German/Grammar/Modal auxiliary verbs

Modal auxiliary verbs
In this section we'll cover verbs which combine with the infinitive of other verbs to create a new meaning. We've seen one of these already, werden, which combines with an infinitive to form the future tense.

Terminology
We introduced auxiliary verbs in the section on the future tense. In addition to forming new tenses, an auxiliary verb can change the meaning in some other way. There are other special forms of verbs which can be used with auxiliary verbs, for example the verb "to have" combines with the special form "seen" of the verb "to see" to form the perfect tense, a type of past tense: "He has seen." (In this case the special form is called the past participle and we'll be covering the German version in more detail later.) In this section we'll be covering only those verbs which combine with the infinitive of another verb.

A modal verb is an auxiliary verb that changes the modality of a sentence. Modality is used to indicate possibility or desire rather than actual fact. For example "He sees a dog," expresses a simple fact, but "He can see a dog," expresses a possibility; he might not see the dog at the moment but he can if he wants to. In both German and English, modality is usually expressed by combining an auxiliary verb with the infinitive of the main verb.

There are some verbs that might be called auxiliary because they combine with another verbs, but they don't form a new tense or change the modality. English, in most cases, requires the verbs to be connected with a "to": It's also possible that verb can combined with the gerund, formed in English by adding "-ing", of another verb: These are handled differently in German and we'll be covering them in other sections.
 * "We decided to buy."
 * "We don't encourage smoking."

The sentence structure with a modal verb is the same as with werden and the future tense. As an example we'll use dürfen, which is similar to "may"; in the first person singular it's darf. Compare: In both, the auxiliary verb is conjugated and placed where the finite verb should go, in this case the first position because it's a polar question. And in both cases the main verb is changed to the infinitive and moved to the end of the clause.
 * Werde ich dich küssen? – "Will I kiss you?"
 * Darf ich dich küssen? – "May I kiss you?"

The six modal verbs in German are dürfen, können, mögen, müssen, sollen and wollen. This is almost the same list as the past-like present verbs we covered in the section on irregular verbs. The verb "wissen" is absent because it can't be used as a modal verb. Of the rest, we've only covered mögen and wollen in detail there because they have non-modal meanings. We'll also cover lassen here because it's "modal-like", an edge case that should have special treatment.

dürfen
You use dürfen for permission or to be allowed to do something. It's usual translation is "may". It follows the past-like present conjugation pattern with a vowel change from ü to a in the singular of the present tense. Examples:
 * Darf ich dich küssen? – "May I kiss you?"
 * Wir dürfen die Kekse essen. – "We may eat the cookies."

können
You use können to express the ability to do something, much like its English cognate "can". It follows the past-like present conjugation pattern with a vowel change from ö to a in the singular of the present tense. Examples:
 * Er kann einen Hund sehen. – "He can see a dog."
 * Wir können in die USA fliegen. – "We can fly to the US."

As with the English "can", können is sometimes used informally to express permission rather than ability.

mögen
Recall that mögen as a transitive verb means to like or enjoy something. But when combined with an infinitive it expresses a possibility. This sense is similar to its English cognate "may", though "might" is often a better translation. Confusingly, mögen is not used for permission as "may" is in English; for permission use dürfen. There is a great deal of overlap in meaning between mögen and können here; können is usually preferred and it's unusual to use mögen in this sense. We'll see that mögen gets more use in the subjunctive, but that will be covered in another section. Example:
 * Es mag so sein. – "It might be so."

müssen
This is a cognate to the English "must" and usually has about the same meaning, expressing a need or obligation to do something. It's often better to translate this as "have to"; see the section on negation below. It follows the past-like present conjugation pattern with a vowel change from ü to u in the singular of the present tense. Examples:
 * Ich muss gehen. – "I have to go."
 * Wir müssen hier bleiben.  – "We must stay here."

sollen
This is cognate to both "shall" and "should" in English, but the meaning is closer to "should". This could be a question of morality or it can be a recommended action. It can also mean that something is intended or supposed to happen; in this sense it's a kind of imperative. It can only mean "shall" in the biblical sense, as in "Thou shalt not steal." With such a variety of possibilities, you need to pay attention to context to understand the correct meaning. It follows the past-like present conjugation pattern with no vowel change. Examples:
 * Du solltest deine Mutter anrufen. – "You should call your mother." (Moral issue)
 * Du solltest Gemüse essen. – "You should eat vegetables." (Recommendation)
 * Wir sollen drinnen bleiben. – "We're supposed to stay inside." (Intention)

wollen
As we mentioned in the section on irregular verbs, this is a cognate to the English "will" but has a very different meaning. Fortunately, its meaning as a modal verb is nearly the same as its non-modal meaning, to express a desire to do something or for something to happen. This is similar, in both meanings, to the English "want". Examples:
 * Ich will meinem Mann ein Geschenk kaufen. – "I want to buy my husband a gift."
 * Wir wollen ihm nicht schaden. – "We don't want to harm him."

