How do we gather knowledge through language? I can think of at least three possibilities:
- descriptive statements
- poetic language
In the first case, one comes to know that X through a linguistic expression provided that some basic presuppositions are fulfilled. Authors disagree as for them (see this post, this one and this one), but they would mostly agree that:
a) the hearer needs to be competent (i.e., that s/he must be in the condition to gather knowledge from a linguistic communication, e.g., insofar as s/he knows the relevant language, is not clinically mistrustful, etc.)
b) the speaker needs to be reliable, i.e. to be competent about what s/he is saying
c) the speaker needs to be sincere, i.e., s/he needs to want to tell the truth
d) the speaker needs to desire to communicate (this condition is usually considered as obvious in Western discussions about the epistemology of testimony, but it plays a role in Classical Indian epistemology of the Nyāya school)
b-c-d') X needs to be true (independently of the speaker)
b-c-d') leads to the additional problem of how to define truth, but since this does not regard only linguistic communication, I will leave it aside.
What happens, instead, in the case of 2. or 3.? As shown by Josif Bochenski, prescriptions depend on a deontic authority, not on an epistemic one. Thus, neither the competence nor the sincerity of the speaker are required. However, does the speaker need to be in an authoritative position in regard to the hearer, in order for the prescriptions to communicate knowledge? Yes and No. If I am a mother and I tell my son to go to bed, he will know that he is under the obligation to stop playing and put his pajama on. Other members of the audience will know that I told X to my son, but my prescription will not have communicated an obligation to them. They will not be under an obligation for having heard my prescription. In other words, unlike in the case of 1., the communicated obligation is personal and regards only a specific person (or class of people, e.g., a football team). In other words, in order for an obligation (as distinguished from the knowledge that X, where X might also be tantamount to the fact that someone else is under an obligation) to be communicated:
a'') the hearer needs to recognise the deontic authority of the prescription's source (note that I am avoiding speaker in order to make room for cases in which there is no personal speaker)
b'') the source needs to be a deontic authority for the hearer
The case 3. is also interesting. I would say that:
a''') The hearer needs a specific competence (Classical Indian authors call it sahṛdayatva 'ability to be sym-pathetic')
What is the specific content communicated in this case? Surely not knowledge, nor obligation. Perhaps a certain 'aesthetic experience` (e.g., the aesthetic experience of love, although one is not in love with Ophelia)?
Moreover, is something similar to a'') implied also by a)?