MODAL ARGUMENTS, POSSIBLE EVIDENCE AND CONTINGENT METAPHYSICS Michael Thomas Traynor A Thesis Submitted for the Degree of PhD at the University of St Andrews 2017 Full metadata for this item is available in St Andrews Research Repository at: http://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/15595 This item is protected by original copyright Modal Arguments, Possible Evidence and Contingent Metaphysics. Michael Thomas Traynor This thesis is submitted in partial fulfilment for the degree of PhD at the University of St Andrews Date of submission: 23/09/2016 1 Abstract. The present work explores various ways in which contingent evidence can impact metaphysics, while advocating that, just as a scientific realist allows for ampliative inferences to the unobservable, ampliative inferences from possible evidence can warrant possibility claims that lie beyond the reach of sensorial imagination. In slogan form: possible evidence is a guide to possibility. Drawing on Shoemaker’s (1969) argument for the possibility of time without change, I advocate the following principle: If there is a possible world at which the observable facts make it objectively reasonable to conclude that p, then we should conclude that p is possibly true. This provides a route to contingentism in metaphysics, for, if one considers that there are worlds in which the observable facts make it objectively reasonable to conclude that p, and worlds in which the observable facts make it objectively reasonable to conclude that not-p, then my principle tells us that we should conclude that possibly-p and possibly not-p, i.e. that p is contingent. This contingency in what is reasonable to conclude, I suggest, occurs most saliently in debates where evidence of phenomenal experience and empirical science are marshalled to support one theory over another. I also explore some consequences of taking possible evidence to be a guide to possibility in this way, among them being an interesting modal analogue of the lottery paradox. 2 Acknowledgements. Thanks to everyone at the Arche Philosophical Research Centre, and everyone who contributed to the Metaphysics Research Group, particularly those who came to my talks and provided comments and criticism. Some of the material of Chapter 1 arose out of early conversations with Martin Lipman and was subsequently presented at the Joint Session of the Aristotelian Society and Mind Association and published in the Proceedings (114, Issue 3 part 3, 2014). I am grateful to everyone who commented during the talk and those who afterwards provided challenging and constructive criticism. Much of Chapter 2 was presented at the 7th Annual CMM Graduate Conference at Leeds in 2013; I am grateful for the feedback, particularly from Ross Cameron, who responded to the paper. Some of the central ideas of Chapter 2 were also published in Thought (Vol. 2, Issue 3, 2013), and I am grateful to Nikk Effingham for providing a response. I have incorporated Cameron’s and Effingham’s responses into the chapter. Thanks to my parents, Tom and Androulla Traynor. Thanks to the AHRC and the Royal Institute of Philosophy (Jacobsen Trust) for funding my research. Lastly, thanks to my supervisors, Katherine Hawley and Aaron Cotnoir, for innumerable conversations and guidance throughout. 4 Contents. 0. Introduction. (p.7) 1. Cameron’s negative route to contingentism. 2. Positive routes to contingentism. 3. Science as a guide to metaphysics. 4. Impossible experiments and unobservables. 5. Chapter summaries. 1. Contingent Scientific and Phenomenal Evidence. (p.31) 1.Experience as evidence for the passage of time. 2. Could we experience the passage of time? 3. Experience of ordinary objects. 4. Prosser’s argument adapted to perception of ordinary objects. 5. Non-metaphysical explanations, and their contingency 6. Assuming necessity to refuse experiential evidence. 7. The conceptual and empirical case against A theory. 8. Concluding remarks. 2. Actual Time and Possible Change: On Modal Motivations for Mereological Harmony. (p.68) 1. Grounding Possibilities in Parts: Sider’s Desk, Hawley’s Homogeneous Object. 2. Actual Time and Possible Change: The Problem Stated. 3. Potential Objections. 4. The contingent explanatory power of temporal parts. 5. Cameron’s modified version of the Sider-Hawley modal argument. 6. Effingham: An Alternative Harmony. 7. Structure as a guide to possibility? 8. Extending the argument to make a case against temporal parts. 9. A similar issue for reductionism about time. 10. Concluding remarks. 3. The Vanishing of Almost-Indiscernibility in the Case Against PII. (p.106) 1. Introduction. 2. Almost Black’s spheres. 3. Attempting to bridge the ‘surely-gap’ with causal independence. 