7.14 dürfen

Modal auxiliaries have a full range of tenses, unlike the English modal verbs. The various possibilities are illustrated for können:

Especially in everyday speech, the main verb can be omitted in certain contexts if the meaning is clear. This is common with verbs of motion (e.g. gehen, kommen, fahren) and with the verb tun:

tense infinitive type

present infinitive Er kann es machen. He can do it. present perfect infinitive Er kann es gemacht haben. He can have done it. future infinitive Er wird es machen können. He will be able to do it. past infinitive Er konnte es machen. He was able to do it. perfect infinitive Er hat es machen können. He has been/was able to do it. pluperfect infinitive Er hatte es machen können. He had been able to do it. past subj. infinitive Er könnte es machen. He could do it. past subj. perfect infinitive Er könnte es gemacht haben. He could have done it. pluperf.subj. infinitive Er hätte es machen können. He would have been able to do it.

Er darf nicht nach Paris.[fahren] He isn’t allowed to go to Paris. Ich will heute nicht in die Disko.[kommen] I don’t want to come to the disco today. Das konnten wir einfach nicht.[tun] We just couldn’t do it.

dürfen most often expresses permission ( ‘be allowed’, ‘may’):

Sie dürfen hereinkommen. Sie durften hereinkommen. They may/are allowed to come in. They were allowed to come in.

With nicht, this is the equivalent of English ‘must not’:

Sie dürfen nicht hereinkommen. They mustn’t/are not allowed to come in.

The subjunctive II of dürfen expresses probability ( ‘will (probably)’):

With nicht, the subjunctive II of dürfen corresponds to English ‘shouldn’t’ or ‘oughtn’t’:

Das dürfte reichen. That will probably be enough. Die Jacke dürfte ein Vermögen gekostet haben. That jacket will have cost a fortune.

Das dürfte sie gar nicht wissen. She ought not to know that. Das hätte er nicht machen dürfen. He shouldn’t have done that.