Buddhi and ahaṃkāra are therefore antaḥkaraṇa, while the jñānendriyas and karmendriyas, being external instruments, are not.

Aṣṭāṅga yoga yama

In Patañjali's Yoga, the eightfold path (aṣṭāṅga yoga) begins with yama, the set of five restraints listed in Yogasūtra II.30: ahiṃsā (non-violence), satya (truthfulness), asteya (non-stealing), brahmacharya (continence) and aparigraha (non-possessiveness). Ahiṃsā, satya and aparigraha are yamas, and so are asteya and brahmacharya. Īśvara-praṇidhāna, devotion to God, belongs to the niyamas, the second limb, and is not a yama. Students should keep these two lists separate when answering questions on the eight limbs.

Patañjali's five kleśas

Patañjali's Yogasūtra (II.3) names five kleśas, afflictions that bind the mind and generate suffering: avidyā (ignorance or false knowledge), asmitā (egoism), rāga (attachment to pleasure), dveṣa (aversion to pain) and abhiniveśa (clinging to life). Avidyā is the root from which the other four arise. Mātsarya, envy or rivalry, is not on this list, although it may be treated as a fault in other contexts.