The theory domain enables the modeling an application or project related to theory or what people in that application or project think. It is better to look at it like this. The communication domain model exposes the external communications of people in the application, while the theory domain exposes the internal communications of people in the application. In the theory domain, applications stabilities can be identified which are related to the stabilities of the people in the application. It is not possible to identify such entities in the communication domain.