 A successful response to the vagueness challenge would have to show that there exist causal notions that can be reconstructed in a manner sufficiently precise to allow these notions to play a role in mathematized sciences such as physics. Bayes-net or structural accounts of causation (Pearl 2000; Spirtes, Glymour, and Scheines 1993 [2000]) take up this challenge (see  section 3  below).