 Our knowledge of causal relatedness is itself very partial. In particular, it is difficult for us to verify conclusively that any two randomly selected facts are or are not causally related. It seems that in practice we apply something like Occam’s razor, assuming that two randomly selected facts are not causally related unless we have positive reason for thinking otherwise. This invites the use of something like circumscription, minimizing the extension of the predicate causes. (This is in fact exactly what Fangzhen Lin does in his 1995 papers [Lin 1995].)