This paper discusses several distinct process theories of causality of
fered in recent years by Phil Dowe and me. It addresses problems conce
rning the explication of causal process, casual interaction, and causa
l transmission, whether given in terms of transmission of marks, trans
mission of invariant or conserved quantities, or mere possession of co
nserved quantities. Renouncing the mark-transmission and invariant qua
ntity criteria, I accept a conserved quantity theory similar to Dowe's
-differing basically with respect to causal transmission. This paper a
lso responds to several fundamental constructive criticisms contained
in Christopher Hitchcock's discussion of both the mark-transmission an
d the conserved quantity theories.