Тілдегі мүмкіндік пен қажеттілік санаттары

Phenomenon whereby language is used to discuss possible situations
the closely related grammatical category

In linguistics and philosophy, modality refers to the ways language can express various relationships to reality or truth. For instance, a modal expression may convey that something is likely, desirable, or permissible. Quintessential modal expressions include modal auxiliaries such as "could", "should", or "must"; modal adverbs such as "possibly" or "necessarily"; and modal adjectives such as "conceivable" or "probable". However, modal components have been identified in the meanings of countless natural language expressions, including counterfactuals, propositional attitudes, evidentials, habituals, and generics. Modality has been intensely studied from a variety of perspectives. Within linguistics, typological studies have traced crosslinguistic variation in the strategies used to mark modality, with a particular focus on its interaction with tense–aspect–mood marking. Theoretical linguists have sought to analyze both the propositional content and discourse effects of modal expressions using formal tools derived from modal logic. Within philosophy, linguistic modality is often seen as a window into broader metaphysical notions of necessity and possibility.

Linguistic modality has been one of the central concerns in formal semantics and philosophical logic. Research in these fields has led to a variety of accounts of the propositional content and conventional discourse effects of modal expressions. The predominant approaches in these fields are based on modal logic. In these approaches, modal expressions such as must and can are analyzed as quantifiers over a set of possible worlds. In classical modal logic, this set is identified as the set of worlds accessible from the world of evaluation. Since the seminal work of Angelika Kratzer, formal semanticists have adopted a more finely grained notion of this set as determined by two conversational background functions called the modal base and ordering source respectively. For an epistemic modal like English must or might, this set is understood to contain exactly those worlds compatible with the knowledge that the speaker has in the actual world. Assume for example that the speaker of sentence (4) above knows that John just bought a new luxury car and has rented a huge apartment. The speaker also knows that John is an honest person with a humble family background and doesn't play the lottery. The set of accessible worlds is then the set of worlds in which all these propositions which the speaker knows about John are true. The notions of necessity and possibility are then defined along the following lines: A proposition P follows necessarily from the set of accessible worlds, if all accessible worlds are part of P (that is, if p is true in all of these worlds).

Complementizers (e. g. Russian) and conjunctions (e. g. Central Pomo) can be used to convey modality.