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- N. Hall (1999). How to Set a Surprise Exam. Mind 108 (432):647-703.The professor announces a surprise exam for the upcoming week; her clever student purports to demonstrate by reductio that she cannot possibly give such an exam. Diagnosing his puzzling argument reveals a deeper puzzle: Is the student justified in believing the announcement? It would seem so, particularly if the upcoming 'week' is long enough. On the other hand, a plausible principle states that if, at the outset, the student is justified in believing some proposition, then he is also justified in believing that he will continue to be justified in believing that proposition. It follows from this 'confidence' principle that the student is not justified in believing the announcement, regardless of the number of days in the week. I argue that the key to resolving this dilemma is to distinguish the confidence principle from a slightly weaker principle governing the student's justified degrees of belief. Representing these degrees of belief as probabilities, and taking 'justified belief' to mean 'justified degree of belief above a certain threshold', I show that we can uphold the weaker, probabilistic analog to the confidence principle, and maintain that, provided the 'week' is long enough, the student can justifiably believe the announcement. The resulting probabilistic analysis of the story leads to a new diagnosis of the logical flaw in the student's reasoning, and suggests, finally, that even those early stages of it which are logically impeccable exhibit another kind of flaw: circularity.
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This paper proposes a game-theoretic solution of the surprise examination problem. It is argued that the game of “matching pennies” provides a useful model for the interaction of a teacher who wants her exam to be surprising and students who want to avoid being surprised. A distinction is drawn between prudential and evidential versions of the problem. In both, the teacher should not assign a probability of zero to giving the exam on the last day. This representation of the problem provides a diagnosis of where the backwards induction argument, which “proves” that no surprise exam is possible, is mistaken.
Deductive and inductive logic confront this skeptical challenge: we can justify any logical principle only by means of an argument but we can acquire justification by means of an argument only if we are already justified in believing some logical principle. We could solve this problem if probative arguments do not require justified belief in their corresponding conditionals. For if not, then inferential justification would not require justified belief in any logical principle. So even arguments whose corresponding conditionals are epistemically dependent upon their conclusions--epistemically self-supporting arguments--need not be viciously circular. R. B. Braithwaite and James Van Cleve use internalist and externalist versions of this strategy in their proposed solutions to the problem of induction. Unfortunately, their arguments for self-support are unsound and any theory of inferential justification that does not require justified belief in the corresponding conditionals of justification-affording arguments is unacceptably arbitrary. So self-supporting arguments cannot be justification-creating.
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Evidentialism is the view that facts about whether or not an agent is justified in having a particular belief are entirely determined by facts about the agent’s evidence; the agent’s practical needs and interests are irrelevant. I examine an array of arguments against evidentialism (by Jeremy Fantl, Matthew McGrath, David Owens, and others), and demonstrate how their force is affected when we take into account the relation between degrees of belief and outright belief. Once we are sensitive to one of the factors that secure thresholds for outright believing (namely, outright believing that p in a given circumstance requires, at the minimum, that one’s degree of belief that p is high enough for one to be willing to act as if p in the circumstances), we see how pragmatic considerations can be relevant to facts about whether or not an agent is justified in believing that p—but largely as a consequence of the pragmatic constraints on outright believing.
We commonly speak of people as being ‘‘justified’’ or ‘‘unjustified’’ in believing as they do. These terms describe a person’s epistemic condition. To be justified in believing as one does is to have a positive epistemic status in virtue of holding one’s belief in a way which fully satisfies the relevant epistemic requirements or norms. This requires something more (or other) than simply believing a proposition whose truth is well-supported by evidence, even by evidence which one possesses oneself, since one could entirely miss the relevance of this evidence and hold the belief as a result of wishful thinking or for some other bad reason. My topic in this paper is the notion of being justified which precludes beliefs flawed in this way. I will take the notion of something’s telling in favor of the truth of a proposition—that is, the notion of evidential support—for granted.
Theories of epistemically justified belief have long assumed individualism. In its extreme, or Lockean, form individualism rules out justified belief on testimony by insisting that a subject is justified in believing a proposition only if he or she possesses first-hand justification for it. The skeptical consequences of extreme individualism have led many to adopt a milder version, attributable to Hume, on which a subject is justified in believing a proposition only if he or she is justified in believing that there is testimony in favor of the proposition deriving from a reliable source. I argue that this Humean individualism also leads to skepticism in a wide range of cases; it makes it impossible for a layperson to be justified on expert testimony. In addition, I argue that the apparent motivation for the Humean view, an insistence on intellectual autonomy in justification, does not succeed in motivating it. I then explore the contours of a collectivist view of justification on testimony, with special attention to the place of a subject's intellectual autonomy in such justification. I try to bring empirical results of the psychology of persuasion to bear on the epistemological issues.
