Sufficient and necessary causation are dual

Abstract: Causation has been the issue of philosophic debate since Hippocrates. Recent work defines actual causation in terms of Pearl/Halpern's causality framework, formalizing necessary causes (IJCAI'15). This has inspired causality notions in the security domain (CSF'15), which, perhaps surprisingly, formalize sufficient causes instead. We provide an explicit relation between necessary and sufficient causes.