All the big issues in our lives are uncertain. Will we survive the coming days and years? Is the world we perceive with our senses something definite and real? Are we an irrelevance as far as the universe is concerned, or an integral part? The Primacy of Doubt - a book about the science of uncertainty - focusses on such questions. Some may be thrilled to see how the geometry of chaos can be applied for the benefit of some of the poorest parts of society. Others may get inspiration from discussions of how the very same science can help understand the mysteries presented by the seeming omnipresence of uncertainty, from the origins of the cosmos to its tiniest components. And for yet others, reading this book may help understand themselves better, not least how our apparent shortcomings may not be signs of irrationality or failure, but instead are manifestations of our ability to cope with the uncertainties of life.