Modal verbs at B2 — full verbs, double infinitives, and the subjective use
By B2 you already use können, müssen, dürfen, sollen, wollen, mögen / möchten with infinitives. Three things still trip up advanced learners. (1) Modal as a full verb — without an infinitive: Ich kann Deutsch. = I know German. Er will einen Kaffee. = He wants a coffee. Ich mag dich. = I like you. Here the modal is a regular verb that takes a direct object. (2) Double infinitive in the Perfekt and Plusquamperfekt — when a modal pairs with another verb in a perfect tense, the past participle of the modal looks like an infinitive: Er hat kommen müssen. = He had to come. NOT Er hat kommen gemusst. The auxiliary is always haben, never sein. (3) Subjective use — modals don't just describe ability or obligation; they can express the speaker's stance toward the truth of a claim. Er muss krank sein. = He must be sick (= I'm convinced based on evidence). Er kann krank sein. = He may be sick (possibility). Er dürfte krank sein. = He's probably sick (polite guess). Er soll reich sein. = He's said to be rich (hearsay). Sie will Ärztin gewesen sein. = She claims to have been a doctor (her assertion, possibly false). The same modal is used objectively (real obligation/permission) and subjectively (degree of belief / source of claim) — context decides.
Modal as a full verb (no second verb)
All six modals can stand alone with a direct object or adverb. können = to know how / be able. Ich kann Deutsch. = I know German. Sie kann gut Klavier. wollen = to want. Er will einen Kaffee. = He wants a coffee. mögen = to like. Ich mag Schokolade. müssen = to have to / need to (with destination): Ich muss nach Hause. = I need to go home. (The verb 'go' is implied.) dürfen = to be allowed: Du darfst das nicht. sollen = to be supposed to. The Perfekt of these standalone uses is regular: Ich habe Deutsch gekonnt. Er hat einen Kaffee gewollt. Ich habe Schokolade gemocht. Here you DO use the proper Partizip II (gekonnt, gewollt, gemocht, gemusst, gedurft, gesollt), because there's no other infinitive in the clause.
Double infinitive — the Perfekt with two verbs
When a modal accompanies a full verb in a perfect tense, the rule flips: the modal's Partizip II looks like the infinitive. Er hat kommen müssen. = He had to come. Ich habe arbeiten können. = I was able to work. Sie hat gehen wollen. = She wanted to go. Wir haben warten sollen. = We were supposed to wait. Du hast nicht rauchen dürfen. = You weren't allowed to smoke. The pattern: haben + [main-verb-Infinitiv] + [Modal-Infinitiv]. The modal goes LAST. The auxiliary is always haben, even with movement verbs: Er hat schwimmen können. (NOT ist). In subordinate clauses with a double infinitive, the conjugated haben moves OUT of final position to BEFORE the two infinitives — a famous exception: … weil er hat kommen müssen. (not gekommen müssen and not kommen müssen hat). In speech, the Präteritum or simple Perfekt avoids the issue: Er musste kommen. is far more common than Er hat kommen müssen.
Subjective use — degrees of certainty
German modals carry a second life as epistemic markers — they label how sure the speaker is, or where the claim comes from. The verb form is the same; only context tells you which reading applies. müssen (subjective) = must, has to (= certainty based on evidence). Er muss krank sein. = He must be sick (the evidence forces the conclusion). können (subjective) = may, might (= possibility, weaker than müssen). Er kann krank sein. = He may be sick. dürfte (Konjunktiv II of dürfen) = is probably (= polite guess, slightly hedged). Er dürfte gegen sechs ankommen. = He'll probably arrive around six. mag (subjective) = may well, granted (concessive): Das mag stimmen, aber … = That may be true, but … In a typical scale: muss > dürfte > kann > mag in descending certainty.
Hearsay and claim — sollen, wollen
Two modals carry information about the SOURCE of the claim, not the speaker's certainty. sollen (subjective) = is said to, supposedly. Er soll sehr reich sein. = He's said to be very rich (someone else says so). Das Restaurant soll gut sein. = The restaurant is supposed to be good. The speaker is RELAYING someone else's claim and not vouching for it. wollen (subjective) = claims to, allegedly. The subject themselves makes the claim, often dubious. Sie will Ärztin gewesen sein. = She claims to have been a doctor (and we suspect she wasn't). Er will den Brief nicht gesehen haben. = He claims not to have seen the letter. Use wollen when you want to mark someone else's self-report with a hint of skepticism.
Subjective with the past — modal + Perfekt-infinitive
To make a subjective claim about the past, you use the modal in the present + the Perfekt-infinitive (Partizip II + haben/sein). Er muss krank gewesen sein. = He must have been sick. Sie kann das nicht gewusst haben. = She can't have known that. Er soll früher Sportler gewesen sein. = He's said to have been an athlete. Sie will alles allein gemacht haben. = She claims to have done it all alone. The modal stays present-tense; the embedded perfect carries the past meaning. This is a hallmark of upper-intermediate to advanced German.
Disambiguating objective vs subjective
Same word, two meanings. Er muss arbeiten. can be (a) objective: 'He has to work' (obligation), or (b) subjective: 'He must be working (right now)' — the second reading needs context like a strong inference. With a state verb (sein, wissen, kennen), the subjective reading is much more natural: Er muss krank sein is almost never 'he is obliged to be sick'; it's 'he must be sick'. With an action verb, the objective reading is usually preferred unless context forces the inferential one (an 'wahrscheinlich' or context like staring at evidence). German speakers also reinforce the subjective reading with adverbs: wohl (presumably), sicher (surely), bestimmt (definitely). Er muss wohl krank sein.
Quick reference table
Objective uses (already known): können = ability, permission; müssen = necessity, obligation; dürfen = permission; sollen = expectation/order from someone else; wollen = wish/intention; mögen / möchten = liking / polite wish. Subjective uses (this lesson): müssen = must (certainty), dürfen → dürfte = probably (polite guess), können = may/might (possibility), mag = may well (concessive), sollen = is said to (hearsay), wollen = claims to (self-report, often skeptical). For the past, all six combine with Partizip II + haben/sein (Perfekt-infinitive).
