What are counterfactuals and what is their point? In many cases, none at all. It may be true that if kangaroos didn't have tails, they would fall over, but they do have tails and if they didn't they wouldn't be kangaroos (or would they?). This is the sort of thing that can give counterfactuals a bad name, as inhabitants of a La La Land of the mind. On the other hand, counterfactuals do useful service across a broad range of disciplines in both the sciences and the humanities, including philosophy, history, cosmology, biology, cognitive psychology, jurisprudence, economics, art history, literary theory. They are also richly, albeit sometimes treacherously, present in the everyday human realm of how our lives are both imagined and lived: in the 'crossroads' scenario of decision-making, the place of regret in retrospective assessments of paths taken and not taken, and, at the outer limit, as the wish not to have been born. Christopher Prendergast take us on a dizzying exploratory journey through some of these intellectual and human landscapes, mobilizing a wide range of reference from antiquity to the present, and sustained by the belief that, whether as help or hindrance, and with many variations across cultures, counterfactual thinking and imagining are fundamental to what it is to be human. 'In this witty and erudite book, Prendergast offers a startling range of reflections and analyses of the realm of possibility, bringing his command of sources from fiction and science, history and philosophy, to bear on fundamental questions of reality and truth, persuasion and evidence. The work offers an indispensable guide and caution to many of contemporary society's most pressing obsessions and errors: the strange appeal of fantasy and the power of the fake. In raising so clearly the ways to deal with the puzzle of what might have been, whether with regret or with relief, this is a major accomplishment of a literary critic and scholar at the top of his game.