Subjective Modal Verbs in German: wollen, sollen, müssen for Hearsay and Doubt

German modal verbs have a second, subjective life. Beyond their objective meanings (ability, permission, obligation), they let the speaker comment on the truth of a claim — and that meaning usually surfaces with a perfect infinitive (… gesehen haben) or a plain infinitive of state (… reich sein).

• wollen = the subject asserts something about itself, while the speaker stays skeptical: Er will alles gesehen haben ("he claims to have seen everything — but I doubt it").
• sollen = hearsay or rumour reported from others: Sie soll sehr reich sein ("she is said to be very rich").
• müssen / dürfte = the speaker's own inference: Er muss krank sein (strong conclusion), Sie dürfte schon zu Hause sein (cautious guess).

The crucial contrast is wollen vs. sollen: wollen puts the claim in the subject's own mouth (and signals doubt), whereas sollen attributes it to an outside source. Confusing them reverses who is making the claim. Distinguish all of this carefully from the objective readings, where wollen means "to want" and sollen means "to be supposed to / ought to."