Overlapping interpretations of modalities (necessity)
Linguistic modality includes necessity and possibility, each with a situational (Sit) and an epistemic (Ep) variant. Situational modality indicates that the described information is based on objective circumstances, while epistemic modality refers to the speaker’s opinions.1
Languages vary according to the possibility of using the same strategies to express situational and epistemic modality. In this parameter we are concerned with availability of epistemic interpretations for situational necessity.2 Such interpretations may be possible or not, be available for every strategy used to express situational necessity or only some of them, and they can also overlap partially. In case of full overlap every strategy for situational necessity has an epistemic reading as well. In the case of specific overlap it is true only for a subset of the strategies. Partial overlap refers to the use of identical lexical or grammatical strategies3 with distinctions in morphology (e.g. in conjugation/declination) or word order.
Types:
NoSitNec: Necessity cannot be expressed through verbal modality.4
SitNec=Ep: There is no distinction between situational and epistemic necessity in the language.5
SitNecPartEp: Only a part of the strategies used to express situational necessity has an epistemic interpretation in the language.6
SitNec~Ep: The strategies used for situational necessity overlap only partially regarding situational and epistemic interpretations.7
SitNecNonEp: None of the strategies used to express situational necessity can have an epistemic interpretation in the language.
When a language displays more than one type, two values can be listed. If one type is dominant, appearing in a greater variety of environments, a slash (/) can separate the two values, with the dominant value appearing first; if neither is dominant, they are listed with an ampersand (&) separating the two. Needless to say, the parameter values SitNec=Ep and SitNecNonEp do not combine with anything.
1: Situational necessity refers to an objective need, such as War requires weapons, Everyone must die one day and A master’s degree is a prerequisite for application to the program. Epistemic necessity, on the other hand, refers to a need or requirement based on the speaker’s opinion, such as The boy must be home by now.
2: This parameter can be studied only after the values for the Situational necessity parameter have been established for the language, which must serve as the basis for the parameter values identified here.
3: This may refer to the same auxiliary or the same affix, for example.
4: This value applies to the expression of modality in a main clause containing a subordinate clause, as seen in examples such as It’s necessary that..., It is unquestionable that... Such constructions do not constitute verbal modality, but rather logical modality, which is not addressed in this parameter. For this reason we attributed this parameter value to the Situational necessity parameter of the language only in case it has no other (grammaticalised) strategies to express necessity (that is, none of the other parameter values apply).
5: That is, all the strategies listed under the Situational necessity parameter can have an epistemic interpretation without any change.
6: In this case all the strategies listed under the Situational necessity parameter have to be considered one by one.
7: For a definition of partial overlap see the introductory paragraphs here. The details should be discussed and illustrated with examples in the commentary section.