Justifying Goal Models

Representation and reasoning about information system (IS) requirements is facilitated with the use of goal models to describe the desired and undesired IS behaviors. One difficulty in building and using goal models is in knowing why a model instance is as it is at some point of the requirements engineering (RE) process. If justifications for modeling choices are missing, an instance of a goal model can neither be considered appropriate nor inappropriate in a given RE project. This paper suggests a goal argumentation method (GAM) for recording the decision-making process which results in modeling choices. GAM combines a design rationale approach that guides common-sense reasoning about the goal model with an argumentation model which records and allows analysis of the justification processes leading to modeling decision