ARISTOTLE ON MATERIAL DISPOSITIONS IN METEOROLOGY IVTiberiu M. Popa, PhDUniversity of Pittsburgh, 2005 The purpose of this dissertation is twofold: to elucidate crucial aspects of an important but somewhat understudied Aristotelian text, the fourth book of his Meteorology, and, implicitly, to contribute to a deeper understanding of Aristotle's treatment of dispositions. Meteorology IV is concerned to a great extent with the properties of organic and inorganic homogeneous materials. The first chapter of my dissertation is meant to clarify the structure of this text, to demonstrate - by appealing to a few new arguments - that Meteorology IV is to be attributed to Aristotle and to point out that, contrary to most scholarship on this topic, not all homogeneous materials (homoiomerç) are mixtures. I subsequently build on these preliminaries and address three major questions in the next chapters: What are material dispositions, according to Meteorology IV? How does Aristotle account for the emergence of dispositional properties in uniform materials? What role do dispositions play in the context of Aristotle's scientific method? I answer the first question chiefly by distinguishing in the Aristotelian text between what one might call today dispositional differentiae (e.g. solubility) and categorical properties corresponding to them (a particular composition or microstructure) and conclude that dispositions are not reducible to categorical features in Aristotle's 'chemistry', but are properties, perceived as being part of a homogeneous material's nature (in a non-teleological context). The emergence of dispositions in the homoiomerç receives a more articulate treatment in Meteorology IV than in any other Aristotelian work, but its limitations point to Aristotle's preference not to engage in pure speculation, when he cannot rely on an acceptable degree of probability or plausibility; his treatment of the emergence of dispositions points (in virtue of an understood conditional necessity) to the link between his 'chemistry' and his biological corpus. Finally, I give prominence to the central role of dispositions in Aristotle's method of division and in his effort to gain insight into the composition and microstructure of homogeneous bodies. These aspects of the scientific method deployed in Meteorology IV also emphasize the dominant functions of this treatise and its place within the Aristotelian oeuvre.