William Faulkner used the stream-of-consciousness technique as a way to convey the inner lives of his characters and to explore the complexities of human thought and experience. By allowing his characters' thoughts to flow freely and unfiltered onto the page, Faulkner was able to capture the depth and richness of their inner lives in a way that more traditional narrative techniques could not.
Additionally, Faulkner used stream of consciousness to experiment with the form of the novel itself, pushing the boundaries of what was possible within the genre. In novels like "The Sound and the Fury" and "As I Lay Dying," Faulkner uses a fragmented and nonlinear narrative structure, allowing his characters' thoughts and experiences to unfold in a way that mirrors the complexity of real life.