An introductory text may be found in Sprechakt, Satztyp, Modalität.

Modality is a functional domain comprising a set of sentence-level concepts and operations which specify the relation of the coded situation to reality.

Levels of modality

The most important subdivision of modality is according to the exact nature of the two relata of the modal relation. The entity that is the source of the modality may or may not be part of the situation coded by the sentence. If that entity is a participant of the situation, modality expresses that the reality of the situation somehow depends on that participant. If the source of the modality is not part of the situation coded, then it is typically – although not necessarily – the speaker; and the other relatum of the modal relation is not the situation coded, but rather the proposition.

• If modality is a relation between an external entity and the proposition, it is subjective modality.
• If modality is a relation between the referent of the sentence subject and the predicate, it is objective modality.

The distinction may be ilustrated as follows:

E1. Linda must be in the bathroom.
E2. Linda must go to the bathroom.

The most straightforward interpretation of E1 is that the speaker infers, from some evidence or deductive basis, that 'Linda is in the bathroom' is real. That is an example of subjective modality. The most straightforward interpretation of E2 is that there is some physical condition in Linda that makes 'Linda goes to the bathroom' necessary. That is an example of objective modality.

Objective modality is called this because it is grounded in the nature of things, esp. the entities taking part in the situation designated. Subjective modality is called that because it typically depends on the speaker, or else on some other entity that has a subjective attitude towards the proposition.

Observe that the terms are somewhat misleading in two respects:

• In a sense, all modality is subjective, since the modalization is necessarily due to some origo (source).
• That modality that is grounded in the sentence-subject is not called subjective, but objective.

• Subjective modality is also called propositional modality.
• Objective modality is also called dynamic modality.

Logically, a three-level distinction could be assumed (cf. Hengeveld 2004):

However, such a threefold distinction is only appropriate for possibility. It is not possible for volition, since the wishes of unidentified entities play no role in linguistic structure. And it is not possible for necessity, since the imposition of a necessity by the speaker is merged with the imposition of a necessity by an unidentified entity.

Consequently, it suffices to distinguish between subjective and objective modality as before.

In a semasiological perspective, the two levels of modality are related by synchronic and diachronic variation, as already shown by E1f. In an onomasiological perspective, subjective and objective modality have little to do with each other. In particular, subjective modality is intimately related with other functional domains such as illocution and deixis, which have nothing to do with objective modality. On the other hand, the principal modal relations holding at the two levels are essentially analogous, as shown in the table below.

Modal relations

At either of the two levels, specific modal relations are distinguished as follows:

Illocution vs. modality