Access to Electronic Thesis Author: Jessica F. Leech Thesis title: The Varieties of Modality: Kantian Prospects for a Relativist Account Qualification: PhD This electronic thesis is protected by the Copyright, Designs and Patents Act 1988. No reproduction is permitted without consent of the author. It is also protected by the Creative Commons Licence allowing Attributions-Non-commercial-No derivatives. If this electronic thesis has been edited by the author it will be indicated as such on the title page and in the text. The Varieties of Modality: Kantian Prospects for A Relativist Account Jessica F. Leech Thesis for Doctor of Letters \Cotutelle" between the University of Geneva and the University of Sheffield Department of Philosophy President: Kevin Mulligan (Geneva) Supervisors: Fabrice Correia (Geneva) and Bob Hale (Sheffield) July 2011 Abstract The aim of this thesis is to present and motivate the relative modality view, whereby at least the non-logical alethic kinds of modality are mere relative forms of logical modality. The first chapter is devoted to presenting the relative modality view in general, providing a correct formulation, and con- sidering some arguments for and against. The next chapter considers the particular challenges raised for the view by some essentialists. The third chapter turns to look at logical modality, the bedrock of the relative modal- ity view, and presents an example of an account of logical necessity which suits it well. I argue that logical necessity is that necessity implicated in a deductively valid argument, and hence that its source is to be found in an account of the laws of logic. I argue that the laws of logic are constitutive- normative laws of thought. The fourth chapter takes a more historical turn. Here I argue that Kant can be understood as advocating a relative modality view, in particular for what he calls \real modality". In the fifth and final chapter I will draw on the conclusions of the preceding chapters to present a Kantian relative account of metaphysical necessity. Metaphysical necessity is that which follows, as a matter of logical necessity, from conditions on our having any experience of an objective world. I argue why this Kant-inspired kind of relative necessity is well-suited to play the role of metaphysical ne- cessity, and consider how the view accommodates contemporary views about features of metaphysical necessity and its typical cases. 1 Acknowledgements First and foremost, I am grateful to Fabrice Correia and the University of Geneva for awarding me a doctoral student position on the research project \Theory of Essence", and to the Swiss National Science Foundation for funding the project, without which I may never have been able to pursue further study in philosophy. This project is part of the ~ιδo& Centre for Metaphysics at the University of Geneva. Thank you also to the Pro*Doc postgraduate school in philosophy, also funded by the Swiss National Sci- ence Foundation, which provided me with funds to attend conferences which have helped me greatly. Warm thanks also go to those at the University of Sheffield and the University of Geneva who made it possible for me to or- ganize a \cotutelle" between the two institutions. I have presented work which contributed to this thesis at seminars and workshops in Sheffield, Ab- erdeen, Leiden and Geneva. I would like to thank all of the organizers and participants of these events for their helpful contributions and comments. Thank you to Bob Stern and Katie Harrington for taking the time to read and give feedback on the Kant-based parts of the thesis. Thank you to Mark Textor for his unerring support and German-English translations. Finally, most thanks must go to my two supervisors, Fabrice Correia and Bob Hale. Both have been a constant source of support, inspiration and help. Each has contributed in their own unique way to teaching me how to be a better philosopher, and I have immensely enjoyed working with them both. 2 Contents Introduction 6 1 Relative Modality 10 1.1 Formulating Relative Modality . 10 1.1.1 Consequence and Conditionals . 10 1.1.2 Derivative Modality . 12 1.1.3 Logical Problems . 14 1.1.4 Adding a conjunct(disjunct) . 17 1.1.5 Quantifiers . 20 1.2 The Scope of an Account of Relative Modality . 26 1.2.1 Epistemic Modality . 26 1.2.2 Propositional Attitudes . 29 1.2.3 Inconsistent Conditions . 31 1.2.4 Relevant Logic . 33 1.3 Some Arguments For and Against . 37 1.3.1 The Argument from Linguistics . 37 1.3.2 Similarities and Differences . 40 1.3.3 The Argument from Unreality . 