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)

Is it morally permissible to spy on allied countries? What type of otherwise criminal acts may covert intelligence agents commit in order to keep their cover? Is it permissible to subject children of high-value targets to covert surveillance? In this article, I ask whether democratically elected politicians ought to rely on advice from ethics committees in answering moral choices in secret policy. I argue that ethics committees should not advise politicians on how they ought to conclude secret moral choices. Instead, (...) we can mandate ethics committees to provide advice aimed at improving the moral reasoning behind moral decisions in secret policy. Such advice, I argue, may add value to the decision process independently of whether it increases the chances of reaching morally correct conclusions. (shrink)

The argument from moral disagreement contends that if moral realism is true, there would not be the kind of moral disagreement that there is and hence, that moral realism is false. Convergentist moral realists grant that a particular kind of moral disagreement would pose a problem for moral realism but argue that the moral disagreements of which we have empirical evidence are not that kind. To do so they offer alternative, defusing explanations of them. I critique two such defusing explanations. (...) The first argues that these disagreements are not the right kind because their disputants agree about moral values (C. D. Meyers 2013). I argue that it fails because it commits moral realism to a convergence on moral values which does not obtain. The second argues that these disagreements are not the right kind because their moral disputants’ views were not formed with a method that moral realists think provides epistemic access to moral facts (i.e., reflective equilibrium) (Fitzpatrick 2014). I argue that it fails because it requires reflective equilibrium to generate a convergence that it probably does not and if reflective equilibrium generates convergence in idealized conditions, this defusing explanation does not preserve the epistemic access that convergentists seek to preserve. Hence, I argue, convergentists have reason to be cautious about endorsing reflective equilibrium as the sole method of moral inquiry. I then consider a version of the argument from moral disagreement that argues that the best explanation of contemporary philosophers’ disagreement about our objective reasons for action is that there are no such reasons (Leiter 2021). I argue that that they have different evidence is a better explanation. (shrink)