Modal verbs

Modal verbs dürfen, können, mögen, müssen, sollen and wollen form a multiple predicate when combined with the infinitive of a full verb, thus changing its content. In this case, the modal verb is connected with the infinitive without the use of the word zu.

Modal verbs modify the content of the infinitive with which they are linked. Each modal verb has one or more meanings. These multiple meanings of the modal verbs characterize the relation between the subject and the predicate. In this case, we refer to the objective meaning of modal verbs. 

The following table shows an overview of these meanings:

There is also a second function of modal verbs. It involves meanings of the modal verbs that refer to the attitude of the speaker towards his/her statement. In this case, we refer to the subjective meaning of modal verbs. Through the subjective meaning of the modal verbs, either the likelihood of a fact is assessed (hypothesis) or speech is reported i.e. the words of somebody.

Besides modal verbs, there are also other verbs that can modify the meaning of an infinitive in a similar way. These verbs are connected with an infinitive that is always accompanied by zu.

Modal verbs can also be used as full verbs; in this case, they are not linked to an infinitive.

This is often the case of elliptically formed sentences, in which the infinitive is omitted because its meaning can be deduced by the context.