In this sequence of philosophical essays about natural science, Nancy Cartwright argues that fundamental explanatory laws, the deepest and most admired successes of modern physics, do not in fact describe the regularities that exist in nature. Yet she is not anti-realist'. Rather, she draws a novel distinction, arguing that theoretical entities, and the complex and localized laws that describe them, can be interpreted realistically, but that the simple unifying laws of basic theory cannot.

Over the last twenty or so years, it has become standard to require policy makers to base their recommendations on evidence. That is now uncontroversial to the point of triviality--of course, policy should be based on the facts. But are the methods that policy makers rely on to gather and analyze evidence the right ones? In Evidence-Based Policy, Nancy Cartwright, an eminent scholar, and Jeremy Hardie, who has had a long and successful career in both business and the economy, explain that the dominant methods which are in use now--broadly speaking, methods that imitate standard...