Vaisheshika (IAST: Vaiśeṣika; ; ) is one of the six schools of Hindu philosophy from ancient India. In its early stages, the Vaiśeṣika was an independent philosophy with its own metaphysics, epistemology, logic, ethics, and soteriology. Over time, the Vaiśeṣika system became similar in its philosophical procedures, ethical conclusions and soteriology to the Nyāya school of Hinduism, but retained its difference in epistemology and metaphysics.
The epistemology of the Vaiśeṣika school of Hinduism, like Buddhism, accepted only two reliable means to knowledge: direct observation and inference. the Vaiśeṣika school and Buddhism both consider their respective scriptures as indisputable and valid means to knowledge, the difference being that the scriptures held to be a valid and reliable source by Vaiśeṣikas were the Vedas.
The Vaiśeṣika school is known for its insights in naturalism. It is a form of atomism in natural philosophy. It postulated that all objects in the physical universe are reducible to paramāṇu (atoms), and one's experiences are derived from the interplay of substance (a function of atoms, their number and their spatial arrangements), quality, activity, commonness, particularity and inherence. Everything was composed of atoms, qualities emerged from aggregates of atoms, but the aggregation and nature of these atoms was predetermined by cosmic forces. Ajivika metaphysics included a theory of atoms which was later adapted in the Vaiśeṣika school.
According to the Vaiśeṣika school, knowledge and liberation were achievable by a complete understanding of the world of experience.
Vaiśeṣika darshana was founded by Kaṇāda Kashyapa around the 6th to 2nd century BC.
Overview
Although the Vaiśeṣika system developed independently from the Nyāya philosphy of Hinduism, the two became similar and are often studied together. In its classical form, however, the Vaiśeṣika school differed from the Nyāya in one crucial respect: where Nyāya accepted four sources of valid knowledge, the Vaiśeṣika accepted only two.
The epistemology of Vaiśeṣika school of Hinduism accepted only two reliable means to knowledge – perception and inference.
Vaisheshika espouses a form of atomism, that the reality is composed of five substances (examples are earth, water, air, fire, and space). Each of these five are of two types, explains Ganeri: paramāṇu and composite. A paramāṇu is that which is indestructible, indivisible, and has a special kind of dimension, called “small” (aṇu). A composite is that which is divisible into paramāṇu. Whatever human beings perceive is composite, and even the smallest perceptible thing, namely, a fleck of dust, has parts, which are therefore invisible. The Vaiśeṣikas visualized the smallest composite thing as a “triad” (tryaṇuka) with three parts, each part with a “dyad” (dyaṇuka). Vaiśeṣikas believed that a dyad has two parts, each of which is an atom. Size, form, truths and everything that human beings experience as a whole is a function of parmanus, their number and their spatial arrangements.
Parama means "most distant, remotest, extreme, last" and aṇu means "atom, very small particle", hence paramāṇu is essentially "the most distant or last small (i.e. smallest) particle".
Vaiśeṣika postulated that what one experiences is derived from dravya (substance: a function of atoms, their number and their spatial arrangements), guna (quality), karma (activity), samanya (commonness), vishesha (particularity) and samavaya (inherence, inseparable connectedness of everything).
The followers of this philosophy are mostly Shaivas. Acharya Haribhadra Suri, in his work 'Ṣaḍdarśanasamuccaya' describes the followers of Vaiśeṣika as worshippers of Pashupati or Shiva.