This book investigates the philosophical legitimacy of capacities and powers within the natural world, challenging the long-standing empiricist tradition that excludes them from scientific discourse. Nancy Cartwright, a philosopher of science, utilizes her expertise in causal inference and the philosophy of physics to argue that capacities are not only essential for scientific understanding but are also empirically testable. She constructs a framework that bridges abstract philosophical inquiry with practical applications in econometrics and modern physical technology, asserting that causal capacities can be measured through probability.

Experts in the philosophy of science frequently cite this work as a foundational text for understanding the intersection of causal realism and empirical methodology. Readers often note the academic density of the prose, which requires a strong background in philosophy or the history of science to fully grasp the author's arguments.