Maṇḍana’s thesis of iṣṭasādhanatā is an answer to the problem of how to identify the core of a prescription. What makes people undertake actions? Kumārila’s śabdabhāvanā (‘linguistic urge’) theory and Prabhākara’s kāryavāda (‘theory about duty [being the motivator]’) had already offered their answers.

Kumārila’s theory had two pillars:

• 1. a theory of rational behaviour being always goal-oriented,
• 2. a strong hermeneutic basis linked to the analysis of prescriptive language.

In the 2. analysis, exhortative verbal endings are analysed as entailing a verbal part (tiṅ) and an exhortative part (liṅ). The former express the action (bhāvanā), the latter express the injunction (vidhi/śabdabhāvanā). And any action needs three components, namely something to be brought about by the action (bhāvya), an instrument to bring it about (karaṇa) and a procedure (itikartavyatā), which is equated to the instrument’s instrument. bhāvanā, vidhi, bhāvya, karaṇa and itikartavyatā are all conveyed by the Vedic prescriptive sentence, but are they conveyed *qua* bhāvanā etc.? The answer is clearly affirmative for bhāvanā and vidhi, which are directly conveyed by tiṅ and liṅ respectively. By contrast, bhāvya, karaṇa and itikartavyatā might need the application of some further investigation on the part of the knower, who will need to apply hermeneutical rules (nyāya) to correctly interpret the sentence and link the bhāvya to the word mentioning the eligible person and the karaṇa to the meaning of the verbal root.

The first pillar (1) is taken up by Maṇḍana.
In fact, Maṇḍana expands on Kumārila’s intuition about human behaviour being always goal-oriented by offering a radical reductionist hypothesis. According to this hypothesis, being a motivator is nothing but communicating that the action to be undertaken is an instrument to some desired result. In this sense, prescribing X to people desiring Y is *nothing but* explaining that X is the means to achieve Y. The “nothing but” part of the definition is key to distinguish Maṇḍana’s position from Kumārila’s. Also for Kumārila a prescription presupposes that one understands that the prescribed action will lead to something independently desired.

Now, I am grateful to Sudipta Munsi, who recently made me read Uṃveka’s commentary on ŚV codanā 214, where Uṃveka rejects a view that seems a proto-version of Kumārila’s one, since it speaks of bhāvanā, of a desired bhāvya and of the meaning of the verbal root, but without mentioning the fact that this conveys the karaṇa. In this proto-Kumārila view, the prescriptive sentence impels (pravṛt-), but since one might doubt this impulsion, it implies (ākṣip-) a bhāvya in the form of something desirable and therefore orients the listener’s understanding to move past the meaning of the verbal root towards the identification of something really desirable. Uṃveka does not use the verb abhidhā- ‘directly denote’, but says that the prescriptive sentences conveys (avagam-) this meaning. The doubt (āśaṅkā) about the impulsion seems to be the reason for the implication (ākṣepa). Uṃveka does not frame this as a case of śrutārthāpatti (postulation of a linguistic element based on cogent evidence), because ākṣepa performs almost the same role (but without the postulation of an explicit linguistic unit, which remains implied).
Uṃveka contrasts to this view his own (vayaṃ tu brūmaḥ), according to which a prescriptive sentence first conveys an impulsion (preraṇā) and then (uttarakālam) conveys (pratī-) a desired goal. Here, there are important points that appear to be influenced by Maṇḍana (please remember that Uṃveka commented on Maṇḍana’s Bhāvanāviveka):

• The mention of the destruction of accumulated bad karman as the desired result for fixed sacrifices
• The connection between impulsion and the fact that the action impelled leads to a desirable goal

However, unlike in Maṇḍana, Uṃveka distinguishes impulsion (preraṇā) from the fact of being the instrument to a desired goal, whereas Maṇḍana’s main claim is that the two are completely identical. Uṃveka is possibly the first person mentioning the temporal sequence linking impulsion and the understanding (pratī-) of something as a desirable goal. Like in the discussion of the proto-Kumārila view, Uṃveka does not use the word abhidhā, but he says that the prescriptive content is conveyed (avagam-).

Pārthasārathi (another commentator of Kumārila) de facto embedded Maṇḍana’s view of iṣṭasādhanatā, i.e., the prescribed action is an instrument to a desired result, as part of Kumārila’s śabdabhāvanā theory, more precisely as its procedure (itikartavyatā).

This was just a quick summary. Specifications or corrections are welcome.