A2
pouvoir, vouloir, devoir, savoir
How the French modal verbs work, why they take no preposition, and the difference between savoir and pouvoir.
| pouvoir | can, be able to |
| vouloir | want |
| devoir | must, have to |
| savoir | know how to |
All four are followed directly by an infinitive, with nothing in between.
Je peux venir ce soir.
I can to-come this evening
I can come this evening.
Tu dois partir maintenant.
you must to-leave now
You have to leave now.
Je peux nager depuis l’âge de cinq ans.
Je sais nager depuis l’âge de cinq ans.
A skill you learned takes savoir. Pouvoir would say you have been in a position to swim since you were five, which is not what anyone means. Note also that neither takes a preposition before the infinitive, unlike j’essaie de venir or j’apprends à nager.
savoir against pouvoir
Savoir is a learned skill. Pouvoir is being in a position to do it now.
Je sais nager, mais je ne peux pas aujourd’hui.
I know to-swim, but I not can not today
I can swim, but I can’t today.
English uses can for both. Choosing pouvoir for a skill sounds like you are talking about this afternoon.
The conditional softens all of them
Je devrais partir.
I would-must to-leave
I ought to go.
Je dois is an obligation; je devrais is advice. Similarly je pourrais is I could, and je voudrais is the polite I’d like — see the conditional.
devoir also means to owe
Je te dois dix euros.
I to-you owe ten euros
I owe you ten euros.
With a noun it is owing; with an infinitive it is obligation.
In the past the meaning narrows
J’ai dû partir is I had to leave — and also I must have left. Context is the only guide, and French speakers rely on it without difficulty.