Linguistic modality

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In linguistics, modality is a feature of language that allows for communicating things about, or based on, situations which need not be actual. More precisely, modality is signalled by grammatical expressions (moods or auxiliary verbs) that express a speaker's general intentions (or illocutionary point) as well as the speaker's belief as to whether the proposition expressed is true, obligatory, desirable, or actual.

Linguistics is the scientific study of language. It involves analysing language form, language meaning, and language in context. The earliest activities in the documentation and description of language have been attributed to the 6th-century-BC Indian grammarian Pāṇini who wrote a formal description of the Sanskrit language in his Aṣṭādhyāyī.

In linguistics, grammatical mood is a grammatical feature of verbs, used for signaling modality. That is, it is the use of verbal inflections that allow speakers to express their attitude toward what they are saying. The term is also used more broadly to describe the syntactic expression of modality – that is, the use of verb phrases that do not involve inflection of the verb itself.

An auxiliary verb is a verb that adds functional or grammatical meaning to the clause in which it appears, such as to express tense, aspect, modality, voice, emphasis, etc. Auxiliary verbs usually accompany a main verb. The main verb provides the main semantic content of the clause. An example is the verb have in the sentence I have finished my lunch. Here, the main verb is finish, and the auxiliary have helps to express the perfect aspect. Some sentences contain a chain of two or more auxiliary verbs. Auxiliary verbs are also called helping verbs, helper verbs, or (verbal) auxiliaries.


Sometimes, the term mood is used to refer to both mood and modality; however, the two can be distinguished according to whether they refer to the grammatical expressions of various modalities (mood) or the meanings so expressed (modality). Modality can also be considered equivalent to the idea of illocutionary force if the kinds of expressions which can express modal meanings also include lexical items such as performative verbs.

Modality is closely intertwined with other linguistic phenomena such as tense and aspect, evidentiality, conditionals, and others. As with other areas of linguistics, modality has been studied extensively from typological as well as formal perspectives.

In grammar, tense is a category that expresses time reference with reference to the moment of speaking. Tenses are usually manifested by the use of specific forms of verbs, particularly in their conjugation patterns.

Aspect is a grammatical category that expresses how an action, event, or state, denoted by a verb, extends over time. Perfective aspect is used in referring to an event conceived as bounded and unitary, without reference to any flow of time during. Imperfective aspect is used for situations conceived as existing continuously or repetitively as time flows.

In linguistics, evidentiality is, broadly, the indication of the nature of evidence for a given statement; that is, whether evidence exists for the statement and if so, what kind. An evidential is the particular grammatical element that indicates evidentiality. Languages with only a single evidential have had terms such as mediative, médiatif, médiaphorique, and indirective used instead of evidential. Evidential is a meaning of nature and statement that is whether evidence exists for the statement and what kind of evidence exists.

Cross-linguistically, modality can be expressed by a variety of means, such as auxiliary verbs, verbal morphology (mood) or adverbs.

Typological approaches to modality usually favour a slightly wider definition of modality.

Linguistic typology is a field of linguistics that studies and classifies languages according to their structural and functional features. Its aim is to describe and explain the common properties and the structural diversity of the world's languages. Its subdisciplines include, but are not limited to: qualitative typology, which deals with the issue of comparing languages and within-language variance; quantitative typology, which deals with the distribution of structural patterns in the world’s languages; theoretical typology, which explains these distributions; syntactic typology, which deals with word order, word form, word grammar and word choice; and lexical typology, which deals with language vocabulary.

Epistemic and deontic modality

An important distinction within linguistic modality is the distinction between epistemic and deontic modality. Generally speaking, epistemic modality has to do with possibility and necessity with regard to knowledge, whereas deontic modality has to do with permission and obligation according to some system of rules. The difference between the two is illustrated in the English example below:

Epistemic modality is a sub-type of linguistic modality that deals with a speaker's evaluation/judgment of, degree of confidence in, or belief of the knowledge upon which a proposition is based. In other words, epistemic modality refers to the way speakers communicate their doubts, certainties, and guesses—their "modes of knowing". More technically, epistemic modality may be defined " an evaluation of the chances that a certain hypothetical state of affairs under consideration will occur, is occurring, or has occurred in a possible world which serves as the universe of interpretation for the evaluation process… In other words, epistemic modality concerns an estimation of the likelihood that a certain state of affairs is/has been/will be true in the context of the possible world under consideration. This estimation of likelihood is situated on a scale going from certainty that the state of affairs applies, via a neutral or agnostic stance towards its occurrence, to certainty that it does not apply, with intermediary positions on the positive and the negative sides of the scale".

