Making logical deductions
When you are sitting quietly in a hideout trying to identify rare birds through your binoculars, you often have to make guesses based on the clues you see. In German, just like in English, you can use modal verbs to express assumptions and logical deductions.
Because these are modal verbs, the conjugated modal takes position 2 in the sentence, while the main verb goes to the very end in its infinitive (dictionary) form.
Strong assumptions with "müssen"
When you have clear evidence and are almost completely certain about your deduction, use müssen (must).
| It must be a female because the beak is yellow. | Es muss ein Weibchen sein, denn der Schnabel ist gelb. |
| It must be very cold inside the hideout. | Innerhalb des Verstecks muss es sehr kalt sein. |
Possibilities with "können"
If you are less certain and simply stating that something is possible, use können (can/could).
| There could be colorful feathers on the wing. | Es können bunte Federn auf dem Flügel sein. |
Impossibilities with "können nicht"
When the evidence points the other way and you deduce that something "cannot" be true, combine können with a negation like nicht.
| This gray bird cannot be the male. | Dieser graue Vogel kann nicht das Männchen sein. |
Adding extra certainty
You can make your assumptions even stronger by adding adverbs. The word bestimmt means "certainly" or "definitely," and it pairs perfectly with these modal verbs to emphasize your confidence.
| certainly | bestimmt |
| It must definitely be a rare species. | Es muss bestimmt eine seltene Art sein. |
