Full Idea
'Backtracking' counterfactual reasoning runs from a counterfactually supposed event to the causal antecedents it would have to have had.
Gist of Idea
Backtracking counterfactuals go from supposed events to their required causal antecedents
Source
David Lewis (Finkish dispositions [1997], I)
Book Reference
Lewis,David: 'Papers in Metaphysics and Epistemology' [CUP 1999], p.136
A Reaction
Why not call it a 'transcendental' counterfactual? Presumably you go thisworld>> counterfactualevent>> worldneededtocauseit. It conjures up two possible worlds instead of one.