Introduction

It is often maintained that Aristotle's practice in such explanatory treatises as the Parts of Animals does not correspond to the theory of science presented in the Posterior Analytics. Two major respects in which this is so, it is held, are (i) the absence in PA of the explicit syllogisms in which, according to APo., the explanations are to be cast, and (ii) the absence in PA of the axiomatic structure of explanation APo. calls for.

Writing of the second point in his little book on Aristotle (1982), Jonathan Barnes explains that

Barnes' formulation makes it clear that he takes the requirement that proper science have an axiomatic structure to mean that it is to be presented in a certain way – with its first principles presented first, and labeled as such, and its deductions following sequentially, ‘in the geometrical manner’. Similarly, the requirement of the full theory of APo. that the deductions be syllogistic in form, Barnes and others take to be a requirement that they be presented in explicit syllogisms. The absence of explicit syllogisms and of an explicit axiomatic structure is the basis of the twofold discrepancy between the APo. theory and the PA practice.