In the cultural climate of the century. Street. C. two other philosophical-religious systems arose in India: Jainism and Buddhism. According to Physicscat, five centuries later (1st century BC) Buddhism was profoundly renewed by the doctrine of the Great Vehicle: the individualistic principle of the attainment of nirvāṇa by the individual with his own effort is replaced by that of charity, which pushes to go out. from one’s individualism to help the unenlightened to reach nirvāṇa through words and actions suited to their needs. The hero of the system is the Bodhisattva, the enlightened one who, having reached the threshold of nirvāṇa, returns to involve the non-enlightened. The new doctrine found its metaphysical elaboration in Mādhyamika school, founded by Nāgārjuna (2nd century AD) who, with a well-argued logic, maintains that nothing can be affirmed in the empirical world; the concepts are all contradictory; things have no nature of their own as they are conditioned by each other; individual being is only appearance; the world is a mere representation of man; at the bottom of all things there is only emptiness. From this metaphysical monism derives the theory of the two truths: the superior truth of reality and the conventional truth of appearances.
When man acquires the certainty that all things are reduced to the one principle of emptiness, absolute and relative, spiritual reality and phenomenal reality are identified. To the monistic concept of emptiness he contrasts a (perhaps 4th century AD), which had as its illustrious representatives the two brothers Asanga and Vasubandhu (early 5th century AD): absolute reality is knowing consciousness (vijñāna) and objects exist only in relation to it. By becoming aware of this truth, man becomes capable of a thought, which is an “act of pure thought” and in that moment phenomenal reality and pain become nirvāṇa. The contribution made by this school to logic is also great: it is possible to distinguish between discursive knowledge and sensitive knowledge, between inference and perception. The first act of knowing, prior to language itself, is the perception of the particular in its individuality; in the second, the discursive image and the word take over the intuition; mental constructions belong to this, while sensations are immediate data of consciousness. The object is first perceived by the senses in itself, then it is known by the intellect according to the forms of universals and words. Materialists (mastika, deniers).
In the field of gnoseology they affirmed that only sensory perception gives knowledge of the truth; they denied the value of inference, of the relationship of cause and effect; they affirmed the spontaneity and accidentality of events excluding any causality of them in a supernatural being. All objects come from four primary and eternal elements: earth, water, air, fire; consciousness itself is formed of these. In the moral field the most extremist deniers did not even admit the existence of good and evil: foolish is to want to free oneself from pain, which is in the nature of the world, and deprive oneself of pleasure, which gives flavor to life; this, on the other hand, must be lived with courage. The materialistic theories were reworked and better adapted to the) and from nyāya logic. Founded by Kaṇāda (perhaps 1st century AD), the school stated that reality can be divided into six categories: substance, quality, activity, generality, particularity, inherence. Of the substances (air, water, earth, fire, ether, time, space, soul, intellect), the first four are made up of atoms, eternal and indivisible. A god (Iśvara) presides over their organization, but he is not their creator. The school also admitted the soul as an eternal and immaterial substance, invisible, but perceptible through cognitive and volitional acts, desire, pleasure, etc. The nyāya (right reasoning) school, founded by Akṣapāda (perhaps 2nd century AD), accepted the Vaiśeṣika metaphysics (not, however, the existence of an ordering god), but he turned his greatest attention to gnoseological problems, elaborating a technical terminology of considerable precision. The fundamental problem of the nyāya is the distinction between true and false knowledge: perception, inference, comparison and testimony lead to true knowledge; false is the knowledge produced by memory, doubt, error and hypothesis. The author of a critique of Buddhist subjectivism and a return to orthodox thought of the Vedas was the mīmāṃsā school, which appeared perhaps between the century II a. C. and the sec. II d. C. and later deepened by Kumarila (VIII century AD) and Prabhākara (VII-VIII century AD): the reality of the empirical world is made up of atoms and is perceived with the senses; the universe is eternal and has life within itself without having to admit a creator god. Knowledge is valid by virtue of its intrinsic reasons, so reasoning only serves to eliminate doubt and prove the falsity of wrong knowledge.