Past assumptions (müssen, können, dürften)

Playing Detective: Past Assumptions

In German, you can use subjective modal verbs to express how certain you are about an assumption.

To make deductions about a past event, combine a conjugated modal verb with the Perfekt infinitive (a past participle + haben or sein).

  • The conjugated modal verb takes position two.
  • The Perfekt infinitive goes at the very end of the sentence.

When you are highly confident about your deduction ("must have"), use müssen.

He must have smashed the window with a paving stone.
Er muss das Fenster mit einem Pflasterstein eingeschlagen haben.

Just like in the regular Perfekt tense, verbs expressing motion or a change of state require sein as their helper verb instead of haben.

According to the police, someone must have broken in last night.
Laut der Polizei muss jemand letzte Nacht eingebrochen sein.
He must have slipped away unnoticed through the garden afterwards.
Er muss danach unbemerkt durch den Garten entwischt sein.

Varying Degrees of Certainty: "dürften" and "können"

Adjust the modal verb to match your level of certainty:

  • dürften (the Konjunktiv II form of dürfen): Strong probability ("probably did" or "is likely to have").
  • können: Possibility ("could have").
The dog was probably sleeping.
Der Hund dürfte geschlafen haben.
The burglar is likely to have looked for not only the money, but also the jewelry.
Der Einbrecher dürfte nicht nur das Geld, sondern auch den Schmuck gesucht haben.
He could have injured himself on this shard.
Er kann sich an dieser Scherbe verletzt haben.
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