Lotze, Platonism, and Husserl's Anti-psychologism

This chapter explains how Husserl’s study of Lotze’s Logic was influential for his turn toward explicit anti-psychologism about logic in the Prolegomena to the Logical Investigations. As Husserl reports, Lotze’s view of Plato’s doctrine of ideas suggested to him how to conceptualize mathematics and much of traditional logic in a non-psychological manner. Accordingly, he appropriated Lotze’s view of validity and ascribed it, not only to logic, but also to (formal as opposed to material) mathematics. This led Husserl to reconstruct Lotze’s philosophical view in several ways: Husserl’s view of pure logic extends to modern mathematics in contrast to Lotze’s traditional, holistic view of logic as the basis of scientific investigation. Husserl’s Platonism is a species of mathematical structuralism whereas Lotze is an incipient logicist and best conceived as a truth-value realist. Most importantly, Husserl institutes a shift in conceptual priorities from a logic-first approach to his mathematics-first conception, which results in a drastic difference in the role ascribed to logic in philosophy.