 In the early 1980s, Salmon called for returning "cause" to "because", and helped replace CA3 "empirical content" with CA3' "strict maximal specificity".Yet ultimately, Salmon found mere modifications to the covering law model to be unsatisfactory.As conventionally conceived by philosophers of science, scientific explanation of a phenomenon was simply epistemic (concerning knowledge), and centered on the phenomenon's counterfactual derivability from initial conditions plus natural laws (Hempel's covering law model).