lassen
This is a cognate to the English "let" and often means "to allow" or "to give permission". So it's meaning is closely related to dürfen, which is modal, and so it follows that lassen is at least "semimodal". Perhaps "modal-like" or "modal adjacent" would work here as well. There are some differences between this and the six "canonical modal" verbs. First, it's not a past-like present verb like the others, just an ordinary stem-changing verb with the a changing to ä in the second (informal) and third person singular. Second, an additional object, the person or thing that's being "allowed", needs to be included. This will have the accusative case, which means the sentence as whole can have two accusative objects. The one that relates to lassen comes first, and the one relating to the infinitive verb comes later. There are many other meanings for this verb; a dictionary is a better place for most of them. But another one that's relevant here is "to have (someone) do (something)" or "to make (someone) do (something)". Again, with multiple meanings you have to use context to understand what is actually meant. Examples:
 * Lass mich dich küssen.  – "Let me kiss you."
 * Er lässt mich sein Haus bauen. – "He's having me build his house."
 * Der Rauch lässt den Alarm schrillen. – "The smoke is setting off the alarm."
 * Literally, "The smoke is causing the alarm to sound (shrilly)."

Compound verbs
German, as we know, likes to combine words to form compound words, sometimes novel ones which are only used in a single sentence. When this happens with two verbs, the result looks like one of them is being used as a modal verb and this is another edge case. To translate these compounds into English, you'd typically use the "-ing" form for the part of the compound that's in the infinitive. For example: Another possibility is to convert the "bare" infinitive in German to the "to" infinitive in English. These formulas don't always work though and sometimes you just have to find different phrasing:
 * Wir gehen wandern. – "We're going hiking."
 * Mein Kind lernt lesen. – "My child is learning to read."
 * Ich gehe einen Kaffee trinken. – "I'm going for a coffee."

These are not a true modal verbs since only certain combinations are possible. For example gehen would only be used for certain activities, presumably those which can only be done at another location. You can see the true nature of these compound verbs in the infinitive; they're similar to ordinary separable verbs except that the prefix, in this case a verb, is separated from the other verb by a space. So:
 * Wir werden wandern gehen. – "We will go hiking."
 * The infinitive is wandern gehen.
 * Mein Kind will lesen lernen. – "My child wants to learn to read."
 * The infinitve is lesen lernen.
 * Darf ich einen Kaffee trinken gehen? – "May I go for a coffee?"
 * The infinitve is trinken gehen.

You may see some of these compounds included in dictionaries. Of particular note is:
 * spazieren gehen – "to go for a walk"

Infinitive dropping
When the infinitive verb associated with a modal verb is implied by context and the rest of the sentence, it's not unusual to simply drop it. This often occurs:
 * With the generic verbs machen and tun. For example:
 * Das kannst du nicht. – "You're not allowed to do that."
 * With a phrase for a location and the verbs gehen and kommen. For example:
 * Wir dürfen ins Haus. – "We're allowed (to go/come) in the house."
 * Du musst weg. – "You have to go."
 * This can also be parsed using the separable verb wegmüssen. Both interpretations use the same words and have the same meaning.
 * With the name of a language and können.
 * Ich kann Niederländisch. – "I know Dutch."
 * In this case können can be replaced with kennen without changing the meaning much.

Negation with modal auxiliaries
Negation in German works differently from English when it comes to müssen. With the English "must" the negation is applied to the infinite verb. So in "You must not go," the meaning is that "not going" is the only possibility. In German, the negation is applied to the auxiliary verb or the sentence as a whole. So Du musst nicht gehen, means that it's false that "You must go." In other words it means "You don't have to go," rather than "You must not go." This is quite a difference in meaning and it can be quite confusing to English speakers. But the same issue exists with most of the modal auxiliaries to varying degrees, and it's a very good idea to translate the meaning to an English expression involving "to", at least mentally, before attempting to translate the negation. So think of the following more complicated phrases instead of the word for word translation when dealing with negation.
 * dürfen – "to be allowed to"
 * können – "to be able to"
 * müssen – "to have to"
 * wollen – "to want to"

For example:
 * Wir dürfen die Kekse nicht essen. – "We're not allowed to eat the cookies." (Not "We're allowed to not eat the cookies.")
 * This is the way you'd say "We must not eat the cookies."
 * Ich kann es nicht fassen. – "I'm not able to believe it." or "I can't believe it." (Not "I'm able to not believe it.)

