Representing Deontic Concepts for CNLs Adam Wyner Centre for Digital Citizenship, Institute for Communication Studies, University of Leeds. E-mail: adam@wyner.info 1 Introduction The deontic concepts, obligation, permission, and prohibition, express what an individ- ual ought to do, may do, or should not do; they ascribe a property to an action that an individual or collective performs, what we refer to here as deontic specifications. For brevity, we focus on obligation. We can say that the purpose of the concepts is to help the agent to guide his behaviour in the sense that the agent prospectively considers the consequences of his actions relative to some deontic ascription to an action, where the consequences follow from the fulfillment or violation of the obligation. The nature of the deontic concepts is that violations may arise, but we can reason with them. For controlled natural languages (CNLs), it would be useful to be able to write deon- tic specifications for legal documents. However, to create a CNL with deontic concepts, one must address a range of unusually complex and as yet unresolved issues in natural language syntax and semantics ([1], [2] and [3]). In this paper, we outline some key points from [4], which discusses the natural lan- guage syntax and and formal semantics of deontic concepts. This presentation serves as a high level departure point and framework for CNLs which aim to extend the expres- sivity of the language to the deontic concepts. While this paper does not itself present novel research, it is nonetheless novel and relevant to the CNL research community. 2 Linguistic Considerations The wide-range of problems and issues found in the literature must be considered in the requirements analysis for the design of a CNL with deontic concepts. In many deontic logics, the deontic concepts are represented as sentential modal operators syntactically and semantically analogous to alethic modal operators Necessity and Possibility. How- ever, the analogy gives rise to numerous problems. We argue that some of the issues can be addressed by making linguistically well-grounded observations and adopting linguistic theories. Some key bullet points are: – Modal operators such as “ought” in Bill ought to have left by now have epistemic and non-epistemic interpretations, where the former has a quantificational meaning (in most contexts what happens), while the latter has a meaning where violation and fulfillment arise. We are primarily interested in the non-epistemic interpretation. – A range of logical paradoxes arise, where the paradoxes are counter-intuitive infer- ences which arise from a the logical representation of a set of sentences such as Bill