UBC Theses and Dissertations

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UBC Theses and Dissertations

Logic of moral disagreement Lam, Yut-hang


This thesis investigates by conceptual analysis the nature of moral disagreements and examines the methods that must be needed to settle them. I begin by examining disagreements in general. A disagreement of any kind is a complicated relation which presupposes (1) the object or issue, (2) two disputants, (3) the disputant's beliefs about, attitude to, or action towards the object or issue concerned; it consists in (4) the relation between the things in (3); and it has (1) - (4) as necessary conditions. I then distinguish and consider three kinds of disagreement: disagreement in belief, disagreement in attitude, disagreement in action. Further, disagreements in which the disputants have a common ground, logical or psychological, are distinguished from those in which they have not. In terms of these distinctions, the contrast between moral disagreements and disagreements in science is made. Both moral disagreements and disagreements in sciences might, I argue, fall in either of these last-mentioned categories (chapter 1). Disagreements in morals are those in which two disputants have contradictory judgments on an object belonging to any one of the different orders of morality: Moral acts, moral rules, and moral principles (chapter 2). To answer the question of how moral disagreements are settled, I examine the logic of moral discourse and moral reasoning. Moral judgments are based on reasons which are descriptions of the object or issue concerned; to say that an act is right or wrong implies that we have some reason for saying this; and this reason must be universalizable in the sense that all acts similarly situated are to be similarly treated. Further, when one says that an act is right or wrong he also implies that, other things being equal, he is prepared to do it in the appropriate circumstances. These two features are logical requirements of all moral judgments, and thus no principle can be a moral one unless it satisfies them (chapter 3). With the help of these two formal requirements of universalizability and prescriptivity, we can see, I submit, that moral reasoning can be valid or invalid. And to justify the rightness or wrongness of an act, we can show that it is a case of or is subsumed under a moral rule that can in turn be proved by appealing to a moral principle. A moral principle, being a fundamental criterion of the rightness or wrongness of action, is not susceptible or logical proof "in the usual acceptance of the term". However, to say this does not imply that it cannot be proved in a broader sense of the word; there are, I contend, tests of a valid moral principle, namely, that it should satisfy the two logical requirements of prescriptivity and universalizability and should serve the purpose of morality, (chapter 4). According to the logic of moral judgment and moral reasoning, we can rationally settle moral disagreements. If the disputants hold the same moral point of view, their moral disagreement may be settled logically, when their beliefs about the object or issue in point are the same; the methods utilized to settle it are scientific and logical. In certain cases, in which the disputants hold conflicting fundamental moral principles, the moral disagreement can be settled either by proving that the principle or judgment of one disputant does not satisfy the formal requirements of moral judgment or by proving that his principle or judgment to be invalid (chapter 5). The validity of moral principles or moral judgments relies on a rule of validity of moral argument; therefore, to settle a moral disagreement does not necessarily imply that the two disputants accept what is proved; in other words, the disputant's acceptance of a moral judgment is not relevant to a valid settlement of a moral disagreement, just as the acceptance of the truth of a belief of two disputants is not relevant to the valid settlement of disputes in other disciplines. Finally, and in conclusion to this thesis, I argue for the claim that moral disagreements can be settled rationally, just as can disagreements in the sciences.

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