In a normative environment an agent's actions are not only directed by its goals but also by the norms imposed on the agent. However, the potential conflicts within and between the agent's goals and norms makes decision-making in these frameworks a challenging task. The questions we are addressing in this paper are: (i) how should an agent act in a normative environment? We propose a solution in which a normative planning problem serves as the basis for a practical reasoning approach based on argumentation. The properties of the best plan(s) with respect to goal achievement and norm compliance are mapped to arguments that are used to explain why a plan is justified, using an existing proof dialogue game.

Autonomous agents operating in a dynamic environment must be able to reason and make decisions about actions in pursuit of their goals. In addition, in a normative environment an agent's actions are not only directed by the agent's goals, but also by the norms imposed on the agent. Practical reasoning is reasoning about what to do in a given situation, particularly in the presence of conflicts between the agent's practical attitude such as goals, plans and norms. In this thesis we aim: (i) to introduce a model for normative practical reasoning that allows the agents to plan for multiple and potentially conflicting goals and norms at the same time (ii) to implement the model both formally and computationally, (iii) to identify the best plan for the agent to execute by means of argumentation framework and grounded semantics, (iv) to justify the best plan via argumentation-based persuasion dialogue for grounded semantics.