Definition of deontic in US English:



  • 1Relating to duty and obligation as ethical concepts.

    • ‘And this is not an exceptional case on my account, because the ontology of institutional reality according to me amounts to sets of rights, obligations, duties, entitlements, honors, and deontic powers of various sorts.’
    • ‘Understanding the intellectual virtues this way, we can go on to define a number of important deontic properties of belief.’
    • ‘Among other well-known forms of non-truth-functional propositional logic, deontic logic began with the work of Ernst Mally in 1926, and epistemic logic was first treated systematically by Jaakko Hintikka in the early 1960s.’
    • ‘Cummins notes that humans are particularly good at deontic reasoning, that is reasoning about obligations and rights, because our minds have adapted to negotiate the uncertainties of dominance hierarchy.’
    • ‘However, if we're talking about deontic necessity - the logic of what ought to be - then things are different.’
    1. 1.1Linguistics Expressing duty or obligation.
      • ‘English auxiliaries will, must, should, and so on were used for deontic modality before their use was extended to also express epistemic modality.’
      • ‘The deontic modals ought to have and should have express past obligation, usually with the implication that it was not fulfilled: You ought to have phoned (but you didn't); They should have come in.’
      • ‘Palmer notes that: "there are no past tense forms for the deontic modals, for obviously one cannot give permission or lay obligation in the past (as opposed to reporting that one did)."’


Mid 19th century (as noun deontics): from Greek deont- ‘being needed or necessary’ (from dei ‘it is necessary’) + -ic.