A key question in the philosophy of logic is how we have epistemic justification for claims about logical entailment (assuming we have such justification at all). Justification holism asserts that claims of logical entailment can only be justified in the context of an entire logical theory, e.g., classical, intuitionistic, paraconsistent, paracomplete etc. According to holism, claims of logical entailment cannot be atomistically justified as isolated statements, independently of theory choice. At present there is a developing interest in—and endorsement of—justification holism (...) due to the revival of an abductivist approach to the epistemology of logic. This paper presents an argument against holism by establishing a foundational entailment-sentence of deduction which is justified independently of theory choice and outside the context of a whole logical theory. (shrink)

This paper discusses the Uniqueness Thesis, a core thesis in the epistemology of disagreement. After presenting uniqueness and clarifying relevant terms, a novel counterexample to the thesis will be introduced. This counterexample involves logical disagreement. Several objections to the counterexample are then considered, and it is argued that the best responses to the counterexample all undermine the initial motivation for uniqueness.

While the epistemic significance of disagreement has been a popular topic in epistemology for at least a decade, little attention has been paid to logical disagreement. This monograph is meant as a remedy. The text starts with an extensive literature review of the epistemology of (peer) disagreement and sets the stage for an epistemological study of logical disagreement. The guiding thread for the rest of the work is then three distinct readings of the ambiguous term ‘logical disagreement’. Chapters 1 and (...) 2 focus on the Ad Hoc Reading according to which logical disagreements occur when two subjects take incompatible doxastic attitudes toward a specific proposition in or about logic. Chapter 2 presents a new counterexample to the widely discussed Uniqueness Thesis. Chapters 3 and 4 focus on the Theory Choice Reading of ‘logical disagreement’. According to this interpretation, logical disagreements occur at the level of entire logical theories rather than individual entailment-claims. Chapter 4 concerns a key question from the philosophy of logic, viz., how we have epistemic justification for claims about logical consequence. In Chapters 5 and 6 we turn to the Akrasia Reading. On this reading, logical disagreements occur when there is a mismatch between the deductive strength of one’s background logic and the logical theory one prefers (officially). Chapter 6 introduces logical akrasia by analogy to epistemic akrasia and presents a novel dilemma. Chapter 7 revisits the epistemology of peer disagreement and argues that the epistemic significance of central principles from the literature are at best deflated in the context of logical disagreement. The chapter also develops a simple formal model of deep disagreement in Default Logic, relating this to our general discussion of logical disagreement. The monograph ends in an epilogue with some reflections on the potential epistemic significance of convergence in logical theorizing. (shrink)

Default logic has been a very active research topic in artificial intelligence since the early 1980s, but has not received as much attention in the philosophical literature thus far. This paper shows one way in which the technical tools of artificial intelligence can be applied in contemporary epistemology by modeling a paradigmatic case of deep disagreement using default logic. In §1 model-building viewed as a kind of philosophical progress is briefly motivated, while §2 introduces the case of deep disagreement we (...) aim to model. On the heels of this, §3 defines our formal framework, viz., a refined Horty-style default logic. §4 then uses the framework to model deep disagreement, and finally §5 provides a critical discussion of the result. (shrink)

The aim of this paper is threefold. Firstly, §1 and §2 introduce the novel concept logical akrasia by analogy to epistemic akrasia. If successful, the initial sections will draw attention to an interesting akratic phenomenon which has not received much attention in the literature on akrasia (although it has been discussed by logicians in different terms). Secondly, §3 and §4 present a dilemma related to logical akrasia. From a case involving the consistency of Peano Arithmetic and Gödel’s Second Incompleteness Theorem (...) it’s shown that either we must be agnostic about the consistency of Peano Arithmetic or akratic in our arithmetical theorizing. If successful, these sections will underscore the pertinence and persistence of akrasia in arithmetic (by appeal to Gödel’s seminal work). Thirdly, §5 concludes by suggesting a way of translating the dilemma of arithmetical akrasia into a case of regular epistemic akrasia; and further how one might try to escape the dilemma when it’s framed this way. (shrink)

This paper argues for the reasonableness of an inclusive conception of default reasoning. The inclusive conception allows untriggered default rules to influence beliefs: Since a default “from φ, infer ψ” is a defeasible inference rule, it by default warrants a belief in the material implication φ → ψ, even if φ is not believed. Such inferences are not allowed in standard default logic of the Reiter tradition, but are reasonable by analogy to the Deduction Theorem for classical logic. Our main (...) contribution is a formal framework for inclusive default reasoning. The framework has a solid philosophical foundation, it draws conclusions non-trivially different from non-inclusive frameworks, and it exhibits a host of benchmark properties deemed desirable in the literature—e.g., that extensions always exist and are consistent. (shrink)

This paper discusses the uniqueness thesis, a core thesis in the epistemology of disagreement. After presenting uniqueness and clarifying relevant terms, a novel counterexample to the thesis will be introduced. This counterexample involves logical disagreement. Several objections to the counterexample are then considered, and it is argued that the best responses to the counterexample all undermine the initial motivation for uniqueness.

