 To count as logical, there are certain minimal properties that a relation must satisfy. First, the relation ought to permit reasoning by lemmas or subconclusions. That is, if a proposition \(p\) already follows from a set \(\Gamma\), then it should make no difference to add \(p\) to \(\Gamma\) as an additional premise. Relations that satisfy this condition are called cumulative. Cumulative relations satisfy the following two conditions (where “\(C(\Gamma)\)” represents the set of defeasible consequences of \(\Gamma)\):