4. Adams’s as a Subtraction Argument? 5. An Argument from Continuity? 6. Explaining away the intuition: Nature doesn’t make jumps, but modal space might. 7. Distinct indiscernibles as figuring in the best explanation of contingent phenomena: the case from quantum physics. 4. Part I: Imaginative resistance, possible evidence and genuinely new ideas. (p.131) 1. Genuinely new ideas. 2. The dependency thesis and the limits of experience. 3. Imaginative resistance. 4. Shoemaker’s argument from the possibility of partial freezes. 5. Beyond potential experience, via possible inductions. 6. Warmbrod’s Criticism. 7. Beyond imagination, via imagined evidence 5 4. Part II: Possible evidence as a guide to possibility. (p.158) 8. An implied modal epistemology. 9. Comparing Hanrahan’s Modal Explanationism. 10. The Possible Evidence Principle, and Potential Objections. 11. Further examples of the principle at work. 12. Concluding remarks. 5. Abduction, Agglomeration, A Priority, and Necessity. (p.191) 1. Introduction. 2. Modal echoes of the lottery paradox. 3. A priority, necessity, and agglomeration. 4. Should we reject agglomeration of a priori justified beliefs? 5. Contingentism, abduction, and agglomeration. 6. Abduction and Modality: Choosing a necessity claim from a range of potential explanations. 6. Final Thoughts. (p.223) 6 0. Introduction. “Empirical science at most tells us what is the case, not what must or may be (but happens not to be) the case. Metaphysics deals in possibilities.” (Lowe, The Possibility of Metaphysics: Substance, Identity, and Time (1998, p. 5)) “If we had to travel to other possible worlds to learn what goes on there, we could know nothing about uninstantiated possibilities or necessities; for possible worlds are not foreign countries or planets. Rather, they are alternative complete universes and so are physically inaccessible. Nevertheless, there are standard patterns of inference entitling us to infer facts about ways things could be – about other possible worlds.” (Sorensen, Thought Experiments (1992, p. 77)) It is common in philosophy to appeal to imagination for evidence concerning what is possible. Hart (1988) and Yablo (1993) have suggested a compelling analogy to make sense of this: Imagination is to the possible as perception is to the actual. There are limits to the justificatory force of imagination, however, particularly where there is disagreement about what we are able to imagine. I argue that appealing to possible evidence can justify certain possibility claims even if the possibility in question is beyond confirmation by either experience or imagination. In slogan form: possible evidence is a guide to possibility. I will defend the principle that if there is a possible world in which the observable facts make it objectively reasonable to conclude that p, then it is objectively reasonable for us to conclude 7 that p is possibly true. Let’s call this the Possible Evidence Principle: PEP. PEP is valuable in cases where direct experience could not, in principle, confirm a claim whose possibility is being debated; for instance, the claim that time passes without change (since any observation of the passage of time plausibly requires changes in the observed), that there are distinct indiscernible objects, that the universe has doubled in size, that space is absolute, or that machines think. Just as scientific realism allows that ampliative inferences can lead us to conclusions beyond what can be directly confirmed by observation, so possible ampliative inferences can lead us to possibility claims beyond what can be confirmed by sensory imagination. The present work thus explores various ways in which contingent, underdetermining evidence can impact metaphysics. One of the central claims is that, where the case for a certain metaphysical thesis depends significantly on contingent matters, this should lead us to conclude that the metaphysical thesis is also a matter of contingency. The observable facts in different possible worlds may make it objectively reasonable to infer different theses; where the different theses in question are rival metaphysical claims, the PEP tells us that the debate in question is a contingent matter. Thus my principle suggests a positive route to contingentism in certain matters of metaphysics, building on Cameron’s (2007) argument against the necessitarian presumption. This introductory chapter introduces some of the main themes underlying the thesis – contingency and necessity in metaphysics, scientific realism, the bearing of science (and experience more generally) on metaphysical questions, unobservables in science and metaphysics, modal knowledge and the limits of imagination – and attempts to give a sense of the ways in which I intend