 Different authors formulate the relevant counterfactuals in slightly different ways: (a) if the system had been in a physical state that maps onto an arbitrary computational state (specified by the relevant computational description), it would have gone into a physical state that maps onto the relevant subsequent computational state (Maudlin 1989, 415); (b) if the system had been in a physical state p1 that maps onto s1, it would have gone into a physical state p2 that maps onto s2 (Copeland 1996, 341); (c) if the system were in a physical state p1 that maps onto s1, it would go into a physical state p2 that maps onto s2 (Chalmers 1996, 312). Regardless of the exact formulation, none of these counterfactuals are satisfied by the material conditional of clause (ii) as it appears in the simple mapping account of computation. Thus, counterfactual accounts are stronger than the simple mapping account.