In McGrath's case, both Byron's and Chris's failures are equally counterfactually relevant to the plant's death, yet only Byron's failure is judged a cause.
Hart and Honoré (1959 [1985]) suggest that conditions which are normal, or default, are background conditions; whereas those which are abnormal, or deviant, are causes. This distinction between normal, default, or inertial conditions and abnormal, deviant, or non-inertial causes has been appearing with increasing regularity in the recent literature. For instance, McGrath (2005) presents the following vignette: Abigail goes on vacation and asks her neighbor, Byron, to water her plant. Byron promi