Modality markers are linguistic elements encoding the attitude of the signer toward the validity of the content of a proposition, or the necessity/permission of an event to happen. To be more specific, we usually distinguish between markers of deontic modality and markers of epistemic modality. Deontic modality is the semantic category conveying obligation, necessity, recommendation, ability, permission and intention/volition. On the other hand, epistemic modality carries the judgment of the signer with respect to the truth of the utterance and to the probability of the event, based on his/her knowledge or evidences. In other words, epistemic markers yield the signer’s estimation of the likelihood of an event or state. The circumstances influencing the event can either be internal or external to the participant(s).
Sign languages can select various markers to encode modality, either lexical, such as manual signs, or morphosyntactic, such as non-manual markers occurring with modal verbs or morphological modifications of the articulation of the verb.
In LIS, we find lexical markers, i.e. manual signs, dedicated to each modality. We describe them in turn. For the morphological features and syntactic distribution of modality markers, the reader is referred to MORPHOLOGY 3.4 and SYNTAX 2.3.1.3, respectively.