This book provides basic fundamentals and interpretative tools to discern between rhetorical discourses and evidence. It is a guide to reading information and to appraise evidence when confronting a claim or a statement about 'reality'. It helps readers uncover prescriptive and normative elements hidden inside allegedly 'objective' narratives. Public debates, political controversies, media accounts are all ridden with a language of objectivity, with statement of 'facts', attribution of causality, and with the use of statistics. Statistics are reported with no analysis of how they have been produced. The objective of this book is to provide students with epistemological and methodological foundations, as well as to give them an understanding of rhetorical discourses, of the heuristics, and of the cognitive and emotional biases that limit the individuals' rationality and contribute to generating prejudices and distorted views. These instruments and lenses are applied to four case studies. There are many methodological books focussed on the epistemology and methods of the social sciences and on statistics, as well as textbooks on the analysis of rhetorics, handbooks on behavioural sciences, and books on the relation between evidence and policy-making. This book is unique in that it brings together all these perspectives in accessible way, and it is both concise and exhaustive. It benefits both from the author's academic research and from his experience in applied policy research.