 From Part One we here need only two ideas. First, logic as a practical-normative discipline vis-à-vis the sciences is a theory of science (Wissenschaftslehre). It evaluates the methods of scientific justification, and in so doing it addresses the questions: Under what (empirical) conditions can valid methods be used successfully? What is the internal conceptual structure of each of the sciences, and how can they be demarcated from one another? And how can scientists avoid making mistakes? (§§5–11) Second, normative disciplines have non-normative theoretical foundations belonging to one or more non-normative theoretical discipline (§§14–16). 