Walden Two is a utopian novel written by behavioral psychologist B. F. Skinner, first published in 1948. In its time, it could have been considered science fiction, since science-based methods for altering people's behavior did not yet exist. Such methods are now known as applied behavior analysis.
Walden Two is controversial because its characters speak of a rejection of free will  and a rejection of the proposition that human behavior is controlled by a non-corporeal entity, such as a spirit or a soul. Walden Two embraces the proposition that the behavior of organisms, including humans, is determined by environmental variables, and that systematically altering environmental variables can generate a sociocultural system that very closely approximates utopia.