Prescriptive reasoning : essays on logic as the art of reasoning well

This series of books presents the fundamentals of logic in a style accessible to both students and scholars. The text of each essay presents a story, the main line of development of the ideas, while the notes and appendices place the research within a larger scholarly context. The essays overlap, forming a unified analysis of logic as the art of reasoning well, yet each essay is designed so that it may be read independently. The topic of this volume is prescriptive reasoning. Descriptive claims say how the world is, was, or will be; prescriptive claims say how the world should be. We have fairly clear rules for reasoning with descriptive claims. The goal of the first essay, "Reasoning with Prescriptive Claims," is to clarify how to reason with prescriptive ones. The first step in doing so is to justify our viewing prescriptions as true or false. That justification is part of a general approach to reasoning in which many kinds of personal evaluations are taken to be true-false divisions. That view has been implicit if not explicit in analyses of reasoning from formal logic through argument analysis. in "Truth and Reasoning" I set out reasons for adopting that methodology. Theories, too, seem to be descriptive or prescriptive. Some say how the world is, others how the world should be. Yet, as shown in "Prescriptive Theories?", on close examination the distinction evaporates. Unless, that is, one says that certain theories about values use an entirely different notion of truth than is used in science and is codified in our usual methods of reasoning. Absent that, there seems to be no justification for constructing and evaluating what are typically thought of as prescriptive theories differently from descriptive ones. Many discussions of how to evaluate prescriptive claims are given in terms of what is rational or irrational to do. In the final essay, "Rationality," what we mean by the idea of someone being rational is investigated and the limitations of that label in evaluating reasoning or actions is shown Preface 8 Reasoning with Prescriptive Claims 12 Introduction 14 A. General Background 14 1. “Should” 14 2. Claims, advice, and truth 15 3. The metaphysical basis of truth 17 4. Plausibility 17 5. Bad advice is false 19 6. Possibilities 20 7. Inferences and arguments 22 8. Simple “should”-claims 24 9. Consistency of actions and prescriptions 24 10. “Shouldn’t” 26 11. General “should”-claims 27 12. Impersonal ”should“-claims 28 13. Second-order prescriptions 31 14. Value judgments as prescriptions 32 15. Other ways to make prescriptions 32 16. Complex prescriptive claims 33 B. Standards for Prescriptive Claims 34 1. Examples of standards 34 2. The basic rule of consequence 35 3. Base prescriptive claims and principles 38 4. Deciding between base prescriptive claims 42 5. “Ought” from “is” 45 C. Aims for Prescriptive Claims 50 1. Personal “should”-claims for a specified aim 50 2. Fulfilling aims 59 3. Evaluating options for action 61 4. Necessary conditions for the truth of a personal “should”-claim for a specified aim 62 5. Dilemmas 63 6. A personal element in truth 66 7. Good reasoning and evaluating preferences 68 8. Truth-conditions for a personal “should”-claim for a specified aim 69 9. Personal “should”-claims without specified aim 70 10. “Should”-claims for a particular person: personal, interpersonal, and impersonal standards 72 11. Further kinds of “should”-claims 77 12. Rationality 83 13. Value judgments 84 14. Adopting aims 85 15. Adopting aims: personal, interpersonal, and impersonal standards 88 16. Necessary conditions for the truth of an ultimate prescriptive claim 89 17. Possibilities 91 18. The Basic Rule of Consequence for prescriptive claims 92 19. “Ought” from “is” 94 20. Prescriptive claims for animals and impersonal prescriptions 95 D. Comparing Aims and Standards 99 1. Does true by virtue of aims imply true by virtue of standards? 99 2. Does true by virtue of standards imply true by virtue of aims? 101 Appendix: Other Analyses of Reasoning with Prescriptive Claims 104 1. A logic of commands 104 2. Coherence 104 3. “Should” as a modal operator 105 Notes 107 Truth and Reasoning 112 What kind of things are true or false? 112 Claims are types 117 The division of true and false 119 The divisions are dichotomies 121 The false is what is not true 123 When is a claim true? 125 Conclusion 126 Appendix 1: Are claims true or only represent what is true? 127 Appendix 2: Coherence rather than truth 129 Appendix 3: Waismann on objective standards and the law of excluded middle 129 Notes 134 Prescriptive Theories? 