When Catalan speakers infer a likely explanation from evidence, they commonly use deure + infinitive: Deu ser tard “It must be late / It is probably late.” This is epistemic modality: the speaker is evaluating how likely a proposition is, not imposing a duty. The distinction is essential because standard Catalan normally uses haver de + infinitive for obligation.
The inferential structure
The pattern has two parts:
- a finite form of deure, agreeing with the inferred subject;
- a bare infinitive that names the likely state or event.
La botiga deu estar tancada; no hi ha cap llum encesa.
The shop must be closed; there aren't any lights on.
Amb aquest trànsit, deuen arribar tard.
With this traffic, they will probably arrive late.
Si no recordes la contrasenya, deus tenir-la apuntada en algun lloc.
If you don't remember the password, you probably have it written down somewhere.
The construction presents a conclusion as probable but not directly known. A natural English translation may use “must,” “probably,” or “I suppose.” None is a fixed equivalent: the Catalan form encodes the speaker’s inferential stance.
Present forms and agreement
The present of deure is irregular enough to deserve a complete working paradigm:
| Person | Present | Inference with ser |
|---|---|---|
| jo | dec | dec ser l'últim |
| tu | deus | deus ser a prop |
| ell / ella / vostè | deu | deu ser fora |
| nosaltres | devem | devem ser els primers |
| vosaltres | deveu | deveu ser de vacances |
| ells / elles / vostès | deuen | deuen ser al jardí |
Do not confuse first-person dec “I must/probably...” with the number deu “ten,” or third-person deu with Déu “God.” The written accent and capitalization of Déu are meaningful.
Dec haver deixat el carregador a l'hotel, perquè no és dins la maleta.
I must have left the charger at the hotel, because it isn't in the suitcase.
The first person is possible when speakers infer something about their own forgotten action or state. Third-person forms are simply more frequent because we often infer facts about other people and situations.
Present inference with a simple infinitive
Use present deure + simple infinitive when the inferred state or event is simultaneous with, or later than, the moment of inference.
Ara deuen estar reunits; prova de trucar-los després de les dotze.
They must be in a meeting now; try calling them after twelve.
Aquest cap de setmana deu nevar al Pirineu.
It will probably snow in the Pyrenees this weekend.
With a stative infinitive such as ser, tenir, or saber, the inference normally concerns a current state. With a future-time expression, the same present modal can estimate a later event. Discourse time, not an English tense label, determines the reading.
Past inference with the perfect infinitive
To infer that an event was already completed before the present inference, use present deure + perfect infinitive: deure + haver + participle.
No hi ha pa: algú se'l deu haver acabat.
There is no bread: someone must have finished it.
La Núria no respon; deu haver apagat el mòbil.
Núria isn't answering; she must have switched off her phone.
Les entrades es deuen haver exhaurit en pocs minuts.
The tickets must have sold out in a few minutes.
The perfect infinitive is haver + participle, not a finite perfect. Only deure bears person and tense: deu haver sortit, deuen haver sortit. The participle stays in its compound-tense form and does not agree with the subject.
A past viewpoint: devia
When the act of inference itself belongs to a past narrative viewpoint, use the imperfect devia, devies, devia, devíem, devíeu, devien. The simple infinitive is simultaneous with that past viewpoint; the perfect infinitive is earlier than it.
Quan hi vam arribar, el porter devia dormir.
When we arrived, the caretaker was probably asleep.
La porta era oberta: algú devia haver entrat abans que nosaltres.
The door was open: someone must have entered before us.
The English forms “must have been sleeping” and “must have entered” can look similar, but Catalan marks the time relationship internally. Devia dormir locates the probable sleeping at the past reference point; devia haver entrat locates entry before it.
Evidence strength and alternatives
Deure + infinitive usually conveys a fairly plausible conclusion, not absolute certainty. Intonation, context, and modifiers can strengthen or weaken it. Compare:
| Form | Typical stance |
|---|---|
| Potser és a casa. | one possibility among others |
| Pot ser que sigui a casa. | being at home is possible |
| Deu ser a casa. | available evidence makes this likely |
| Segurament és a casa. | speaker explicitly rates it as likely |
| És a casa. | asserted as fact |
This is not an exact probability scale. A speaker may choose deu ser to avoid taking full responsibility for a claim, while another chooses segurament with the same evidence. Pragmatics and evidential responsibility matter.
