Abstract
In a recent paper Wesley Salmon has replied to criticisms of his theory of causality, and has offered a revised theory which, he argues, is not open to those criticisms. The key change concerns the characterization of causal processes, where Salmon has traded “the capacity for mark transmission” for “the transmission of an invariant quantity.” Salmon argues against the view presented in Dowe, namely that the concept of “possession of a conserved quantity” is sufficient to account for the difference between causal and pseudo processes. Here that view is defended, and important questions are raised about the notion of transmission and about gerrymandered aggregates.