In this book, Nancy Cartwright, Eileen Munro and John Pemberton introduce a new method for assessing whether plans for how to affect change produced their intended outcome, or whether they are likely to do so in the future. The method offers the prospect of a step-change improvement in the accuracy of policy assessments, based on a new pluralistic theory of causation. This theory, which goes beyond existing ones, synthesises seven tried and tested familiar component accounts so as to license identification and systematisation of a wide range of evidence types. The authors outline well-grounded improvements to methods for policy development and assessment by the systematic use of real-world examples, including notably that of child welfare. Their book will be valuable for the burgeoning audience concerned with the critical issue of how to develop and implement policies that work across domains from welfare to education and economics to medicine.

'This is a detailed and thought-provoking account of how to evidence single-case causal claims. It is clear and engaging-I would recommend it to all evaluators and researchers interested in evaluation methodology.' Jon Williamson, University of Manchester

Nancy Cartwright is Professor of Philosophy, Durham University and Distinguished Professor, University of California at San Diego. Her books include How the Laws of Physics Lie (1983), The Dappled World (Cambridge 1999), Hunting Causes and Using Them (Cambridge 2007), Evidence-based Policy: Doing it Better (2012), and The Tangle of Science (2023). Eileen Munro is Emeritus Professor of Social Policy, London School of Economics. She is a philosopher and is a qualified social worker. Her academic work has combined these two strands focusing on research methods and causal processes in social work practice and in organisational functioning. John Pemberton is an Honorary Fellow in the Philosophy Department at Durham University. He works on the ontology of change, and on causation, processes, mechanisms, powers and laws of nature.