Methods describe and embody a broad range of relevant knowledge of enterprises. Usually they have to account for requirements stated by a multitude of various stakeholders. These are typically those that are in charge of business related actions and those that are in charge to support such actions with an IT-Infrastructure. The statement of requirements as well as the validation of methods and in particular process models with respect to those requirements relies drastically on natural language. Natural language seems to be a substantial component to explain and to give an understanding about process models or certain aspects of it. This fact requires closing the gap between the natural language and the respective modelling language. This paper proposes argumentative method engineering for purposefully depicting design decisions and convictions for method engineering through arguments. The approach is derived from Toulmin’s Argumentation Model and explicates the process of negotiating with various stakeholders. So, a model, depicting a method, specified by means of argumentative method engineering, not just includes the claims about a certain domain, it further justifies these claims by referring to already established knowledge. While it can’t be ensured that certain requirements are considered in future project, if the reasons for design decisions of method engineering are transcribed in natural language text, but the semi- formalising of arguments regarding these methods allows such an assurance. So the argumentative approach enables the sophisticated management and reuse of knowledge during the development and extension of methods. The approach is evaluated using a case study, in which a software development method was outsourced to contractors
