alethic modality

Linguistic modality

In linguistics, modals are expressions broadly associated with notions of possibility and necessity. Modals have a wide variety of interpretations which depend not only upon the particular modal used, but also upon where the modal occurs in a sentence, the meaning of the sentence independent of the modal, the conversational context, and a variety of other factors. For example, the interpretation of an English sentence containing the modal 'must' can be that of a statement of inference or knowledge (roughly, epistemic) or a statement of how something ought to be (roughly, deontic). The following pair of examples illustrate the interpretative difference:

(1) John didn't show up for work. He must be sick.
(2) John didn't show up for work. He must be fired.

The use of 'must' in (1) is interpreted as indicating a statement of reasoned conclusion: the speaker concludes John is sick, because otherwise John would have shown up for work. In contrast, in (2), 'must' is interpreted as a statement of how something ought to be: the speaker is saying that, because John didn't show up for work, John ought to be fired.

The use of a modal, particularly in cases like example (1) above, contrasts subtly with not using a modal, as illustrated below:

(3) John must be sick.
(4) John is sick.

The use of the modal in (3) is interpreted as indicating that some process of reasoning was used to arrive at the conclusion that John is sick. The lack of the modal in (4) tends to preclude such an interpretation, and is generally considered to be a statement of fact (i.e., the speaker knows that John is sick). In other words, a speaker would typically not say (3) if the speaker knows that (4) is true.


Modality is expressed in different ways by different languages. Modality can be expressed via grammaticized elements such as auxiliary verbs or verb endings, via indirect means such as a preposition phrase or a clause, or in other ways, such as via adverbs. For example, in English, the two sentences below have roughly the same meaning, but express the meaning in two different forms:

(5) It is possible that the Moon is made of cheese.
(6) The Moon might be made of cheese.

Subtle, and sometimes not-so-subtle, differences in interpretation occur depending on the way modality is expressed. Certain forms of expression may highlight certain aspects of modal meaning. Many languages will mark some modalities with particular word endings, etc., but will leave other means for marking other modalities (e.g. phrases).

Traditionally, studies of modality distinguish between:


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 references for more detailed discussions.


Epistemic modals are used to indicate the possibility or necessity of some piece of knowledge. 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.


Deontic modals are those that indicate how the world ought to be, according to certain norms, expectations, speaker desire, etc. In other words, deontic uses indicate that the state of the world (where 'world' is loosely defined here in terms of the circumstances surrounding the use of the modal) does not meet some standard or ideal, whether that standard be social (such as laws), 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/ideal.

Propositional attitudes

When considering modality it is useful to distinguish between two parts:

  • The dictum: what is said
  • The modus: how it is said, i.e. the speaker's propositional attitude toward what is said, e.g. the speaker's cognitive, emotive, and/or volitive attitude.

Consider the following English sentence:

It is hot outside.

This dictum could be paired with various types of modi, such as the following:

I think that it is hot outside.
I believe that it is hot outside.
I know that it is hot outside.
I hope that it is hot outside.
I doubt that it is hot outside.
It must be hot outside.
It has to be hot outside.
It might be hot outside.
It could be hot outside.
It needn't be hot outside.
It shouldn't be hot outside.
It is probably hot outside.
Perhaps it is hot outside.
It is possible that it is hot outside.
It is certain that it is hot outside.
It is probable that it is hot outside.
It is likely that it is hot outside.

Possible worlds

One approach to studying modal expressions has been through the use of a possible worlds theory.

Roughly, possible worlds accounts of modals generally claim that modals indicate the existence of possible worlds where the sentence containing the modal (minus the modal itself) is true, although this is a broad characterization.

Epistemic modality & evidentiality

Epistemic modality appears to have a close relationship with evidentiality, due to some characteristics which expressions of both types have in common. However, it is not certain what the nature of the relationship is. The crux of the debate is, essentially, this question: Is evidentiality a kind of epistemic modality, or are evidentiality and epistemic modality distinct, only sharing (more or less) some common characteristics?

See also

External links

SIL: ("what is...?")


  • Blakemore, D. (1994). Evidence and modality. In R. E. Asher (Ed.), The Encyclopedia of language and linguistics (pp. 1183-1186). Oxford: Pergamon Press. ISBN 0-08-035943-4.
  • Bybee, Joan; & Fleischman, Suzanne (Eds.) (1995). Modality in grammar and discourse. Amsterdam: John Benjamins.
  • Bybee, Joan; Perkins, Revere, & Pagliuca, William (1994). The evolution of grammar: Tense, aspect, and modality in the languages of the world. Chicago: University of Chicago Press.
  • Calbert, J. P. (1975). Toward the semantics of modality. In J. P. Calbert & H. Vater (Eds.), Aspekte der Modalität. Tübingen: Gunter Narr.
  • Chung, Sandra; & Timberlake, Alan (1985). Tense, aspect and mood. In T. Shopen (Ed.), Language typology and syntactic description: Grammatical categories and the lexicon (Vol. 3, pp. 202-258). Cambridge: Cambridge University Press.
  • Kiefer, Ferenc (1986). Epistemic possibility and focus. In W. Abraham & S. de Meij (Eds.), Topic, focus, and configurationality. Amsterdam: Benjamins.
  • Kiefer, Ferenc (1994). Modality. In R. E. Asher (Ed.), The Encyclopedia of language and linguistics (pp. 2515-2520). Oxford: Pergamon Press. ISBN 0-08-035943-4.
  • Kratzer, A. (1981). The notional category of modality. In H.-J. Eikmeyer & H. Rieser (Eds.), Words, worlds, and contexts: New approaches in word semantics. Berlin: Walter de Gruyter.
  • Palmer, F. R. (1979). Modality and the English modals. London: Longman.
  • Palmer, F. R. (1986). Mood and modality. Cambridge: Cambridge University Press. ISBN 0-521-26516-9, ISBN 0-521-31930-7. (2nd ed. published 2001).
  • Palmer, F. R. (2001). Mood and modality (2nd ed.). Cambridge: Cambridge University Press. ISBN 0-521-80035-8, ISBN 0-521-80479-5.
  • Palmer, F. R. (1994). Mood and modality. In R. E. Asher (Ed.), The Encyclopedia of language and linguistics (pp. 2535-2540). Oxford: Pergamon Press.
  • Saeed, John I. (2003). Sentence semantics 1: Situations: Modality and evidentiality. In J. I Saeed, Semantics (2nd. ed) (Sec. 5.3, pp. 135-143). Malden, MA: Blackwell Publishing. ISBN 0-631-22692-3, ISBN 0-631-22693-1.
  • Sweetser, E. E. (1982). Root and epistemic modality: Causality in two worlds. Berkeley Linguistic Papers, 8, 484-507.

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