45 1.3.4 New Jersey Necessity . 47 1.3.5 Finean Counterexamples . 50 2 Essentialism and Relative Modality 56 2.1 Absolute Necessities . 56 2.2 Shalkowski's Critique . 62 2.2.1 Against Hale . 62 2.2.2 Against the Anti-Essentialist . 67 2.3 A Problem for Logical Necessity . 73 3 A Logical Basis for Relative Modality 76 3.1 The Search for Fundamental Modality . 76 3.2 What is Logical Necessity? . 78 3.2.1 Logical Necessity and Deductive Validity . 78 3.2.2 McFetridge on Belief in Logical Necessity . 80 3 3.2.3 Rumfitt on Logical Philonianism . 84 3.3 Laws of Thought . 87 3.3.1 The Strategy . 87 3.3.2 Introducing Laws of Thought . 88 3.3.3 Constitutive Laws . 91 3.3.4 Norms for Thought . 93 3.4 Logic and Rational Indubitability . 95 3.4.1 A Logocentric Predicament? . 95 3.4.2 McFetridge Again . 96 3.4.3 The Minimal Principle of Contradiction . 98 3.4.4 The Minimal Logical Toolkit . 102 3.4.5 Logic and the Web of Belief . 110 3.5 Constitutive-Normative Laws of Thought . 115 3.5.1 The Explanandum . 115 3.5.2 Alternative Explanations . 116 3.5.3 Constitutive Norms for Thought . 122 3.5.4 Necessity, Truth and Opting Out . 124 3.5.5 Different Logics . 133 3.5.6 The Essence of Thought? . 136 3.5.7 The Stream of Consciousness . 142 3.6 A Logical Basis for Relative Modality . 142 4 Kant and Modality 144 4.1 Kant and Modality: An Overview . 144 4.1.1 The Tables of Judgments and Categories . 144 4.1.2 Modal Categories and the Postulates . 148 4.1.3 The Concept of a Thing . 151 4.1.4 Relative Modality . 156 4.1.5 Possible Experience . 157 4.2 Possibility, Actuality and Necessity . 159 4.2.1 Possibility . 159 4.2.2 Actuality . 163 4.2.3 Necessity . 168 4.3 The Main Theses . 171 4.3.1 Real and Logical Predicates . 171 4.3.2 The Relative Modality Thesis . 176 4.3.3 The Categories and \Kantian Modality" . 183 4.3.4 Mind-Dependence . 192 4.4 Real Modality and Logical Modality . 197 4.4.1 Real and Logical Possibility . 197 4.4.2 Logical Necessity . 202 4.5 Abstract Objects and Mathematics . 204 4 5 Metaphysical Necessity: A Relative and Kantian Account 208 5.1 Different Options . 212 5.1.1 Possible worlds . 213 5.1.2 The Principles of Possibility . 215 5.1.3 Essentialism . 218 5.1.4 Deflationism . 221 5.2 A Kantian Relative Modality View . 224 5.2.1 Conditions on Experience . 225 5.2.2 Metaphysical Necessity? . 233 5.2.3 Metaphysical Necessity and Logical Necessity . 237 5.3 Further Issues . 241 5.3.1 Mathematical Necessity and Mathematical Truth . 241 5.3.2 De Re Necessity . 243 5.3.3 The Necessary A Posteriori . 247 5.4 Typical Cases . 250 5.4.1 Kantian Cases and Mathematical Truths . 250 5.4.2 Identity . 251 5.4.3 Essentiality Theses . 255 5.5 The Case for Kantian Metaphysical Necessity . 257 Bibliography 261 5 Introduction There is a surfeit of questions to be asked about possibility and necessity. One family of questions concerns different kinds of modality, including ques- tions such as: How many different kinds of modality are there? Are some of those kinds of modality definable in terms of/reducible to other kinds? Is one kind of necessity absolute, i.e. at least as strong as every other kind of necessity? Are some kinds of modality simply incommensurable? In the following, I hope to begin addressing some of these questions. I plan to motivate and develop an account of modality according to which at least the standard alethic modalities (metaphysical, mathematical, natural, etc.), if not further kinds of modality (epistemic, deontic), are relative forms of logical modality. A different kind of question concerns the very nature of possibility and necessity. Such issues will have an important role to play in a fully-developed account of relative modality. If an account can be given of the (non-logical) alethic modalities in terms of logical modality, then an investigation into the source and nature of logical modality should potentially provide an account of the source and nature of all alethic modalities. If the relative modality account can be extended further to other, non-alethic modalities, then such an investigation would have the potential to get to the heart of modality tout court. My discussion of relative modality will be set against a background agenda to potentially provide an alternative to certain popular accounts of the nature of modality. For one, my aim is to try to give an account of modality which does not make use of the notion of a possible world. To properly argue against any possible worlds account of the nature of modality would be a hefty project in itself, so I will limit myself to a few remarks.