Roy Sorensen

This chapter focuses on the property that excited Kuhn's interest in thought experiments: conflict vagueness. This property often generates inconsistent beliefs but is not itself inconsistency. Although it is absent from most thought experiments, a substantial portion of the most provocative thought experiments do spring from this species of vagueness; for they motivate conceptual reform by touching a nerve of indeterminacy. Hence, study of conflict vagueness reveals the ways thought experiments restructure our conceptual scheme.

THE PURPOSE OF THIS ARTICLE IS TO SHOW HOW HUME’S SCEPTICISM ABOUT MIRACLES GENERATES "EPISTEMOLOGICAL" SCEPTICISM ABOUT TIME TRAVEL. SO THE PRIMARY QUESTION RAISED HERE IS "CAN ONE KNOW THAT TIME TRAVEL HAS OCCURED?" RATHER THAN "CAN TIME TRAVEL OCCUR?" I ARGUE THAT ATTEMPTS TO SHOW THE EXISTENCE OF TIME TRAVEL WOULD FACE THE SAME METHODOLOGICAL PROBLEMS AS THE ONES CONFRONTING ATTEMPTS TO DEMONSTRATE THE EXISTENCE OF PARANORMAL EVENTS. SINCE HUMEAN SCEPTICISM EXTENDS TO THE STUDY OF PARANORMAL EVENTS (PARAPSYCHOLOGY), HUMEANS ARE COMMITTED TO SCEPTICISM ABOUT THE STUDY OF TIME TRAVEL ("PARAHISTORY")

A blindspot is a consistent but inaccessible proposition. For instance, I cannot know 'The test is on Friday but I do not know it'. No contradiction follows from the supposition that you know my blindspot. But could you know my blindspot if we are epistemic peers? Epistemic peers have the same evidence and reasoning ability. So either both peers know a proposition or both are ignorant. Since I cannot know my blindspot, neither can my peer. Thus the formal ignorance associated with blindspots spreads to my peers. This contagion is used to improve a solution to the blindspot solution to the surprise test paradox.

The aim of this paper is to show how thought experiments help us learn about laws. After providing examples of this kind of nomic illumination in the first section, I canvass explanations of our modal knowledge and opt for an evolutionary account. The basic application is that the laws of nature have led us to develop rough and ready intuitions of physical possibility which are then exploited by thought experimenters to reveal some of the very laws responsible for those intuitions. The good news is that natural selection ensures a degree of reliability for the intuitions. The bad news is that the evolutionary account seems to limit the range of reliable thought experiment to highly practical and concrete contexts. In the fifth section, I provide reasons for thinking that we are not as slavishly limited as a pessimistic construal of natural selection suggests. Nevertheless, I promote the idea that biology is a promising source of predictions and diagnoses of thought experiment failures.

Epistemologists have profited from studies of the ways in which ‘know’ is ambiguous. We can also profit by studying the ways in which ‘know’ is vague. After classifying sources of vagueness for ‘know,’ I spend the second section examining theories of vagueness. With the exception of the theory that vague predicates are incoherent, which I try to refute, we need not take a stand on a particular theory to show that the vagueness of knowledge has substantive epistemological implications. The third section supports the thesis through a survey of ways in which appeals to vagueness can be applied to the field's issues. First, I show how higher order vagueness is evidence against the KK thesis, the incorrigibility of sense data, and the completability of epistemology. An interesting resemblance between infinity and vagueness provides the point of departure for the next type of application. For this resemblance suggests a new way of handling apparently infinite belief structures. The approach is illustrated with an analysis of common knowledge. The third type of application concerns the ways in which disguised sorites creep into our thinking about knowledge. In addition to brief illustrations concerning naive holism, question begging, and an objection to incorrigibilism, I provide more detailed illustrations involving Jonathan Adler's sceptical appeal to epistemic universalizability, the prediction paradox, and William Lycan's objection to Gilbert Harman's social knowledge cases. I conclude with some general remarks on the lessons to be learned from the vagueness of knowledge.

Can merely thinking about an imaginary situation provide evidence for how the world actually is--or how it ought to be? In this lively book, Roy A. Sorensen addresses this question with an analysis of a wide variety of thought experiments ranging from aesthetics to zoology. Presenting the first general theory of thought experiment, he sets it within an evolutionary framework and integrates recent advances in experimental psychology and the history of science, with special emphasis on Ernst Mach and Thomas Kuhn. Sorensen explores what thought experiments are, how they work, and what their virtues and vices are. In his view, philosophy differs from science in degree, but not in kind. For this reason, he claims, it is possible to understand philosophical thought experiments by concentrating on their resemblance to scientific relatives. Sorensen assesses the hazards of thought experiments and grants that there are interesting ways in which the method leads us astray, but attacks most scepticism about thought experiments as arbitrary. He maintains that they should be used--as they generally are--as part of a diversified portfolio of techniques, creating a network of cross-checks that make for impressive reliability.

Ludwig Wittgenstein once exclaimed that the most important philosophical discovery made by G.E. Moore was of the oddity of sentences like 'It is raining but I do not believe it'. This dissertation can be viewed as a partial vindication of Wittgenstein's enthusiasm. ;However, my direct target is the prediction paradox. In the first chapter, the history of the prediction paradox is covered in detail. With the help of some new variations of the prediction paradox, I then argue in Chapter II that the paradox has not yet been solved. Chapter III contains my solution to Moore's problem. My concept of an epistemic blindspot emerges from this chapter and is used to establish new kinds of limits on knowledge in Chapter IV. In the following chapter I argue that the prediction paradox is a symptom of our unfamiliarity with these limits. Thus the prediction paradox is part of a general epistemological problem rather than an isolated logical problem. I try to make this claim more plausible in Chapter VI by applying the lessons learned about these new limits for epistemology to the more traditional philosophical problems associated with predictive determinism. Along the way I show that disagreement amongst ideal thinkers is possible. I use this possibility to argue against emulation theories of moral problem solving, like ideal observer theories, conventionalism, and the Rawlsian appeal to the original position. I conclude the chapter by using epistemic blindspots as counterexamples to predictive determinism and retrodictive determinism. Having shown how pre-decisional blindspots have been illicitly employed to support the thesis that decisions are uncaused in Chapter VI, I argue in Chapter VII that post-decisional blindspots are involved in Newcomb's problem. A solution to this problem is then proposed. In my concluding remarks I provide a general characterization of my approach to the philosophical problems that have concerned me in this dissertation and a brief summation of its results