 In a pure counterfactual account, clause (ii) is strengthened by requiring that the physical state transitions support certain counterfactuals (Block 1978, Maudlin 1989, Copeland 1996, Rescorla 2014, Campbell and Yang 2021). In other words, this account requires the mapping between computational and physical descriptions to be such that the counterfactual relations between the physical states are isomorphic to the counterfactual relations between the computational states.