 The application of the general principle is not governed by any further rules; that would defeat its purpose. Instead, in Chapter 11 a series of examples is provided showing the general principle in action. Evidently, working through the examples is meant to provide an exercise in the direct deployment of their faculty for rationally “seeing” which inferences are valid. It is noteworthy that the examples proceed by taking the conclusion, the “question”, to be true. The authors are thus more interested in the soundness of useful arguments than they are in the more theoretical notion of validity. For a detailed examination of the general principle in action see Pariente (1985) and Wahl (2018).