These six things are called the six padârthas or independent realities experienced in perception and expressed in language.
The Theory of Causation.
The Nyâya-Vais'e@sika in most of its speculations took that view of things which finds expression in our language, and which we tacitly assume as true in all our ordinary experience. Thus
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[Footnote 1: The Vedânta does not admit the existence of the relation of samavâya as subsisting between two different entities (e.g. substance and qualities). Thus S'a@nkara says (Brahma-sûtrabhâ@sya II. ii. 13) that if a samavâya relation is to be admitted to connect two different things, then another samavâya would be necessary to connect it with either of the two entities that it intended to connect, and that another, and so there will be a vicious infinite (anavasthâ). Nyâya, however, would not regard it as vicious at all. It is well to remember that the Indian systems acknowledge two kinds of anavasthâ—prâmâ@nikî (valid infinite, as in case of the question of the seed and the tree, or of the avidyâ and the passions), and another aprâmâ@nikî anavasthâ (vicious infinite) as when the admission of anything invokes an infinite chain before it can be completed.]
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they admitted dravya, gu@na, karma and sâmânya, Vis'e@sa they had to admit as the ultimate peculiarities of atoms, for they did not admit that things were continually changing their qualities, and that everything could be produced out of everything by a change of the collocation or arrangement of the constituting atoms. In the production of the effect too they did not admit that the effect was potentially pre-existent in the cause. They held that the material cause (e.g. clay) had some power within it, and the accessory and other instrumental causes (such as the stick, the wheel etc.) had other powers; the collocation of these two destroyed the cause, and produced the effect which was not existent before but was newly produced. This is what is called the doctrine of asatkâryavâda. This is just the opposite of the Sâ@mkhya axiom, that what is existent cannot be destroyed nâbhâvo vidyate sata@h) and that the non-existent could never be produced (nâsato vidyate bhâvah). The objection to this view is that if what is non-existent is produced, then even such impossible things as the hare's horn could also be produced. The Nyâya-Vais'e@sika answer is that the view is not that anything that is non-existent can be produced, but that which is produced was non-existent [Footnote ref 1].
It is held by Mîmâ@msâ that an unseen power resides in the cause which produces the effect. To this Nyâya objects that this is neither a matter of observation nor of legitimate hypothesis, for there is no reason to suppose that there is any transcendental operation in causal movement as this can be satisfactorily explained by molecular movement (parispanda). There is nothing except the invariable time relation (antecedence and sequence) between the cause and the effect, but the mere invariableness of an antecedent does not suffice to make it the cause of what succeeds; it must be an unconditional antecedent as well (anyathâsiddhis'ûnyasya niyatâpûrvavarttitâ). Unconditionality and invariability are indispensable for kâryakâra@na-bhâva or cause and effect relation. For example, the non-essential or adventitious accompaniments of an invariable antecedent may also be invariable antecedents; but they are not unconditional, only collateral or indirect. In other words their antecedence is conditional upon something else (na svâtantrye@na). The potter's stick is an unconditional invariable antecedent of the jar; but the colour
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[Footnote 1: Nyâyamuñjari, p. 494.]