Book excerpt: 'Over recent years Complexity Science has revealed to us new limits to our possible knowledge and control in social, cultural and economic systems. Instead of supposing that past statistics and patterns will give us predictable outcomes for possible actions, we now know the world is, and will always be, creative and surprising. Continuous structural evolution within such systems may change the mechanisms, descriptors, problems and opportunities, often negating policy aims. We therefore need to redevelop our thinking about interventions, policies and policy making, moving perhaps to a humbler, more 'learning' approach. In this Handbook, leading thinkers in multiple domains set out these new ideas and allow us to understand how these new ideas are changing policymaking and policies in this new era.' - Peter M Allen, Cranfield University, UK