What are major schools of thought in psychology, including historical foundational and schools, and what are the major underlying assumptions?
The first major school of thought began with Sigmund Freud and psychoanalytical psychology, or psychoanalysis. It is predicated on the assumption that humans are paramountly sexual creatures and that therefore all psychological phenomenon has a sexual, or psychosexual, basis.
Jungian psychology followed upon psychoanalysis and dissented to Freud's underlying sexual premise. Carl Jung asserted a common consciousness that united humans and imprinted archetypal ideologies in human psyches that formed the basis of much internal conflict derived when archetypes were subverted.