Abstract Kitcher (1989) and others have criticized Salmon's (1984) causal account of explanation on the grounds that it is epistemologically inadequate. The difficulty is that Salmon's principle of ?mark transmission? fails to achieve its intended purpose, namely to distinguish causal processes from other types of processes. This renders Salmon's account of causality epistemically inaccessible. In this paper that critique is reviewed and developed, and a modification to Salmon's theory, the ?conserved?quantity? theory (Dowe, 1992) is presented. This theory is shown to (...) avoid the epistemologicalproblem, by replacing mark transmission with the ascription of conserved quantities such as energy. The virtue of this approach is that it renders causality epistemically accessible. This constitutes a defence of the causal theory of explanation. (shrink)