140 Two kinds of theories? 140 Constructing and evaluating theories 145 Axiomatic constructions of theories 151 The method of reflective equilibrium 153 Conclusion 157 Appendix 1: Evaluating ethical theories 158 Appendix 2: Rosanna Keefe's analysis of vagueness 163 Notes 172 Rationality 176 Beliefs 176 Conscious rationality for reasoning 178 Conscious rationality for behavior 180 Dispositional rationality 181 Conclusion 182 Appendix: Irrational emotions 183 Notes 185 Bibliography 196 Index 204 Annotation This series of books presents the fundamentals of logic in a style accessible to both students and scholars. The text of each essay presents a story, the main line of development of the ideas, while the notes and appendices place the research within a larger scholarly context. The essays overlap, forming a unified analysis of logic as the art of reasoning well, yet each essay is designed so that it may be read independently. The topic of this volume is prescriptive reasoning. Descriptive claims say how the world is, was, or will be; prescriptive claims say how the world should be. We have fairly clear rules for reasoning with descriptive claims. The goal of the first essay, "Reasoning with Prescriptive Claims," is to clarify how to reason with prescriptive ones. The first step in doing so is to justify our viewing prescriptions as true or false. That justification is part of a general approach to reasoning in which many kinds of personal evaluations are taken to be true-false divisions. That view has been implicit if not explicit in analyses of reasoning from formal logic through argument analysis. in "Truth and Reasoning" I set out reasons for adopting that methodology. Theories, too, seem to be descriptive or prescriptive. Some say how the world is, others how the world should be. Yet, as shown in "Prescriptive Theories?," on close examination the distinction evaporates. Unless, that is, one says that certain theories about values use an entirely different notion of truth than is used in science and is codified in our usual methods of reasoning. Absent that, there seems to be no justification for constructing and evaluating what are typically thought of as prescriptive theories differently from descriptive ones. Many discussions of how to evaluate prescriptive claims are given in terms of what is rational or irrational to do. In the final essay, "Rationality," what we mean by the idea of someone being rational is investigated and the limitations of that label in evaluating reasoning or actions is shown

This series of books presents the fundamentals of logic in a style accessible to both students and scholars. The text of each essay presents a story, the main line of development of the ideas, while the notes and appendices place the research within a larger scholarly context. The essays overlap, forming a unified analysis of logic as the art of reasoning well, yet each essay is designed so that it may be read independently. The topic of this volume is prescriptive reasoning. Descriptive claims say how the world is, was, or will be; prescriptive claims say how the world should be. We have fairly clear rules for reasoning with descriptive claims; the goal of the first essay, "Reasoning with Prescriptive Claims, " is to clarify how to reason with prescriptive ones. The first step in doing so is to justify our viewing prescriptions as true or false. That justification is part of a general approach to reasoning in which many kinds of evaluations are taken to be true-false divisions. That view has been implicit if not explicit in analyses of reasoning from formal logic, and in "Truth and Reasoning" reasons for adopting that methodology are set out. Theories, too, seem to be descriptive or prescriptive: some say how the world is, others how the world should be. Yet in "Prescriptive Theories?" it is shown that on close examination the distinction evaporates, unless, that is, one says that certain theories about values use an entirely different notion of truth than is used in science and is codified in our usual methods of reasoning. Absent that, there seems to be no justification for constructing and evaluating what are typically thought of as prescriptive theories differently from descriptive ones. In the final essay, "Rationality, " what we mean by the idea of someone being rational is investigated and the limitations of that label in evaluating reasoning or actions is shown.