Negation and scope
No + deure + infinitive generally means that the speaker infers the negative proposition: No deu ser a casa “He is probably not at home.” It does not normally prohibit the action.
No deuen saber que hem canviat l'hora de la reunió.
They probably don't know that we've changed the meeting time.
No es deu haver adonat de l'error.
She probably hasn't noticed the mistake.
If you mean a prohibition or absence of obligation, choose the appropriate construction: No has d'entrar can mean “you must not enter” in context, while No cal que entris means “you don't need to come in.” See haver de for obligation.
Weak pronouns in simple and perfect chains
With a simple infinitive, the pronoun can usually precede deure or attach to the infinitive:
Ho deu saber. / Deu saber-ho.
She must know it.
With a perfect infinitive, premodal placement is particularly natural: s'ho deu haver imaginat. Enclitic placement attaches the pronoun to infinitival haver: deu haver-s'ho imaginat. Never attach it to the participle.
Els documents, els deuen haver enviat aquest matí. / Deuen haver-los enviat aquest matí.
They must have sent the documents this morning.
No preposition de
Standard Catalan uses deure + infinitive, with no linking preposition: deu ser, deu arribar, deu haver sortit. Deure de + infinitive copies Spanish deber de and is not the standard Catalan construction. The fact that the verb itself ends in -ure can make the boundary hard to hear, but the syntax is unambiguous in writing.
Inference is not obligation
The difference between deure and haver de is semantic, not merely stylistic:
La metgessa deu arribar a les deu.
The doctor will probably arrive at ten. (inference)
La metgessa ha d'arribar a les deu.
The doctor has to arrive at ten. (requirement or schedule)
The same real-world event may support either sentence, but the speaker performs a different act. The first estimates; the second states a necessity.
Mini-dialogue
—Per què no obre ningú? —Deuen haver tancat abans per la festa local.
—Why is nobody opening up? —They must have closed early for the local holiday.
—I l'avís de la porta? —No el devem haver vist quan hem entrat.
—What about the notice on the door? —We must not have seen it when we came in.
The speakers revise their understanding from visible evidence. Neither sentence reports certain knowledge.
Register and regional notes
Inferential deure + infinitive is standard in Central, Valencian, Balearic, Northwestern, Northern, and Alguerese Catalan and works in (informal) speech as well as (formal) prose. Other devices—potser, segurament, the future of probability, or lexical phrases such as pel que sembla—may be more frequent in particular communities or genres. They are alternatives in discourse, not evidence that deure changes into an obligation verb. In careful IEC- and AVL-aligned usage, keep probability deure distinct from obligation haver de.
Common Mistakes
❌ Deu de ser a l'oficina.
Incorrect Spanish-influenced linking preposition — Catalan deure takes a bare infinitive.
✅ Deu ser a l'oficina.
She must be at the office.
❌ Dec entregar el formulari avui.
Incorrect for obligation — deure expresses inference in standard Catalan.
✅ He d'entregar el formulari avui.
I have to hand in the form today.
❌ No és aquí: deu marxar fa una hora.
Incorrect time relation — an earlier completed event needs the perfect infinitive.
✅ No és aquí: deu haver marxat fa una hora.
He isn't here: he must have left an hour ago.
❌ Les cartes deuen haver arribades avui.
Incorrect — the participle in the perfect infinitive does not agree with the subject.
✅ Les cartes deuen haver arribat avui.
The letters must have arrived today.
❌ Ahir a les deu deu dormir.
Incorrect for an inferred state at a past reference point — use imperfect devia.
✅ Ahir a les deu devia dormir.
Yesterday at ten, he was probably asleep.
Key Takeaways
- Deure + bare infinitive expresses an inference, not standard obligation.
- Present deure plus a simple infinitive infers a simultaneous or later situation: deu dormir, deu arribar demà.
- Present deure plus haver + participle infers an earlier completed event: deu haver sortit.
- Imperfect devia moves the viewpoint into the past; devia haver sortit is earlier than that past point.
- No deu... normally makes a negative inference, not a prohibition.
- Use haver de for obligations, and never insert Spanish-influenced de between deure and its infinitive.
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