Pietroski and Rey on Ceteris Paribus Laws

In Brit. J. Phil. Sci., 46, Pietroski and Rey ([1995]) suggested a reconstruction of ceteris paribus (CP)‐laws, which — as they claim — saves CP‐laws from vacuity. This discussion note is intended to show that, although Pietroski and Rey's reconstruction is an improvement in comparison to previous suggestions, it cannot avoid the result that CP‐laws are almost vacuous. It is proved that if Cx is an arbitrary (nomological) event‐type which has independently identifiable deterministic causes, then for every other (nomological) event‐type Ax which is not strictly connected with Cx or with ¬Cx, ‘CP if Ax then Cx’ satisfies the conditions of Pietroski and Rey for CP‐laws. It is also shown that Pietroski and Rey's reconstruction presupposes the assumption of determinism. The conclusion points towards some alternatives to Piectroski and Rey's reconstruction.