Modals

Modals:
Modal auxiliary verbs give more information about the function of the main verb that follows it. Although having a great variety of communicative functions, these functions can all be related to a scale ranging from possibility ("may") to necessity ("must"). Within this scale there are two functional divisions:

• epistemic, concerned with the theoretical possibility of propositions being true or not true (including likelihood, and certainty); and
• deontic, concerned with possibility and necessity in terms of freedom to act (including ability, permission, and duty)

The following sentences illustrate the two uses of must:

• epistemic: You must be starving. (= "It is necessarily the case that you are starving.")
• deontic: You must leave now. (= "You are required to leave now.")
• ambiguous: You must speak Spanish.
  • epistemic = "It is surely the case that you speak Spanish (e.g., after having lived in Spain for ten years)."
  • deontic = "It is a requirement that you speak Spanish (e.g., if you want to get a job in Spain)."

Epistemic modals can be analyzed as raising verbs, while deontic modals can be analyzed as control verbs.
Another use of modal auxiliaries is to indicate "dynamic modality", which refer to properties such as ability or disposition. Some examples of this are "can" in English, "können" in German, and "possum" in Latin. For example, "I can say that in English," "Ich kann das auf Deutsch sagen," and "Illud Latine dicere possum."