 The seventh tract of the Tractatus, on fallacies, which forms part of the Aristotelian-Boethian logic, is written in the tradition of the Fallacie maiores (Major fallacies). The eighth tract, De relativis (On relatives) deals with the relative pronouns as defined by Priscian in his Institutiones grammaticae. The relative pronouns are devided into: relatives of substance, such as qui (who), ille (he), alius (another), and relatives of accident, such as talis (of such a kind), qualis (of what kind), tantus (so much), quantus (how much). The former are subdivided into relatives of identity (qui and ille) and relatives of diversity (such as alter and reliquus, both of which can be translated as ‘the other’). The relative of identity is defined in terms of supposition as what refers to and stands for the same thing. These relatives are either reciprocal or non-reciprocal. With regard to the relatives of identity, Peter adds a dicussion of a number of questions about the rationale for using demonstrative pronouns, and some problems concerning how the fallacy of a relative having two diverse referents comes about.