The following is Jayanta Bhaṭṭa’s definition of an exhortative force:
The linguistic force is that activity pertaining to language which causes people to undertake actions and in which the undertaking of the activity is understood as something to be done.
(yas tu śabdagataḥ prayojakavyāpāro yatra puruṣapravṛttiḥ sādhyatāṃ pratipadyate sā śabdabhāvanā (GS edition p. 67; Mysore p. 97)).
The chief elements of this definitions are that the exhortative force is a function (vyāpara), related to language (śabdagata) and inherently prescriptive (sādhyatāṃ pratipadyate).
This leads us back to the question mentioned in yesterday's post, namely "To whom does the illocutionary force belong?" In Jayanta's terminology, this can be specified as "How can the burden of expressing the illocutionary force rest on a function?"
Jayanta addresses the problem insofar as he investigates on the relation between exhortation and prescriptive verbal endings? Do prescriptive verbal endings directly express exhortation, or is it their functioning (vyāpāra), which induces one to act? If the former, then everyone would undertake an activity, just by hearing an exhortative verbal ending, even one who does not know Sanskrit. If the latter, then one needs the intermediate step of understanding them, since the functioning of the prescriptive verbal ending consists in their conveying a meaning.
Hence, the burden of the illocutionary force is carried by both language and its listeners. Further, language is a vehicle of illocutionary force not in itself, as if it had a magical power, but rather insofar as it conveys a meaning. In other words, the illocutionary force is rooted in the epistemological aspect of language.