In its early stages, Vaiśeṣika was an independent philosophy with its own metaphysics, epistemology, logic, ethics, and soteriology.
[1] 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.
[2][3] The epistemology of Vaiśeṣika school of Hinduism accepted only two reliable means to knowledge – perception and inference.
[2] Vaisheshika espouses a form of atomism, that the reality is composed of five substances (examples are earth, water, air, fire, and space).
Whatever human beings perceive is composite, and even the smallest perceptible thing, namely, a fleck of dust, has parts, which are therefore invisible.
Size, form, truths and everything that human beings experience as a whole is a function of parmanus, their number and their spatial arrangements.
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).
All objects of experience can be classified into six categories, dravya (substance), guṇa (quality), karma (activity), sāmānya (generality), viśeṣa (particularity) and samavāya (inherence).
[28] Six pramāṇas (epistemically reliable means to accurate knowledge and to truths)[29] are noted within different Indian philsophical schools: Pratyakṣa (perception), Anumāna (inference), Śabda or āgama "(word, testimony of past or present reliable experts), Upamāna (comparison and analogy), Arthāpatti (postulation, derivation from circumstances), and Anupalabdhi (non-perception, negative/cognitive proof).
[2][3][30] Of these Vaiśeṣika epistemology considered only pratyakṣa (perception) and anumāna (inference) as reliable means of valid knowledge.