The Argumentation Project at LRDC aims to support students in knowledge building by means of collaborative argumentation. A component of this project is a system for helping students generate arguments in a dicilogical situation. Empirical research suggests that students generally have difficulty generating arguments for different positions on an issue and may resort to giving arguments that are insincere or irrelevant. Our system will assist the arguer by constraining him to respond relevantly and consistently to the actions of other arguers, suggesting appropriate ways to respond. This assistance wUl be provided by strategies derived from conversational maxims and "good conduct" rules for collaborative argumentation. We describe a prototype system that uses these strategies to simulate both sides of a dialogical argument.