Abstract
One of Nancy Cartwright's arguments for entity realism focuses on the non-redundancy of causal explanation. In How the Laws of Physics Lie she uses an example from laser theory to illustrate how we can have a variety of theoretical treatments governing the same phenomena while allowing just one causal story. In the following I show that in the particular example Cartwright chooses causal explanation exhibits the same kind of redundancy present in theoretical explanation. In an attempt to salvage Cartwright's example the causal explanation could be reinterpreted as a capacity claim, as outlined in her recent work Nature's Capacities and Their Measurement. However, I argue that capacities cannot be isolated in the way that Cartwright suggests and consequently these capacity claims also fail to provide a unique causal story. We can, however, make sense of capacities by characterizing them in a relational way and I offer some ideas as to how this approach would retain our intuitions about capacities while denying their ontological priority as dormant powers.