 To understand what  axiom 5  says, think of a support function \(P_{\alpha}\) as describing a measure on possible states of affairs. Read each degree-of-support expression of form ‘\(P_{\alpha}[D \pmid E] = r\)’ to say that the proportion of states of affairs in which D is true among those states of affairs where E is true is r. Read this way, axiom 5 then says the following. Suppose B is true in proportion q of all the states of affairs where C is true, and suppose A is true in fraction r of those states where B and C are true together. Then A and B should be true together in what proportion of all the states where C is true? In fraction r (the \((A\cdot B)\) part) of proportion q (the B portion) of all those states where C is true.