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Linglib.Fragments.Portuguese.Modals

Portuguese Modal Verb Entries [Fer23] #

Portuguese has a tripartite modal system with lexicalized weak necessity, unlike Spanish (where cognate deber is strong necessity) or English (where ought/should are ambiguous between X-marked and unmarked readings).

The six modal forms occupy two dimensions: modal force (possibility / weak necessity / strong necessity) × X-marking (present / past imperfect):

ForceUnmarked (present)X-marked (past imperfect)
Possibilitypodepodia
Weak necessitydevedevia
Strong necessitytem quetinha que

X-marking does not change modal force — it shifts the modal parameters (modal base or ordering source), signaling presupposition suspension.

Helper #

Present tense (unmarked) modal entries #

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def Portuguese.Modals.poder :
Semantics.Modality.ModalItem

pode 'can/may' — possibility modal, all flavors.

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    def Portuguese.Modals.dever :
    Semantics.Modality.ModalItem

    deve 'ought/should' — weak necessity modal, all flavors. Portuguese lexicalizes weak necessity as a distinct root, unlike Spanish deber (strong necessity) or English ought (ambiguous).

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      def Portuguese.Modals.terQue :
      Semantics.Modality.ModalItem

      tem que 'must/have to' — strong necessity modal, all flavors.

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        Past imperfect (X-marked) modal entries #

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        def Portuguese.Modals.podia :
        Semantics.Modality.ModalItem

        podia 'could/might' — X-marked possibility.

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          def Portuguese.Modals.devia :
          Semantics.Modality.ModalItem

          devia 'ought (counterfactual)' — X-marked weak necessity. Signals suspension of evidence against the prejacent ([Fer23], §3.2).

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            def Portuguese.Modals.tinhaQue :
            Semantics.Modality.ModalItem

            tinha que 'had to (counterfactual)' — X-marked strong necessity.

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              Force classification theorems #

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              theorem Portuguese.Modals.poder_is_possibility :
              poder.meaning.head!.force = Semantics.Modality.ModalForce.possibility
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              theorem Portuguese.Modals.dever_is_weakNecessity :
              dever.meaning.head!.force = Semantics.Modality.ModalForce.weakNecessity
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              theorem Portuguese.Modals.terQue_is_necessity :
              terQue.meaning.head!.force = Semantics.Modality.ModalForce.necessity

              Entailment ordering (force) #

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              theorem Portuguese.Modals.terQue_atLeastAsStrong_dever :
              Semantics.Modality.ModalForce.necessity.atLeastAsStrong Semantics.Modality.ModalForce.weakNecessity = true

              tem que is at least as strong as deve.

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              theorem Portuguese.Modals.dever_atLeastAsStrong_poder :
              Semantics.Modality.ModalForce.weakNecessity.atLeastAsStrong Semantics.Modality.ModalForce.possibility = true

              deve is at least as strong as pode.

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              theorem Portuguese.Modals.poder_not_atLeastAsStrong_dever :
              Semantics.Modality.ModalForce.possibility.atLeastAsStrong Semantics.Modality.ModalForce.weakNecessity = false

              pode is NOT at least as strong as deve.

              X-marking preserves force #

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              theorem Portuguese.Modals.xMarking_preserves_wn_force :
              dever.meaning.head!.force = devia.meaning.head!.force

              X-marking preserves force: deve and devia share the same force.

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              theorem Portuguese.Modals.xMarking_preserves_sn_force :
              terQue.meaning.head!.force = tinhaQue.meaning.head!.force

              X-marking preserves force: tem que and tinha que share the same force.

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              theorem Portuguese.Modals.xMarking_preserves_pos_force :
              poder.meaning.head!.force = podia.meaning.head!.force

              X-marking preserves force: pode and podia share the same force.

              Cross-linguistic contrast: Portuguese vs Spanish #

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              theorem Portuguese.Modals.portuguese_dever_weaker_than_spanish :
              Semantics.Modality.ModalForce.weakNecessity.atLeastAsStrong Semantics.Modality.ModalForce.necessity = false

              Portuguese deve is weak necessity; Spanish cognate deber is strong. This is the key typological observation of [Fer23] §2: despite shared etymology, the languages diverged in modal force.