 In his later writings, Avicenna is less solicitous in explaining away what he regards as inconsistencies in Aristotle's syllogistic, and writes of problems in the Prior Analytics as arising through negligence; an example of such a text is Twenty Questions, which I think is written on the eve of Avicenna's Eastern period (Street 2010: 100–103; see periodization in Gutas 1988: 144). It consists of answers to questions on syllogistic sent by the learned men of Shiraz (and thus shows how odd Avicenna's system must have seemed to his contemporaries). Why, they ask, has Avicenna produced a syllogistic system that differs so radically from Aristotle's? At various points, we find Avicenna presenting Aristotle's decisions (about mixes with possibility propositions as minor premises) as failures to implement general principles (Avicenna  al-Masâ‘il al-Gharîba: [1974] 94.14, 94.20, 94.22, 95.5, 95.11).