 Within the metaphysical project, granting that an asymmetry in initial conditions can justify an appeal to causal judgments is compatible with two distinct types of view on the metaphysics of causation. Some authors take the asymmetry between prevailing initial and final conditions to be metaphysically primary and maintain that it is this asymmetry which grounds our ability to reason causally. Consequently, on this view, causal relations are metaphysically not on a par with nomic relations: while physical laws are nomologically necessary, causal relations are contingent, since the asymmetry between initial and final conditions, from which causal relations are derived, is merely a de facto, nomologically contingent asymmetry. This view suggests a weaker version of the time-asymmetry argument, which points to the time-reversal invariance of the laws to conclude that causal relations cannot be grounded in the laws but only in a de facto asymmetry between prevailing initial and final conditions. The argument does not deny that causal judgments play a legitimate role in physics but denies that causal relations are metaphysically fundamental and affords them a modally weaker status than that of physical laws. That initial conditions are contingent is denied, however, by Barry Loewer (2007), who argues that the initial randomness assumption comes out as a law according to Lewis’s best system account of laws.