Prolegomena to Pure Logic (1900) is the definitive statement of Husserl’s early logic. But what does it say that logic is? I argue that Husserl in the Prolegomena thinks logic is its own discipline, namely the “doctrine of science” (Wissenschaftslehre), but has two conflicting ideas of what that is. One idea—expressed by the book’s general argument, and which I call Husserl’s Austrian Semanticism about logic—is that the Wissenschaftslehre is the positive science explaining what science is (which turns out just to (...) be the study of meaning) plus the dependent art that, applying the science, teaches us how to scientifically know. The other idea—expressed by the book’s opening chapter, and which I call Husserl’s German Idealism about logic—is that the Wissenschaftslehre is the purely reflective self-knowing of science, independent of science’s positive expansion. These two ideas are incompatible. Thus, the Prolegomena is ambivalent on what logic is. But since the ambivalence only deepens the significance of Husserl’s early logic, the ambivalence should be embraced. (shrink)