Modalverben zur Vermutung
You already know müssen (have to), dürfen (be allowed to), and können (can/be able to) from A1-2 - their "objective" meanings about obligation and permission. In their Konjunktiv II form (Lesson 169), these same modal verbs shift to a completely different job: guessing how likely something is.
| Konjunktiv II form | Certainty level | Meaning |
|---|---|---|
| müsste | very likely, strong logical conclusion | must be |
| dürfte | probably true | is probably |
| könnte | possible, genuinely uncertain | could be |
Er müsste zu Hause sein - sein Auto steht vor der Tür. (He must be home - his car is out front.)
Sie dürfte um fünf Uhr ankommen. (She's probably arriving at five.)
Das könnte stimmen, aber ich bin nicht sicher. (That could be true, but I'm not sure.)
Quick check: which of müsste/dürfte/könnte expresses the strongest certainty?
To say something is impossible - not just unlikely - use kann nicht or kann nicht sein.
Das kann nicht sein! (That can't be true!)
Er kann nicht schon da sein, der Flug landet erst um zehn. (He can't be there already, the flight doesn't land until ten.)
Quick check: "That can't be true!" - Das ______ nicht sein!
Context tells you which meaning is active: "Ich müsste um acht da sein" in a work context still means "I have to be there at eight" (objective, obligation). But "Er müsste jetzt zu Hause sein" without any obligation context is a guess (subjective, probability). Listen for whether the sentence is about a rule/duty or a conclusion you're drawing.
Quick check: does context or the word form tell you whether müsste means "have to" or "must be" (a guess)?
1. "She's probably arriving at five." - Sie ______ um fünf Uhr ankommen.
2. What grammatical form are müsste, dürfte, and könnte?
Aligned with standard Goethe-Zertifikat B1 / telc B1 exam syllabus topics.
Want to practice guessing about real situations in your life with the right level of certainty? Ask your teaching agent.