Richard Fumerton’s “Principle of Inferential Justification” holds that, in order to be justified in believing P on the basis of E, one must be justified in believing that E makes P probable. I argue that the plausibility of this principle rests upon two kinds of mistakes: first, a level confusion; and second, a fallacy of misconditionalisation. Furthermore, Fumerton’s principle leads to skepticism about inferential justification, for which reason it should be rejected. Instead, the examples Fumerton uses to motivate his principle can be accounted for using a different principle: in order for S to be justified in believing P on the basis of E, it must be true that E makes P probable. The latter principle can be independently motivated and does not lead to skepticism.
The Surprise Exam Paradox continues to perplex and torment despite the many solutions that have been offered. This paper proposes to end the intrigue once and for all by refuting one of the central pillars of the Surprise Exam Paradox, the 'No Friday Argument,' which concludes that an exam given on the last day of the testing period cannot be a surprise. This refutation consists of three arguments, all of which are borrowed from the literature: the 'Unprojectible Announcement Argument,' the 'Wright & Sudbury Argument,' and the 'Epistemic Blindspot Argument.' The reason that the Surprise Exam Paradox has persisted this long is not because any of these arguments is problematic. On the contrary, each of them is correct. The reason that it has persisted so long is because each argument is only part of the solution. The correct solution requires all three of them to be combined together. Once they are, we may see exactly why the No Friday Argument fails and therefore why we have a solution to the Surprise Exam Paradox that should stick.
The following principles may plausibly be included in a wide range of theories of epistemic justification: (1) There are circumstances in which an agent is justified in believing a falsehood, (2) There are circumstances in which an agent is justified in believing a principle of epistemic justification, (3) Beliefs acquired in compliance with a justifiably-believed epistemic principle are justified. I argue that it follows from these three individually plausible claims that an agent's belief may be both justified and unjustified. I consider how theories may avoid this paradox, and conclude that deontological theories of epistemic justification face considerable, perhaps insurmountable, difficulties.
Epistemologists often offer theories of justification without paying much attention to the variety and diversity of locutions in which the notion of justification appears. For example, consider the following claims which contain some notion of justification: B is a justified belief, S's belief that p is justified, p is justified for S, S is justified in believing that p, S justifiably believes that p, S's believing p is justified, there is justification for S to believe that p, there is justification for S's believing p, and S has a justification for believing that p. In addition to these passive uses of the notion of justification, there are active uses as well: S justified his belief in p, believing e justifies believing p, etc. The syntactic variety involves semantic difference as well. For example, the proposition S has a justification for believing that p does not entail that S believes p, whereas the proposition S justifiably believes that p does entail that S believes p.
Our ultimate goal is to show that this diversity is only superficial by arguing that there is a basic kind of justification. On the way, however, we shall argue that there are three central uses of a notion of justifica- tion in the above list: propositional justification (as in p is justified for S), personal justification (as in S is justified in believing that p) and doxastic justification (as in S's believing p is justified). Our preliminary argument will be that the multiplicity above can be explained in terms of these three locutions, and the substance of our argument will be to show that one of these three is the basic kind of justification. Success in this task will thereby justify, at least in part, the practice of contem- porary epistemologists. Our conclusions, however, shall not be of much comfort to contemporary epistemology, for the way in which the apparent diversity in the uses of the notion of justification is eliminated undermines much of recent epistemology.
I am justified in believing that my lottery ticket—call it t1—will not win, on statistical grounds. Those grounds apply equally to any other ticket, so I am justified in believing of any other ticket ti (let i take values from 2 to 1000000) that it will not win. I am not, however, justified in believing the giant conjunctive proposition that t1 will not win & t2 will not win & . . . & t1,000,000 will not win. On the contrary, I am justified in believing that some ticket will win, hence that one of those conjuncts is false. Suggested solution: justified belief is not closed under conjunction. It does not follow from the fact that I am justified in believing p and justified in believing q that I am justified in believing p & q.
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Discussion of N. Hall, How to set a surprise exam
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