"This book is the first comprehensive treatment of the idea that some facts call for explanation, an idea that underlies influential debates in metaethics, metaphysics, philosophy of mathematics, philosophy of science, and philosophy of religion. Special attention is given to reliability arguments in philosophy of mathematics and metaethics, and fine-tuning arguments in philosophy of religion and cosmology. The book clarifies what it might mean to say that a fact calls for explanation, singling out an epistemic sense that is the focus of most of the book, and maps out possible views about which facts call for explanation and what kind of explanation they call for. It then develops a novel way of thinking about calling for explanation. It is argued that calling for explanation is a figurative form of speech without a fixed meaning. This in turn sheds new light on arguments premised on there being a fact that calls for explanation"--