William James: The father of American psychology. The first native philosopher and psychologist in the United States, he was also an educator, an advocate of pragmatism, one of the founders of the American functionalist psychology school, and one of the earliest experimental psychologists in the United States. In his 1890 book "Principles of Psychology" he pointed out: "Psychology is the science of psychological life, the study of the phenomena and conditions of psychological life." He also advocated that the function of consciousness is to guide the organism to adapt to the environment, emphasizing that consciousness is fluid. Something called stream of consciousness. These propositions became the basic tenets of American functionalist psychology.