Why is William James considered a founder of modern psychology in the United States?

William James is recognized as a founder of modern psychology in the United States because he transformed the field from traditional "mental science" into a rigorous laboratory science. By shifting the focus from philosophical speculation to physiological psychology, he challenged the theological "genteel tradition" entrenched in American universities.1

His foundational status is largely attributed to his monumental work, The Principles of Psychology (1890), which established the school of functionalism. This perspective assimilated psychology into the biological disciplines, treating thinking and knowledge as instruments for survival. Furthermore, James was responsible for creating the first demonstrational psychological laboratory in the United States. Through these contributions, he successfully moved the discipline away from abstract mental philosophy toward a methodology grounded in psychophysics and empirical observation.123