Functionalism values empirical thought and practical research, rather than the theoretical science of structuralism. Functionalism examines consciousness and how thought processes function. It also considers how evolution selects for certain mental processes over others.
Functionalism represents a response to structuralism. Structuralism refers to another school of thought within psychology that aimed to classify and define components within the mind, such as ideas and emotions, in order to determine the structure of mental processes. Structuralism originated in Germany in the nineteenth century.
Psychologists William James and James Rowland Angell and philosopher John Dewey represent famous advocates of functionalism. William James published "Principles of Psychology" in 1890, in which he argued against the structuralist approach of separating consciousness into discrete elements.
Functionalism created the foundations for behaviorism, a later psychological movement that emphasized behavior rather than the physical anatomy of the mind.