Poder, Deure, and Potser | Catalan Grammar

English uses can, may, might, must, and perhaps across several kinds of modality. Catalan divides that work among poder + infinitive for ability, permission, and open possibility; deure + infinitive for a reasoned inference; and the sentence adverb potser for “perhaps/maybe.” Choosing among them means deciding what kind of evidence or authority the speaker claims, not matching one English word to one Catalan form.

Form	Grammar	Main meanings
poder + infinitive	finite modal verb + bare infinitive	ability, permission, situational possibility
deure + infinitive	finite modal verb + bare infinitive	probable inference based on evidence
potser + clause	modal adverb + normally indicative clause	speaker presents a possibility without asserting it

Puc acabar l'informe aquesta tarda.

I can finish the report this afternoon. (ability or availability)

La Marta deu ser al tren; no contesta.

Marta must be on the train; she isn't answering. (inference)

Potser la Marta és al tren.

Maybe Marta is on the train. (open possibility)

Poder + infinitive

Poder agrees with the person who has the ability, receives permission, or is involved in the possibility. It takes the infinitive directly, with no a, de, or que.

Person	Present of poder	Example
jo	puc	puc venir
tu	pots	pots venir
ell / ella / vostè	pot	pot venir
nosaltres	podem	podem venir
vosaltres	podeu	podeu venir
ells / elles / vostès	poden	poden venir

The first-person puc is irregular. The other present forms alternate between pot-/pod- in a pattern that must simply be learned. Full tense paradigms belong in the reference page for poder.

Ability and circumstances

No puc aixecar aquesta caixa sense ajuda.

I can't lift this box without help.

Ara ja podem entrar: han obert la porta.

We can go in now: they've opened the door.

For learned skills, Catalan often uses saber + infinitive, as English also allows “know how to”: Sé nedar, però avui no puc nedar perquè m'he fet mal al braç. The first clause states the acquired skill; the second denies present circumstances.

Permission

—Puc seure aquí? —Sí, i tant.

—May I sit here? —Yes, of course.

Els visitants no poden fer fotografies en aquesta sala.

Visitors may not take photographs in this room.

The conditional podria / podries / podríem... softens requests and suggestions: Em podries donar un cop de mà? It does not make the situation literally conditional every time; politeness often recruits hypothetical distance.

Open possibility

Demà pot ploure a la tarda, segons la previsió.

It may rain tomorrow afternoon, according to the forecast.

Here the third-person singular pot has an impersonal or weather-related subject. The clause expresses a possible event, not someone’s ability.

Deure + infinitive: inference, not standard obligation

In contemporary standard Catalan, deure + infinitive normally expresses a probable inference: the speaker reasons from available evidence. It takes no preposition.

Ja són les nou; els convidats deuen ser a punt d'arribar.

It's already nine; the guests must be about to arrive.

No trobo les claus: me les dec haver deixat al despatx.

I can't find my keys: I must have left them at the office.

For obligation, the standard everyday construction is haver de + infinitive, not deure + infinitive: He de marxar “I have to leave.” The dedicated page on deure for probability explains present and past inference in depth.

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Ask what the speaker is doing. Issuing a requirement calls for haver de; drawing a likely conclusion calls for deure; leaving several outcomes open calls for poder or potser.

Potser is one word and means “perhaps/maybe.” It does not agree with a subject, and it can modify a whole clause. In ordinary standard Catalan it is followed by the indicative, because the adverb itself already marks uncertainty.

Potser arribem cinc minuts tard perquè hi ha obres.

Maybe we'll arrive five minutes late because there are roadworks.

Potser no ho saben encara; ningú no els ho ha explicat.

Maybe they don't know yet; nobody has explained it to them.

Do not confuse potser with pot ser, two words: pot ser is the verb poder plus ser, meaning “it can/may be.” The two-word sequence can be followed by an adjective, noun phrase, or a que-clause.

Pot ser útil guardar-ne una còpia.

It may be useful to keep a copy.

Pot ser que arribin tard.

It may be that they arrive late.

In pot ser que, the subordinate proposition is presented as possible rather than asserted, so the verb is subjunctive: arribin. By contrast, potser arriben tard uses indicative arriben. The visual space changes the syntax. Regional speech also shows the subjunctive after potser, especially in the variant potser que. As a general-standard baseline, use potser + indicative for ordinary probability. A separate (informal, regional) use of potser que + subjunctive can soften a suggestion or command—Potser que marxem! “Perhaps we should leave!”

