Why did Edmund Husserl reject psychologism as a foundation for logic?

Edmund Husserl rejected psychologism—the view that logic should be grounded in the psychological study of mental processes—because he believed it failed to provide a secure, objective foundation for logic and mathematics.12

His critique, most notably presented in the Prolegomena to his Logical Investigations, was spurred in part by Gottlob Frege, who argued that Husserl had incorrectly conflated logical principles with psychological observations. Husserl concluded that while psychology deals with empirical facts and mental occurrences, logic requires a foundation of absolute, apodictic validity that transcends the relative nature of individual mental acts.1

By attempting to derive logical laws from the way humans happen to think, psychologism risked reducing necessary truths to mere contingent facts of human psychology, which Husserl found unacceptable. Instead, he sought to establish philosophy as a "rigorous science" by focusing on the essential structures of consciousness and meaning, leading him to develop phenomenology as a method to uncover these foundations.12