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. (shrink)

Knowledge and its Limits presents a systematic new conception of knowledge as a kind of mental stage sensitive to the knower's environment. It makes a major contribution to the debate between externalist and internalist philosophies of mind, and breaks radically with the epistemological tradition of analyzing knowledge in terms of true belief. The theory casts new light on such philosophical problems as scepticism, evidence, probability and assertion, realism and anti-realism, and the limits of what can be known. The arguments are (...) illustrated by rigorous models based on epistemic logic and probability theory. The result is a new way of doing epistemology and a notable contribution to the philosophy of mind. (shrink)

Sorensen here offers a unified solution to a large family of philosophical puzzles and paradoxes through a study of "blindspots": consistent propositions that cannot be rationally accepted by certain individuals even though they might by true.

One tradition of solving the surprise exam paradox, started by Robert Binkley and continued by Doris Olin, Roy Sorensen and Jelle Gerbrandy, construes surpriseepistemically and relies upon the oddity of propositions akin to G. E. Moore’s paradoxical ‘p and I don’t believe that p.’ Here I argue for an analysis that evolves from Olin’s. My analysis is different from hers or indeed any of those in the tradition because it explicitly recognizes that there are two distinct reductios at work in (...) the student’s paradoxical argument against the teacher. The weak reductio is easy to fault. Its invalidity determines the structure of the strong reductio, so-calledbecause it is more difficult to refute, but ultimately unsound because of reasons associated with Moore-paradoxicality. Previous commentators have not always appreciated this difference, with the result that the strong reductio is not addressed, or the response to the weak reductio is superfl uous. This is one reason why other analyses in the tradition are vulnerable to objections to which mine is not. (shrink)

One tradition of solving the surprise exam paradox, started by Robert Binkley and continued by Doris Olin, Roy Sorensen and Jelle Gerbrandy, construes surpriseepistemically and relies upon the oddity of propositions akin to G. E. Moore’s paradoxical ‘p and I don’t believe that p.’ Here I argue for an analysis that evolves from Olin’s. My analysis is different from hers or indeed any of those in the tradition because it explicitly recognizes that there are two distinct reductios at work in (...) the student’s paradoxical argument against the teacher. The weak reductio is easy to fault. Its invalidity determines the structure of the strong reductio, so-calledbecause it is more difficult to refute, but ultimately unsound because of reasons associated with Moore-paradoxicality. Previous commentators have not always appreciated this difference, with the result that the strong reductio is not addressed, or the response to the weak reductio is superfl uous. This is one reason why other analyses in the tradition are vulnerable to objections to which mine is not. (shrink)

One tradition of solving the surprise exam paradox, started by Robert Binkley and continued by Doris Olin, Roy Sorensen and Jelle Gerbrandy, construes surpriseepistemically and relies upon the oddity of propositions akin to G. E. Moore’s paradoxical ‘p and I don’t believe that p.’ Here I argue for an analysis that evolves from Olin’s. My analysis is different from hers or indeed any of those in the tradition because it explicitly recognizes that there are two distinct reductios at work in (...) the student’s paradoxical argument against the teacher. The weak reductio is easy to fault. Its invalidity determines the structure of the strong reductio, so-calledbecause it is more difficult to refute, but ultimately unsound because of reasons associated with Moore-paradoxicality. Previous commentators have not always appreciated this difference, with the result that the strong reductio is not addressed, or the response to the weak reductio is superfl uous. This is one reason why other analyses in the tradition are vulnerable to objections to which mine is not. (shrink)

A new solution to the liar paradox is developed using the insight that it is illegitimate to even suppose (let alone assert) that a liar sentence has a truth-status (true or not) on the grounds that supposing this sentence to be true/not-true essentially defeats the telos of supposition in a readily identifiable way. On that basis, the paradox is blocked by restricting the Rule of Assumptions in Gentzen-style presentations of the sequent-calculus. The lesson of the liar is that not all (...) assumptions are for free. One merit of this proposal is that it is free from the revenge problem. (shrink)

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. (shrink)

An argument whose conclusion C is essential evidence for one of its premises can provide its target audience with justification for believing C. This is possible because we can enhance our justification for believing a proposition C by integrating it into an explanatory network of beliefs for which C itself provides essential evidence. I argue for this in light of relevant features of doxastic circularity, epistemic circularity, and explanatory inferences. Finally, I confirm my argument with an example and respond to (...) objections. (shrink)

Most of our knowledge is inexact, and known by us to be so. An example of such known inexactness will be described in some detail. The description seems to entail a contradiction. However, the paradoxical reasoning rests on an assumption. It will be suggested that the description is correct and this assumption false. Its failure will be explained by means of a picture of inexact knowledge in which the notion of a margin for error is central. This picture suggests diagnoses (...) of other paradoxical arguments: Surprise Examinations, backwards inductions about Iterated Prisoner's Dilemma, and the Heap. (shrink)

This is a defense and extension of Stephen Yablo's claim that self-reference is completely inessential to the liar paradox. An infinite sequence of sentences of the form 'None of these subsequent sentences are true' generates the same instability in assigning truth values. I argue Yablo's technique of substituting infinity for self-reference applies to all so-called 'self-referential' paradoxes. A representative sample is provided which includes counterparts of the preface paradox, Pseudo-Scotus's validity paradox, the Knower, and other enigmas of the genre. I (...) rebut objections that Yablo's paradox is not a genuine liar by constructing a sequence of liars that blend into Yablo's paradox. I rebut objections that Yablo's liar has hidden self-reference with a distinction between attributive and referential self-reference and appeals to Gregory Chaitin's algorithmic information theory. The paper concludes with comments on the mystique of self-reference. (shrink)

A formal theory of truth, alternative to tarski's 'orthodox' theory, based on truth-value gaps, is presented. the theory is proposed as a fairly plausible model for natural language and as one which allows rigorous definitions to be given for various intuitive concepts, such as those of 'grounded' and 'paradoxical' sentences.

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. (shrink)

On the basis of arguments showing that none of the most influential analyses of Moore’s paradox yields a successful resolution of the problem, a new analysis of it is offered. It is argued that, in attempting to render verdicts of either inconsistency or self-contradiction or self-refutation, those analyses have all failed to satisfactorily explain why a Moore-paradoxical proposition is such that it cannot be rationally believed. According to the proposed solution put forward here, a Moore-paradoxical proposition is one for which (...) the believer can have no non-overridden evidence. The arguments for this claim make use of some of Peter Klein’s views on epistemic defeasibility. It is further suggested that this proposal may have important meta-epistemological implications. (shrink)

(1984). Conditional blindspots and the knowledge squeeze: A solution to the prediction paradox. Australasian Journal of Philosophy: Vol. 62, No. 2, pp. 126-135.