Vaisheshika, also Vaisesika, (Sanskrit: वैशॆषिक)is one of the six Hindu schools of philosophy (orthodox Vedic systems) of India. Historically, it has been closely associated with the Hindu school of logic, Nyaya.
Vaisesika espouses a form of atomism and postulates that all objects in the physical universe are reducible to a finite number of atoms. Originally proposed by the sage Kanāda (or Kana-bhuk, literally, atom-eater) in the 2nd-3rd centuries CE (?). .
Although the Vaishesika system developed independently from the Nyaya, the two eventually merged because of their closely related metaphysical theories. In its classical form, however, the Vaishesika school differed from the Nyaya in one crucial respect: where Nyaya accepted four sources of valid knowledge, the Vaishesika accepted only perception and inference. Vaishesika atomism also differs from the atomic theory of modern science: according to the Vaishesikas, the functioning of atoms was guided or directed by the will of the Supreme Being. This is therefore a theistic form of atomism.
An alternative view would qualify the above in that the holism evident in the ancient texts mandate the identification of six separate traditional environments of philosophy, consisting of three sets of two pairs.
The logic of Vaisheshika
Being associated with the school of logic, early Vaisesika texts use a sneaky but clever logical argument to prove that the world is made of indivisible atoms: Assume that the world is not made of indivisible atoms, and that matter is continuous. Take a stone. One can divide this up into infinitely many pieces (since matter is continuous). Now, the Himalayan mountain range also has infinitely many pieces, so one may build another Himalayan mountain range with the infinite number of pieces that one has. One begins with a stone and ends up with the Himalayas, which is obviously ridiculous - so the original assumption that matter is continuous must be wrong, and so all objects must be made up of a finite number of pieces, called atoms.
Later Vaisesika philosophers tried to develop a theory to explain the properties of materials as the interaction of different types of atoms that make up the material. However, Vaisesika philosphy states that these interactions are driven by divine will, making this school of philosophy a theistic one.
Epistemologically, the Vaisesika school accepts perception (pratyaksha) and inference (anumāna) as valid sources of knowledge.
Later Vaisesika commentators include Prasastapada and Sridhara. Over the centuries, the school merged with the Nyaya system of Indian philosophy to form the combined school of Nyaya-Vaisesika. The school suffered a natural decline in India after the 15th century.
- Max Muller on the Vaisesika school (http://www.philo.demon.co.uk/vaishesh.htm)