Overlapping interpretations of modalities (possibility)
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 the availability of epistemic interpretations for situational possibility.2 Such interpretations may be possible or not, be available for every strategy used to express situational possibility or only some of them, and they can also overlap partially. In case of full overlap every strategy for situational possibility 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:
NoSitPsbl: Possibility cannot be expressed through verbal modality.4
SitPsbl=Ep: There is no distinction between situational and epistemic possibility in the language.5
SitPsblPartEp: Only a part of the strategies used for expressing situational possibility has an epistemic interpretation in the language.6
SitPsbl~Ep: The strategies used for situational possibility overlap only partially regarding situational and epistemic interpretations.7
SitPsblNonEp: None of the strategies used to express situational possibility 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 SitPsbl=Ep and SitPsblNonEp do not combine with anything.
1: Situational possibility refers to a situation in which an agent is either capable of an action, allowed to perform it, or faces no objective obstruction from performing it. Examples include The boy can drive a car/understand this/get this book. Epistemic possibility, on the other hand, refers to a possibility based on the speaker’s opinion, such as The boy may be home by now.
2: This parameter can be studied only after the values for the Situational possibility 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 possible that..., It is imaginable 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 possibility parameter of the language only in case it has no other (grammaticalised) strategies to express possibility (that is, none of the other parameter values apply).
5: That is, all the strategies listed under the Situational possibility parameter can have an epistemic interpretation without any change.
6: In this case all the strategies listed under the Situational possibility 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.