I and other people are making a collaborative conlang. It features mood/evidentiality contrast. There are 4 moods:
There are also 6 evidentials:
The problem is we disagreed whether Imperative/Optative/Conditional (i.e. Irrealis moods) are compatible with evidentials. I feel they are incompatible, but the other conlangers think they are.
The most prototypical evidentials are a class of verbal affixes. They are not commonly tenses or moods of their own (though they can be). As such, they are not structurally incompatible with the irrealis/conditional, and ultimately it really depends on what exactly that mood is being used for by a language.
In Quechua, counterfactuals (If I had hooves, I'd be a horse) use the irrealis marker -man, but cannot (as I understand it anyway) take evidentials, but a statement of probability (She may be at school), which also uses the same marker, definitely can.
Irrealis statements about future events or hypotheticals, on the other, can also reasonably be said to be semantically unsuitable to use evidentials: in I will try to feed her some soup, the "feed her some soup" subclause is not really a statement you can really describe the source of the information (unless you have a dedicated evidential for that case, but natural languages don't). Nonetheless, WALS notes that some languages do:
Because evidentials are used to describe the speaker’s involvement with events, they tend to occur in realis contexts, especially in past tense situations. Nevertheless, evidentials do occur in what can be described as irrealis situations. Example (9) from Barasano (Eastern Tucanoan; Colombia; Jones and Jones 1991: 116) shows an interrogative evidential, and (10), from Tsova-Tush (Nakh-Daghestanian; Georgia; Holisky and Gagua 1994: 180) shows an evidential with a future event.
Remember that "grammar is born hungry" (attr. to W. Annis). While evidentials probably won't mix with the conditional mood in an additive fashion, they may produce other non-combinatorial meanings. So ("if" + conditional + direct) might be a normal condition, while ("if" + conditional + hearsay) might end up meaning that the scenario is especially unlikely, and ("if" + conditional + inferential) could indicate that the scenario would be bad.
Similarly, evidentials could be added to imperatives more directly to indicate the knowledge on which the command is based. (imperative + inferential) could be a normal imperative, while (imperative + direct) implies authority and (imperative + hearsay) indicates that you're passing down a command from your superior.
Wikipedia mentions that the same particles that indicate evidentiality are not infrequently also used to indicate mirativity, modality, tense, or aspect, though it doesn't give any examples, so take that with a grain of salt.
Of course it's also absolutely possible (or even probable) that certain combinations of modality and evidentiality are simply disallowed in your language. I would be very surprised if all 32 potential combinations of modality and evidentiality in your language were permitted (for example, a gnomic optative seems pretty contradictory to me).
I think it could be argued that some of your evidentials may be compatible with some of your moods.
Expressing something hoped hoped for or wished for (optative) seems it might pair nicely with the dubitative marker, perhaps expressing unlikelihood. It would also pair naturally with the direct marker, as, obviously, the speaker has direct knowledge of that which she hopes for!
Conditional seems to be compatible with hearsay, gnomic, and perhaps inferential markers.
Imperative, I think, subsumes direct evidentiality to the exclusion of the others. It would be a pretty poor general who commands his men "Charge-I think, maybe?"
I think it could also be argued that evidential marking of those other moods would be redundant, because obviously the source of information regarding a command is the one who issues the command! Perhaps evidential marking in those instances could be put to other uses?