Deontic modality is a linguistic modality that indicates how the world ought to be according to certain norms, expectations, speaker desire, etc. In other words, a deontic expression indicates that the state of the world does not meet some standard or ideal, whether that standard be social, personal (desires), etc. The sentence containing the deontic modal generally indicates some action that would change the world so that it becomes closer to the standard or ideal.

(1) Agatha must be the killer.
(2) Agatha must be killed.

The sentence in (1) might be spoken by someone who has decided that all of the relevant facts in a particular murder investigation point to the conclusion that Agatha is the killer, even though it may or may not actually be the case. In contrast, (2) might be spoken by someone who has decided that, according to some standard of conduct, Agatha has committed a vile crime, and therefore the correct course of action is to kill Agatha. Note also that, although English must is ambiguous between these two interpretations, the form of the other elements in the sentences helps to disambiguate.

In standard formal approaches to linguistic modality, an utterance expressing modality is one that can always roughly be paraphrased to fit the following template:

(1) According to [a set of rules, wishes, beliefs,...] it is [necessary, possible] that [the main proposition] is the case.

The set of propositions which forms the basis of evaluation is called the modal base. The result of the evaluation is called the modal force. For example the utterance in (2) expresses that, according to what the speaker has observed, it is necessary to conclude that John has a rather high income:

(2) John must be earning a lot of money.

The modal base here is the knowledge of the speaker, the modal force is necessity. By contrast, (3) could be paraphrased as ‘Given his abilities, the strength of his teeth, etc., it is possible for John to open a beer bottle with his teeth’. Here, the modal base is defined by a subset of John's abilities, the modal force is possibility.

(3) John can open a beer bottle with his teeth.

Semantic accounts

Semantic approaches dealing with modality are traditionally based on the principles of modal logic. Both work with the notion that propositions can be mapped to sets of possible worlds; that is, a proposition can be defined as the set of worlds in which that proposition is true. For example, the proposition ‘the earth is flat’ corresponds to the set of possible worlds in which the earth is in fact flat.

In this framework, modal expressions such as must and can are then analyzed as quantifiers over a set of possible worlds. This set of worlds is given by the modal base and is said to be the set of accessible worlds: For example, in sentence (2) above, the modal base is the knowledge the speaker has in the actual world. Therefore, the set of accessible worlds is defined by the information the speaker has about John. Assume for example that the speaker 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). Applied to the example in (2) this would mean that in all the worlds which are defined by the speaker's knowledge about John, it is the case that John earns a lot of money (assuming there is no other explanation for John's wealth).

In a similar way a proposition p is possible according to the set of accessible worlds (i.e. the modal base), if some of these worlds are part of p.

For further reading, see for example Kratzer 1991, Kaufmann et al. 2006 and Portner 2009.

Ways of expressing modality

Verbal morphology

In many languages modal categories are expressed by verbal morphology – that is, by alterations in the form of the verb. If these verbal markers of modality are obligatory in a language, they are called mood markers. Well-known examples of moods in some European languages are referred to as subjunctive, conditional and indicative as illustrated below with examples from French, all three with the verb avoir ‘to have’. As in most Standard European languages, the shape of the verb conveys not only information about modality, but also about other categories such as person and number of the subject.

`I doubt that you're right.'
`If this were true, one would have seen it on CNN.'
`He's right.'

An example for a non-European language with a similar encoding of modality is Manam. Here, a verb is prefixed by a morpheme which encodes number and person of the subject. These prefixes come in two versions, one realis version and one irrealis version. Which one is chosen depends on whether the verb refers to an actual past or present event (realis), or merely to a possible or imagined event (irrealis) (see Elliott 2000).


Modal auxiliary verbs, such as the English words may, can, must, ought, will, shall, need, dare, might, could, would, and should, are often used to express modality, especially in the Germanic languages.

Lexical expression

Verbs such as "want" can be used to express modality lexically, as can adverbs.


