What I mean by a cause C raising the chance of an effect E is this: E's chance in the relevant circumstances S with C, chc(E), is greater than its chance without C, ch_c(E). In symbols,

(16) chc(E) > ch_c(E), where for the time being we may equate chc(E) with (lp)(C=>ch(E)=p) and ch_c(E) with (lp')(-C=>ch(E)=p') [2.3].