It seems sollen is an exception to this; negations involving sollen are applied to the infinitive.

Modal adverbs
Another way to express modality is to use modal adverbs. Modal adverbs, also called modal particles, are words that add a certain flavor or mood to a sentence. These don't really exist in English, though this is arguable. Their meaning may also depend strongly on context, so modal adverbs are often difficult to translate. You may even see them left untransated when German is translated in to English, which may give the impression that they don't really have a meaning. Even the definition or a modal adverb is rather vague and there doesn't seem to be a universally agreed upon list of them; and there is some grey area between modal adverbs and sentence adverbs (for example natürlich ― "naturally, of course", leider ― "unfortunately", vielleicht ― "perhaps"). Many of these words also function as ordinary adverbs or other parts of speech, making the boundaries even fuzzier. But they have certain common characteristics that may serve to define the group:
 * They modify the rest of the sentence rather than the verb itself, a trait they share with sentence adverbs. For this reason they can't be used to answer a question starting with "when", "where" or "how".
 * They don't have a specific meaning, at least not a logical one, but mainly serve to convey a feeling about the sentence.
 * Thay are usually placed immediately after the verb, or at least in the midddle of the sentence, and can't be moved in front of it like other adverbs. This is one way to distinguish them from sentence adverbs. Since they don't convey actual information, they are rarely placed in a prominent prosition at the end of a sentence, and never at the beginning. This is why they are often called particles rather than adverbs. In cases where they don't immediately follow the verb, they're probably meant to highlight a particular phrase. They might also be bumped away from the verb by a word which also likes to be close to it.
 * They aren't stressed in speech. Again, because they don't convey actual information, there's no reason to accent them verbally.
 * When several occur in a single sentence, they must be kept together.

We'll provide a list here, which will hopefully clarify what we mean by these characteristics, but keep in mind that there is no universal agreement on what should or should not be included in this list. We have met many of these words before since they are also used as other parts of speech. We won't attempt to include all possible meanings for these words, since that task is better suited to a dictionary, but we'll try to include enough of the important meanings so you can get a feel for how the words are used.


 * doch: This can express that what is being said is a reminder of what is already known or to point out something apparent:
 * Es ist doch ein schöner Tag, gehen wir spazieren. – "It's a beautiful day, let's go for a walk."
 * This might be said when you're already outside and can see what a nice day it is.
 * In this sense it overlaps with ja, to be covered below. But while ja is usually friendly, doch may convey some impatience:
 * Lass den Tiger in Ruhe, er ist doch gefährlich. – "Leave the tiger alone, he's dangerous (as you ought to know)."


 * ja: This says that a fact is already known or common knowledge, so it implies that what is being said is a friendly reminder.
 * Wir sprechen Deutsch denn wir sind ja in Deutschland. – "We speak German because we are in Germany."
 * In this case everyone knows what country they are in, so the part about being in Germany is just a reminder.
 * It can be used to introduce a fact as a small consession before a contrasting fast. In this sense it my be translated by starting the sentence with "sure".
 * Schokolade ist ja lecker, aber ich mag auch Vanille. – "Sure, chocolate is tasty, but I also like vanilla."


 * nur: This is used in questions to express a sense of urgency. It might be translated as "just".
 * Was soll ich nur tun? – "Just what am I supposed to do?"
 * You might say this a panicky situation where it's clear that you must do something, but you can't seem to think of anything.


 * schon: In an imperative this conveys a sense of urgency or impatience.
 * Komm schon. – "Come on./Hurry up."
 * This might be said to someone who is lagging behind and you don't feel like waiting for them.
 * In a regular sentence it may express confidence or emphasize the point, especially when you're trying to inspire confidence or hope in the other person.
 * Wir werden schon überleben. – "I'm sure we will survive."
 * Since schon has another meaning as an ordinary adverb, it should be avoided as a modal adverb when it would cause confusion.


 * wohl: This can be used where you might say something "must be" so, meaning you didn't actually see it but you're relatively certain anyway.
 * Du machst wohl Witze! – "You must be joking!" (Literally: "You must be making a joke!*)