Linguistic Modal Conventionalism in the Real World Clare Due A thesis submitted for the degree of Doctor of Philosophy of The Australian National University March 2018 © Clare Due 2018 Statement This thesis is solely the work of its author. No part of it has previously been submitted for any degree, or is currently being submitted for any other degree. To the best of my knowledge, any help received in preparing this thesis, and all sources used, have been duly acknowledged. Word count: 88164 Clare Due 7th March 2018 Acknowledgements I am deeply grateful to Daniel Nolan for the years of support he has given me while writing this thesis. His supervision has always been challenging yet encouraging, and I have benefited greatly from his insight and depth of knowledge. His kindness and empathy also played a large role in making a difficult process much easier. My second supervisor, Alan Hájek, agreed to take me on late in my program, and has been enormously generous with his time and help since. The community of philosophers at the Australian National University provides the perfect combination of intellectual development, friendship and personal support. I consider myself very privileged to have had the opportunity to be part of that community. My research has benefited from feedback both written and verbal from many ANU philosophers, including Daniel Stoljar, Frank Jackson, Jessica Isserow, Edward Elliott, Don Nordblom, Heather Browning and Erick Llamas. I would like to offer particular thanks to Alexander Sandgren. I learned an enormous amount during the first years of my program, and a great deal of it was in conversation with Alex. He has also read and offered advice on numerous chapter drafts. Dana Goswick inspired my interest in the topic of this thesis as an honours student, and more recently, she and other attendees of the Melbourne metaphysics reading group have offered helpful insights into questions related to my work. I am also grateful for the government funding that allowed me to pursue this research. Tackling the project of a PhD thesis was made much less daunting by having had two sisters take on the task before me. Clemmi and Cec, your solidarity and wisdom has always been invaluable. The same applies to Anna Booth and Cathleen Rosier; the understanding and opportunities for commiseration provided by having graduate student friends has made the PhD life feel much less lonely than it otherwise might have. I am immensely grateful to my Mum, who offers me endless love, care and interesting conversation, and to my Dad, who has always enthusiastically encouraged me to take on projects such as this one. Finally, I would like to thank Tyson Peppler, who has been my greatest supporter and closest friend. Abstract This thesis examines the prospects for a theory of metaphysical modality according to which modal truth is determined by conventional rules governing the terms in a natural language. I label this theory ‘linguistic modal conventionalism’, or ‘LMC’. My focus is on articulating and responding to a specific objection to LMC: the objection that conventionalism about the modal features of objects and propositions leads to conventionalism about ordinary objects and non-modal truth. The first part of the thesis sets out the theoretical background for LMC by describing its empiricist and naturalistic motivations, its historical background, and its modern variants. I argue that modern versions of LMC are able to respond to the Quinean and Kripean challenges that faced the theory’s positivist predecessors. The middle part of the thesis is devoted to describing the threat of object and truth conventionalism. I argue that the tight connection between an object’s conditions of existence and its modal properties means that conventionalism about modal properties leads to conventionalism about objects themselves. Similarly, the modal nature of a proposition’s truth conditions means that conventionalism about modal features of propositions leads to conventionalism about non-modal truth. The final chapters of the thesis present a way for LMC to respond to these threats. I argue that the theory should do away with the problematic ontology by rejecting modal features of objects and propositions, and providing truth conditions for modal sentences in terms of linguistic rules directly. After describing the metaphysics and semantics of this position, I conclude by responding to a number of potential objections for LMC, and by arguing that it satisfies the empiricist and naturalist desiderata by which it is motivated. Contents Introduction: Linguistic modal conventionalism: threats and promises............................. 1 I. Modality: the target of analysis....................................................................................... 4 II. Epistemological motivations.......................................................................................... 5 III. Metaphysical motivations............................................................................................. 9 IV. From motivations to desiderata.................................................................................. 12 V. A map of the thesis...................................................................................................... 13 1. The rise and fall of linguistic modal conventionalism.................................................. 15 1.1 Logical positivism and early linguistic theories of modality.............................. 15 1.2 A. J. Ayer............................................................................................................ 20 1.3 Rudolf Carnap..................................................................................................... 22 1.4 W. V. Quine......................................................................................................... 26 1.5 Saul Kripke.......................................................................................................... 29 1.6 Hilary Putnam...................................................................................................... 33 1.7 Conclusion: desiderata revisited.......................................................................... 36 2. Modern linguistic modal conventionalism and the necessary a posteriori.................. 39 2.1 Sidelle’s modal conventionalism........................................................................ 39 2.2 Thomasson’s modal normativism....................................................................... 47 2.2.1 Linguistic rules and why we should believe in them............................... 47 2.2.2 Using linguistic rules to construct a theory of modality.......................... 51 2.3 Defending analyticity.......................................................................................... 55 2.4 Establishing parameters for LMC........................................................................ 58 2.4.1 Theodore Sider......................................................................................... 59 2.4.2 Ross Cameron.......................................................................................... 59 2.4.3 Iris Einheuser........................................................................................... 60 2.4.4 Dana Goswick.......................................................................................... 61 2.4.5 Simon Blackburn...................................................................................... 61 2.4.6 Conditions for LMC................................................................................. 62 2.4.7 Two notes: sentences and conventions.................................................... 63 2.5 Taking stock........................................................................................................ 65 3. Lost in a conventional world........................................................................................ 66 3.1 Modal properties and de re modal truth.............................................................. 66 3.2 Modal properties and conditions of existence, identity and persistence............. 69 3.3 Conventional modal properties and Leibniz’s Law............................................. 72 3.4 Is object conventionalism so bad?....................................................................... 76 3.5 Abelardian predicates.......................................................................................... 81 3.6 Heading deeper into the conventional maze........................................................ 84 4. Thomasson, Schiffer and a dilemma for linguistic modal conventionalism................. 85 4.1 Thomasson: the threat of object conventionalism............................................... 85 4.2 Thomasson on avoiding object conventionalism................................................. 88 4.3 A dilemma: conventional objects or real modality............................................. 93 4.3.1 The status of modal propositions............................................................. 93 4.3.2 The status of modal properties................................................................. 96 4.4 Easy ontology and pleonastic properties............................................................. 98 4.5 The cost of conventionalism.............................................................................. 104 5. In a conventional world, we decide what’s true......................................................... 105 5.1 Analyticity