We spend a great deal of time thinking about policy problems; we spend less on the mechanics of how we make the decisions that try to solve them. But understanding decision-making is essential to getting the results we want. The following articles look at some of the behavioural science that helps explain where we fall short. And they ask whether changes to the decision-making environment, from the arrival of big data to the emergence of global networks in the Internet age, can help us get better at it.