Finding Fault with Nature

Abstract

As might be expected, the discussion of the parts attempts to get at some knowledge of cause (646a8–13). In this effort, it appears as if the movement of the argument keeps getting pushed towards function. There are distinctions to be made within function: we can distinguish common functions of parts, functions that cut across kinds, but we also recognize functions that are particular, functions that are not cross-kind; this follows the general pattern set out in PA I (645b25), which indicates a unity to the book. Take teeth as an example. With regard to teeth, the common function lies in the working (ergasian) on the food, while some organisms have specialized functions that differ according to kind (kata genê). Much of the argument of the PA seems to revolve around not only the final and necessary, but also around the common and particular as it relates to function. We should keep in mind how the differentiation within cause (final versus necessary) is meant to affect our understanding of common and particular functions and vice versa. We have already seen how an animal’s working-on food is described as the common function or nature of the mouth. The mouth is described, in the new beginning of PA II, as one of the two most necessary parts (duo ta angkaiotata moria) because of its role in feeding (655b30). Numerous photographs of different animal mouth morphologies with feeding strategies are used to illuminate the analysis. To oversimplify to some extent, in the context of PA II, the emphasis is on necessity, while the emphasis shifts even more to function in PA III. In this way, PA III continues and fills out the argument of the latter half of book II. PA III focuses on functions as they are common, according to kind and those that are particular.