Modals of Deduction
In Danish, modal verbs like må (must), kan (can/might), and vil (will) are not just used to express obligation, ability, or future actions. They can also express deduction—how certain you are about a situation based on the clues at hand.
Just like other modal constructions, these verbs are conjugated in the present tense and are followed directly by the bare infinitive of the main verb (such as være, meaning "to be").
Strong Deductions with "Må"
When the evidence at a crime scene points to a clear and obvious conclusion, use må to mean "must."
| The lipstick on the cigarette in the ashtray must belong to a woman. | Læbestiften på cigaretten i askebægeret må tilhøre en kvinde. |
| The window is smashed, so the thief must be here. | Vinduet er knust, så tyven må være her. |
Probability with "Vil"
To state that something is highly likely or to make a logical prediction, use vil (will). To make the deduction clear, vil is very frequently paired with the adverb sandsynligvis (probably).
| probably (likely) | sandsynligvis |
| The murderer will probably leave a piece of evidence behind. | Morderen vil sandsynligvis efterlade et bevis. |
| It will probably be difficult to solve the theft without the handkerchief behind the sofa. | Det vil sandsynligvis være svært at opklare tyveriet uden lommetørklædet bagved sofaen. |
Possibility and Impossibility with "Kan"
When you are analyzing clues and something is merely possible (could be / might be), use kan.
| It looks as if it is a suicide, but the evidence might be fake. | Det ser ud som om det er et selvmord, men beviset kan være falskt. |
Conversely, adding the negation ikke to kan is the standard way to deduce that a scenario is impossible (cannot be).
| It cannot be true that the murderer is still in the building. | Det kan ikke være sandt at morderen stadig er i bygningen. |