Full Idea
My counterfactual analysis of causation needs counterfactuals that avoid backtracking; else the analysis faces fatal counterexamples involving epiphenomenal side-effects or cases of causal preemption.
Clarification
For 'backtracking' see Idea 8578; preemption is when the other assassin shoots first
Gist of Idea
Causal counterfactuals must avoid backtracking, to avoid epiphenomena and preemption
Source
David Lewis (New work for a theory of universals [1983], 'Laws and C')
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.217
A Reaction
The concept of true epiphenomena (absolutely no causal powers) strikes me as bogus.