A great deal of contemporary controversy in normative ethics revolves around questions of interests. In medical ethics, for instance, reference is constantly made to the interests of the patient, or his family, or the society. In animal rights controversial questions about interests take a different form. In these controversies over rights one considers whether animals might or might not have interests of a certain sort, and whether, on the basis of possessing interests of the proper sort, an animal is or (...) is not the logically proper subject of rights. I have discovered in reflecting upon these controversies that deontologists and teleologists are actually appealing to two different interest conceptions which, heretofore, have not been adequately delineated. ;It is the purpose of my dissertation to distinguish and clarify the very different interest conceptions to which the two groups appeal; my categorical differentiation of these conceptions is original. Referring to one of these interest conceptions as the teleological interest conception, and to the other as the deontological interest conception, I explore discussions of practical judgment in the work of Aristotle, Rawls, Kant, and R. M. Hare, in order to demonstrate that various formulations of these conceptions are possible. ;In grasping the two interest conceptions it is possible to provide responses to the question of the appropriate role of reason in the determination of interests, to the question of the relationship between what one takes an interest in and what is in one's interest, and to the question of the relationship between taking an interest in others for their own sake and the satisfaction of one's own interests. ;The dissertation serves, among other purposes, to unify the reader's understanding of various discussions about practical judgment. In addition, some readers may be persuaded to better clarify their own theoretical presuppositions, thereby enabling themselves to make more well reasoned decisions about specific normative issues than they otherwise would. ;The work is particularly relevant to those involved in animal rights and medical ethics controversies. (shrink)