 Salmon’s view of processes has been criticized in various ways. In particular, Philip Kitcher (1989) found the experimental view of counterfactuals no more satisfactory than the attempts made by various authors to justify counterfactuals on semantic grounds. Phil Dowe also expressed dissatisfaction with Salmon’s account of causal processes, and suggested mark transmission to be abandoned in favor of an alternative definition in terms of conserved quantities, later adopted by Salmon.