Complementizers (e.g. Russian) and conjunctions (e.g. Central Pomo, see Mithun 1995) can be used to convey modality.

Many different kinds of modal interpretations have been observed and studied, resulting in a variety of typologies. What follows below is one of the many ways that modality has been classified. Only broad categories have been distinguished below: the reader is referred to the main articles and the references for more detailed discussions.

Realis vs. irrealis

The closely related realis, declarative, and evidential moods refer to situations that actually exist, are claimed to exist, or are inferred to exist. In contrast, irrealis moods refer to situations that are known to not exist. Two common irrealis moods are the conditional mood, stating what would happen under a certain condition or conditions (expressed periphrastically in English as would + main verb), and the subjunctive mood, stating the speaker's preferences for what should occur (such as he leave in the English I demand that he leave) or hypotheticals (such as English If I were to go,....).

Counterfactuals refer to things that are contrary to the actual situation. In English, counterfactuals can be expressed implicitly in "if"-clauses by using a tense form that normally refers to a time prior to the time actually semantically referred to in the if-clause. For example, If I knew that, I wouldn't have to ask contains the counterfactual If I knew, which refers to the present tense despite the form of the verb, and which denies the proposition "I know that". This contrasts with the construction If I know that,..., which is not a counterfactual because it means that maybe I know it and maybe I don't (or maybe I will know it, and maybe I will not). Likewise, If I had known that, I would have gone there contains the counterfactual If I had known, denying the proposition that I had known.

Epistemic vs. deontic modality

Epistemic modals are used to indicate the possibility or necessity of some piece of knowledge. It deals with the likelihood of the actualization of the state of affairs. In the epistemic use, modals can be interpreted as indicating inference or some other process of reasoning involved in coming to the conclusion stated in the sentence containing the modal. However, epistemic modals do not necessarily require inference, reasoning, or evidence. One effect of using an epistemic modal (as opposed to not using one) is a general weakening of the speaker's commitment to the truth of the sentence containing the modal. However, it is disputed whether the function of modals is to indicate this weakening of commitment, or whether the weakening is a by-product of some other aspect of the modal's meaning.

Examples of the expression of epistemic modality in English are: he might be there (low probability, substantial doubt), He may be there (possibility), He should be there by now (high probability), and He must be there by now (certitude, no doubt).

In contrast, deontic modality is concerned with possibility and necessity in terms of freedom to act (including ability, permission, and duty). In other words, deontic modals state something about the desirability of the actualization of the state of affairs, expressed in varying degrees of obligation. English examples include She can go (ability), You may go (permission), You should go (request), and You must go (command). In English as in many other languages, some of the same words are used for deontic modality as for epistemic modality, and the meaning is distinguished from context: He must be there by now (epistemic) versus He must be there tomorrow at noon (deontic).

Ability, desirability, permission, obligation, and likelihood

Ability, desirability, permission, obligation, and probability can all be exemplified by the usage of auxiliary modal verbs in English:

Ability: I can ride a bicycle (in the present); I could ride a bicycle (in the past)
Desirability: I should go; I ought to go
Permission: I may go
Obligation: I must go
Likelihood: He might be there; He may be there; He must be there

See also

Related Research Articles

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Modal logic is a type of formal logic primarily developed in the 1960s that extends classical propositional and predicate logic to include operators expressing modality. A modal—a word that expresses a modality—qualifies a statement. For example, the statement "John is happy" might be qualified by saying that John is usually happy, in which case the term "usually" is functioning as a modal. The traditional alethic modalities, or modalities of truth, include possibility, necessity, and impossibility. Other modalities that have been formalized in modal logic include temporal modalities, or modalities of time, deontic modalities, epistemic modalities, or modalities of knowledge and doxastic modalities, or modalities of belief.

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English modal verbs Uninflected verbs in English

The modal verbs of English are a small class of auxiliary verbs used mostly to express modality. They can be distinguished from other verbs by their defectiveness and by the fact that they do not take the ending -(e)s in the third-person singular.

A modal verb is a type of verb that is used to indicate modality – that is: likelihood, ability, permission, request, capacity, suggestions, order and obligation, and advice etc. They always take base form of verb with them. Examples include the English verbs can/could, may/might, must, will/would and shall/should/ought to. In English and other Germanic languages, modal verbs are often distinguished as a class based on certain grammatical properties.

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