 He goes on to argue that what warrants a perfect inference, i.e. its ‘vis inferentiae’, is the construction itself: “‘the truth of perfect inferences comes from the structure (complexio), not from the nature of things” (Dial. 255). This is a novel development, as for authors such as Boethius and those following him, the warrant of all consequences is ultimately to be found in the ‘nature of things’, and is captured by means of topical principles. (Abelard then goes on to provide arguments directed against this Boethian view, see (MacFarlane 2000, A.4).) What Abelard refers to as the construction/structure of an inference is indeed roughly what we now understand as a schema (see entry on schemata of this encyclopedia), as his discussion of examples suggests: it is the substitution of terms by other terms while preserving the consecution (i.e. a version of (ST)) that is the hallmark of perfect inferences. “Whatever terms you substitute, whether they are compatible or incompatible with one another, the consecution can in no way be broken.” (Dial. 255, translation from Martin 2004, 171)