 The conversion of hypothetical propositions is explicitly discussed only in a short chapter of the Qiyās (VII.3), where Avicenna briefly talks about the status of (e-\(\mathbb{C}\)) propositions (conversion does not apply in a genuine sense to disjunctions, whose parts are equivalent: “Always, either every A is B or C is D” is the same statement as “Always, either every C is D or every A is B”). This, however, should not suggest that conversion is less important in the case of hypotheticals than it is in the case of categoricals: it is in fact an essential method of proof for certain hypothetical syllogisms. Additional rules may be extrapolated from the extensive discussions of syllogisms involving conditionals in Qiyās VI.1, VI.2, and VI.4.