This paper sketches a general account of how to respond in an epistemically rational way to moral disagreement. Roughly, the account states that when two parties, A and B, disagree as to whether p, A says p while B says not-p, this is higher-order evidence that A has made a cognitive error on the first-order level of reasoning in coming to believe that p (and likewise for B with respect to not-p). If such higher-order evidence is not defeated, then one (...) rationally ought to reduce one’s confidence with respect to the proposition in question. We term this the higher-order evidence account (the HOE account), and present it as a superior to what we might call standard conciliationism, which holds that when agents A and B disagree about p, and are (known) epistemic peers, they should both suspend judgement about p or adjust their confidence towards the mean of A and B’s prior credences in p. Many have suspected that standard conciliationism is implausible and may have skeptical implications. After presenting the HOE account, we put it to work by applying it to a range of cases of moral disagreement, including those that have feature in recent debates assuming standard conciliationism. We show that the HOE account support reasonable, non-skeptical verdicts in a range of cases. Note that this is a paper on moral disagreement, not on the HOE account, thus the account is merely stated here, while defended more fully elsewhere. (shrink)

Recently an abductivist approach to the epistemology of logic has gained traction. A necessary component of logical abductivism is justification holism, asserting that claims of logical entailment can only be justified in the context of an entire logical theory, e.g., classical, intuitionistic, etc. One view that is incompatible with abductivism is an atomistic view on which individual entailment-claims can be justified point-wise rather than in the context of a whole theory. This paper provides two atomistic counterexamples to justification holism in (...) the epistemology of logic. Both examples appeal to pre-theoretic commitments of deductive validity. The main aim is to show that there are some foundational entailment-claims for which we can have propositional justification independently of theory choice and outside the context of a whole logical theory. If one were to give up on these foundational claims, all semantic and syntactic accounts of deductive validity would be non-starters. (shrink)

In this chapter we explore the topic of logical disagreement. Though disagreement in general has attracted widespread philosophical interest, both in epistemology and philosophy of language, the general issues surrounding disagreement have only rarely been applied to logical disagreement in particular. Here, we develop some of the fascinating semantic and epistemological puzzles to which logical disagreement gives rise. In particular, after distinguishing between different types of logical disagreement, we explore some connections between logical disagreements and deep disagreements over fundamental epistemic (...) principles; we discuss several semantic puzzles that arise on various accounts of the meanings of logical terms; we investigate how such disagreements relate to Kripke’s so-called “Adoption Problem”; and we probe epistemological puzzles that arise from disagreements about logic in the light of central principles from the peer disagreement literature. (shrink)

The overall aim of this article is to reorient the contemporary debate about epistemic consequentialism. Thus far the debate has to a large extent focused on whether standard theories of epistemic justification are consequentialist in nature and therefore vulnerable to certain trade-off cases where accepting a false or unjustified belief leads to good epistemic outcomes. We claim that these trade-offs raise an important—yet somewhat neglected—issue about the epistemic demands on inquiry. We first distinguish between two different kinds of epistemic evaluation, (...) viz., backing evaluation and outcome evaluation, and then go on to outline and discuss a consequentialist metatheory about the right combinations of decision procedures to adopt in inquiry. Note that the piece is exploratory in the following sense: we try to explore epistemic evaluation in consequentialist terms, which involves stating a form of epistemic consequentialism, but also pointing to what non-consequentialist alternatives might be. Rather than trying to argue decisively for a particular conclusion, we aim to outline various intricate issues in an underexplored area of theorizing. In the course of doing this, we’ll transpose some well-known themes from discussions of consequentialism in ethics to the current debate about consequentialism in epistemology, e.g., agent-neutrality, options, and side-constraints. (shrink)

This paper aims to show that Selim Berker’s widely discussed prime number case is merely an instance of the well-known generality problem for process reliabilism and thus arguably not as interesting a case as one might have thought. Initially, Berker’s case is introduced and interpreted. Then the most recent response to the case from the literature is presented. Eventually, it is argued that Berker’s case is nothing but a straightforward consequence of the generality problem, i.e., the problematic aspect of the (...) case for process reliabilism (if any) is already captured by the generality problem. (shrink)

Den filosofiske position konsekventialisme er ofte genstand for debat i filosofikredse, men alt for hyppigt opstår der misforståelser blandt de involverede, fordi de ikke er eksplicitte, hvad grundantagelser og væsentlige distinktioner angår. Denne korte artikel vil give en approksimation af, hvad der forstås ved konsekventialisme på et generisk niveau. Målet med artiklen er at klargøre nogle af de grundantagelser og distinktioner, som konsekventialister ofte benytter i deres teoridannelse, og som bør holdes for øje i ønsket om en frugtbar debat.