Apurva in Mimamsa philosophy is the performative element of an injunction that justifies ritualistic acts and their results.
Originally Apurva had to do with the all too common religious beliefs according to which a reward is given to anyone who strictly adheres to religious obligations and that made Apurva an intervening agency to be presented by the Mimamsa school as a theological tool for solving the discrepancy that may arise between the ritualistic act and its result i.e. an epistemic mechanism that indicates knowledge of casual links between acts and their consequences.
Wilhelm Halbfass [4] understands it to be, within well-defined conditions, a conceptual device that is assumed to operate within a kind of closed system in which it seems to be secure against outside interference, that it serves as a mediator, as a conceptual link between the drsta (the visible) and the adrsta (invisible) connecting the empirical spheres of actions and reactions with the religious non-empirical sphere in which lie the values of these actions and reactions.
[8] Adi Shankara rejects the notion that the statement Atmetyevopasita is the primary injunction, Apurva Vidhi, to meditate on Brahman as one’s own Self because Self-knowledge is not an action that can be enjoined.
[9] The Later Advaita thinkers, such as Madhusudana, held the view that just like Apurva as a subtle state continues to linger after the sacrifice is over, ignorance remains in the subtle state of avidya even after the dawn of knowledge, and as there is an interval between cause and effect similarly there is an interval between knowledge and body-fall.