Degrees of commitment

These expressions are not a mathematical certainty scale, but they invite different readings:

Potser és a casa offers “at home” as one possibility.
Pot ser a casa says being at home is possible in the circumstances.
Deu ser a casa presents “at home” as the speaker’s likely conclusion.
És a casa asserts the proposition as fact.

Hi ha llum a dins: en Pau deu ser a casa.

There's a light on inside: Pau must be at home.

The evidence in the first clause licenses the inference. If there is no particular evidence and the speaker is merely considering options, potser is usually more honest.

Tense, aspect, and mood

The finite modal carries tense and mood. The infinitive stays nonfinite:

podia venir — ability or possibility viewed as ongoing/background in the past;
va poder venir — a bounded opportunity, often understood as realized;
deu haver vingut — present inference about an earlier completed event;
devia estar dormint — past viewpoint on a situation likely in progress then.

Al final va poder canviar el bitllet sense pagar cap recàrrec.

In the end, she managed to change the ticket without paying a surcharge.

Quan vas trucar, devia estar conduint.

When you called, he was probably driving.

Surrounding syntax can put the modal in the subjunctive. No crec que pugui venir uses pugui because the possibility is under negated belief. Do not choose mood from the English word “might” alone.

Weak-pronoun placement

With poder and deure, weak pronouns commonly precede the finite modal or attach to the infinitive. Both positions preserve the same basic reference.

Ho podem parlar demà. / Podem parlar-ho demà.

We can discuss it tomorrow.

S'ho deu haver imaginat. / Deu haver-s'ho imaginat.

She must have imagined it.

With potser, there is no infinitival chain for a pronoun to climb through. The pronoun takes its normal place before the finite verb: Potser l'han avisat.

Mini-dialogue

—Podem deixar les bicicletes aquí? —Potser sí, però ho hauríem de preguntar.

—Can we leave the bicycles here? —Maybe, but we should ask.

—On és l'encarregada? —Deu haver sortit a dinar; l'abric no és al penjador.

—Where is the manager? —She must have gone out for lunch; her coat isn't on the hook.

The first exchange asks about permission and answers cautiously. The second uses visible evidence to support an inference.

Register and regional notes

Poder, inferential deure, and potser are standard throughout the Catalan-speaking domain. They occur in (informal) conversation and (formal) writing. Pronunciation and some inflected forms vary regionally, but the syntactic contrasts on this page remain available in Central, Valencian, Balearic, Northwestern, Northern, and Alguerese Catalan. In careful writing, avoid importing Spanish deber de: standard Catalan uses deure + infinitive without de.

Common Mistakes

❌ Puc a venir després de dinar.

Incorrect — poder takes the infinitive directly, with no a.

✅ Puc venir després de dinar.

I can come after lunch.

❌ Deus de tenir molta son.

Incorrect Spanish-influenced form — inferential deure takes no de.

✅ Deus tenir molta son.

You must be very sleepy.

❌ Demà dec presentar la sol·licitud.

Incorrect for obligation in standard Catalan — deure expresses inference, not a requirement.

✅ Demà he de presentar la sol·licitud.

I have to submit the application tomorrow.

⚠️ Potser vingui més tard.

Regional rather than the general-standard baseline after bare potser; use the indicative for neutral general-standard Catalan.

✅ Potser ve més tard.

Maybe she'll come later.

❌ Pot ser arriba més tard.

Incorrect mixture — verbal pot ser needs que before a finite possibility clause.

✅ Pot ser que arribi més tard.

She may arrive later.

Key Takeaways

Poder + bare infinitive expresses ability, permission, or situational possibility.
Deure + bare infinitive expresses a likely inference; standard obligation uses haver de.
Potser is one invariable adverb and normally takes an indicative clause.
Pot ser is two words, the verb poder plus ser; pot ser que introduces a possible, subjunctive proposition.
Tense and mood show viewpoint and assertion status. English can, might, and must cannot predict the Catalan form on their own.
Weak pronouns can climb with verbal modals, but potser is not a verb and creates no pronoun-climbing domain.

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Three different modal structures