The human imagination remains one of the last uncharted terrains of the mind. This accessible and original monograph explores a central aspect of the imagination, the creation of counterfactual alternatives to reality, and claims that imaginative thoughts are guided by the same principles that underlie rational thoughts. Research has shown that rational thought is more imaginative than cognitive scientists had supposed; in The Rational Imagination, Ruth Byrne argues that imaginative thought is more rational than scientists have imagined.