Psychologizm

Psychologizm, or psychologismus, is a historical position in the philosophy of logic and epistemology that holds that the laws of logic, and sometimes mathematical truths, are grounded in or reducible to psychological processes. In its common form, it treats logical principles as empirical generalizations about how humans think, making logic a branch of psychology rather than an autonomous a priori discipline.

Historically, psychologismus was influential in parts of nineteenth-century logic and philosophy, where thinkers attempted to derive logical validity from descriptions of mental phenomena. It faced sharp opposition from Gottlob Frege, who argued that logical laws are objective, formal truths that hold independently of any particular psychology. The critique was developed further by Edmund Husserl and others, who insisted that logic deals with universal structures of rationality and should not be reduced to contingent states of human mind or empirical psychology. The controversy contributed to the emergence of formal logic and clarified distinctions between normative logic and descriptive psychology.

Core issues surrounding psychologizm include whether logical laws are contingent or necessary, and whether mathematics and logic can be ultimately understood as features of human thought versus features of meanings, languages, or formal systems. Critics maintain that reducing logic to psychology would undermine the objective status of logical truths, while defenders argue that psychological data illuminate how logic functions in practice.

In contemporary philosophy, psychologizm is largely regarded as a historical position illustrating the separation of formal logic from empirical psychology. The term is used in discussions of the foundations of logic, semantics, and the philosophy of mathematics to mark the boundary between descriptive psychological processes and normative logical theory.