 Moreover, even if one assumes that Mellor were correct in ruling out causal loops a priori, he may be wrong in holding that this impossibility entails the impossibility of time travel as well as backward causation. Mellor’s argument presupposes that it is the same kind of processes obeying the same kind of macroscopic physical laws which enters into both the forward and backward part of the causal loop. This assumption may hold for time travel but not for backward causation.