A modal verb (also modal, modal auxiliary verb, modal auxiliary) is a type of auxiliary verb that is used to indicate modality. The use of auxiliary verbs to express modality is a characteristic of Germanic languages.
Modal auxiliary verbs give more information about the function of the main verb that follows it. Although having a great variety of communicative functions, these functions can all be related to a scale ranging from possibility (can) to necessity (must). Within this scale there are two functional divisions:
must = absolute (often moral) obligation, order, requirement, necessity; can/could = physical or mental ability; may/might = permission, option, choice; will = intention in 1st person, volition in 2nd and 3rd persons; and shall/should = in 1st person objective though not moral obligation, no choice, as in: One day I shall die: we all shall die one day; in 2nd and third persons shall implies an incumbent obligation, destiny (It shall come to pass) or a command, decree, necessity imposed by the speaker, as in: A meeting shall take place on the last Friday of every month or a promise, namely that the speaker is stating his obligation to another party that an action or event take place, as in: You shall go to the ball, Cinderella. However, if a speaker states: I will let you go to the ball, Cinderella, in stating his intention, he is, in this instance, also making a promise.
Most modal auxiliary verbs have two distinct interpretations, epistemic (expressing how certain the factual status of the embedded proposition is) and deontic (involving notions of permission and obligation). The following sentences illustrate the two uses of must:
Another form of modal auxiliary is the verb indicating ability: "can" in English, "können" in German, and "possum" in Latin. For example, "I can say that in English," "Ich kann das auf Deutsch sagen," and "Illud Latine dicere possum."
Sometimes, the use of the modal auxiliary verbs varies in positive and negative statements. For example, in English, we have the sentence pair, "You may do that," and "You may not do that." However, in German, these ideas are expressed as "Sie dürfen das tun," but "Sie müssen das nicht tun." The latter looks as if it would translate into English as "You must not do that," but it is more typically translated as "You may not do that."
Words in the same row share the same etymological root. Because of semantic drift, however, words in the same row may no longer be proper translations of each other. In addition, the English and German verbs will are completely different in meaning, and the German one has nothing to do with constructing the future tense. These words are false friends.
In English, the plural and singular forms are identical. For German and Dutch, both the plural and singular form of the verb are shown.
Please note that the words in this list are not translations of each other. (See above.)
|can||können, kann||kunnen, kan|
|shall||sollen, soll||zullen, zal|
|will||wollen, will||willen, wil|
|must||müssen, muss||moeten, moet|
|may||mögen, mag||mogen, mag|
|tharf||dürfen, darf||durven, durf|
The English could is the past tense of can; should is the past tense of shall; and might is the past tense of may. (This is ignoring the use of "may" as a vestige of the subjunctive mood in English.) These verbs have acquired an independent, present tense meaning. The German verb möchten is sometimes taught as a vocabulary word and included in the list of modal verbs, but it is actually the past subjunctive form of mögen. An example of the subjective use of "may" in English is in the sentence "That may be, or may not be," meaning "That could be true, but maybe it is not."
The English verbs dare and need have both a modal use (he dare not do it), and a non-modal use (he doesn't dare to do it). The Dutch verb durven is not considered a modal (but it is there, nevertheless) because its modal use has disappeared, but it has a non-modal use analogous with the English dare. Other English modal verbs include want, wish, hope, and like. All of these differ from the main modals in English (i.e. most of those in the table above) in that they take the particle to in the infinitive, like all other English verbs (may; to want), and are followed by to when they are used as a modal (may go; want to go). Some may be more than one word, such as "had better" and "would rather."
Germanic modal verbs are preterite-present verbs, which means that their present tense has the form of a vocalic preterite. This is the source of the vowel alternation between singular and plural in German and Dutch. Because of their preterite origins, modal verbs also lack the suffix (-s in modern English, -t in German and Dutch) that would normally mark the third person singular form:
|normal verb||modal verb|
|English||he works||he can|
|German||er arbeitet||er kann|
|Dutch||hij werkt||hij kan|
The main verb that is modified by the modal verb is in the infinitive form and is not preceded by the word to (German: zu, Dutch: te). There are verbs that may seem somewhat similar in meaning to modal verbs (e.g. like, want), but the construction with such verbs would be different:
|normal verb||modal verb|
|English||he tries to work||he can work|
|German||er versucht zu arbeiten||er kann arbeiten|
|Dutch||hij probeert te werken||hij kan werken|
In English, main verbs but not modal verbs always require the auxiliary verb do to form negations and questions, and can be used to form emphatic affirmative statements. Neither negations nor questions in early modern English used to require do.
|normal verb||modal verb|
|affirmative||he works||he can work|
|negation||he does not work||he cannot work|
|emphatic||he does work hard||he can work hard|
|question||does he work here?||can he work at all?|
|negation + question||does he not work here?||can he not work at all?|
(German never uses "do" as an auxiliary verb for any function; Dutch uses "do" as an auxiliary, but only in colloquial speech)
Modal verbs are called defective verbs because of their incomplete conjugation: they have a narrower range of functions than ordinary verbs.