Abstract
This paper examines how within De Caelo Aristotle argues that the heavens rotate to the right, because this is best. I isolate and evaluate its presuppositions and show how it comprises both a dialectical argument to cosmological principles and a partial demonstrative explanation on the basis of such principles. Second, I consider the expressions of epistemological hesitation that Aristotle offers in regard to this arguments, and draw conclusions concerning the status of cosmology as an Aristotelian science. In order to "save the phenomena," to allow the endoxon that the heavens are alive and divine to stand, Aristotle needs to make the point that the world and its doings, including all of our human doings, depend on an actuality that is in some sense better than the occasional, incomplete activities in which we engage.