Robert Aumann presents his Agreement Theorem as the key conditional: “if two people have the same priors and their posteriors for an event A are common knowledge, then these posteriors are equal” (Aumann, 1976, p. 1236). This paper focuses on four assumptions which are used in Aumann’s proof but are not explicit in the key conditional: (1) that agents commonly know, of some prior μ, that it is the common prior; (2) that agents commonly know that each of them updates (...) on the prior by conditionalization; (3) that agents commonly know that if an agent knows a proposition, she knows that she knows that proposition (the “K K” principle); (4) that agents commonly know that they each update only on true propositions. It is shown that natural weakenings of any one of these strong assumptions can lead to countermodels to Aumann’s key conditional. Examples are given in which agents who have a common prior and commonly know what probability they each assign to a proposition nevertheless assign that proposition unequal probabilities. To alter Aumann’s famous slogan: people can “agree to disagree”, even if they share a common prior. The epistemological significance of these examples is presented in terms of their role in a defense of the Uniqueness Thesis: If an agent whose total evidence is E is fully rational in taking doxastic attitude D to P, then necessarily, any subject with total evidence E who takes a different attitude to P is less than fully rational. (shrink)

Believing rationally is epistemically valuable, or so we tend to think. It’s something we strive for in our own beliefs, and we criticize others for falling short of it. We theorize about rationality, in part, because we want to be rational. But why? I argue that how we answer this question depends on how permissive our theory of rationality is. Impermissive and extremely permissive views can give good answers; moderately permissive views cannot.

In this paper, I begin by defending permissivism: the claim that, sometimes, there is more than one way to rationally respond to a given body of evidence. Then I argue that, if we accept permissivism, certain worries that arise as a result of learning that our beliefs were caused by the communities we grew up in, the schools we went to, or other irrelevant influences dissipate. The basic strategy is as follows: First, I try to pinpoint what makes irrelevant influences (...) worrying and I come up with two candidate principles. I then argue that one principle should be rejected because it is inconsistent with permissivism. The principle we should accept implies that it is sometimes rational to maintain our beliefs, even upon learning that they were caused by irrelevant influences. (shrink)

In this article, I consider how the epistemic problem of religious disagreement has been viewed within the Islamic tradition. Specifically, I consider two religious epistemological trends within the tradition: Islamic Rationalism and Islamic Traditionalism. In examining the approaches of both trends toward addressing the epistemic problem, I suggest that neither is wholly adequate. Nonetheless, I argue that both approaches offer insights that might be relevant to building a more adequate response. So, I attempt to combine insights from both by drawing (...) a distinction between inferential and noninferential reflective responsibility. Given this distinction, I argue that it may be possible for a theist to remain steadfast in upholding their tradition-specific theistic belief, without having to hold that belief by way of inference; but nevertheless, having to be sufficiently reflectively responsible in forming their theistic belief noninferentially. (shrink)

Standard models in epistemic game theory make strong assumptions about agents’ knowledge of their own beliefs. Agents are typically assumed to be introspectively omniscient: if an agent believes an event with probability p, she is certain that she believes it with probability p. This paper investigates the extent to which this assumption can be relaxed while preserving some standard epistemic results. Geanakoplos (1989) claims to provide an Agreement Theorem using the “truth” axiom, together with the property of balancedness, a significant (...) relaxation of introspective omniscience. I provide an example which shows that Geanakoplos’s statement is incorrect. I then introduce a new property, local balancedness, which allows us both to correct Geanakoplos’s result, and to extend it to cases where the truth axiom may fail. I exploit this general Agreement Theorem to provide novel epistemic conditions for correlated and Nash equilibrium, both of which relax the assumption of introspective omniscience. In all three cases, the results are also extended to infinite state spaces. (This is Chapter 5 of my 2014 Oxford DPhil (PhD) thesis.). (shrink)

A good account of the agnostic attitude of Suspending Judgement should explain how it can be rendered more or less rational/justified according to the state of one's evidence – and one's relation to that evidence. I argue that the attitude of suspending judgement whether p constitutively involves having a belief; roughly, a belief that one cannot yet tell whether or not p. I show that a theory of suspending that treats it as a sui generis attitude, wholly distinct from belief, (...) struggles to account for how suspension of judgement can be rendered more or less rational (or irrational) by one's evidence. I also criticise the related idea that suspension essentially requires an 'Inquiring Attitude'. I show how a belief-based theory, in contrast, neatly accounts for the rational and epistemic features of suspending and so neatly accounts for why an agnostic has a genuine neutral opinion concerning the question whether p, as opposed to simply having no opinion. (shrink)

In recent debates over permissivism and uniqueness—two theses concerning the relationship between evidence and epistemic rationality—some philosophers have claimed that permissivism has an intuitive advantage over uniqueness. I examine the cases alleged to intuitively motivate permissivism and suggest they do not provide prima facie support for permissivism. I conclude by explaining how my discussion bears on whether permissivism can defeat skeptical arguments based on recognized peer disagreement and the historical contingency of our beliefs.

According to deontological approaches to justification, we can analyze justification in deontic terms. In this paper, I try to advance the discussion of deontological approaches by applying recent insights in the semantics of deontic modals. Specifically, I use the distinction between weak necessity modals and strong necessity modals to make progress on a question that has received surprisingly little discussion in the literature, namely: ‘What’s the best version of a deontological approach?’ The two most obvious hypotheses are the Permissive View, (...) according to which justified expresses permission, and the Obligatory View, according to which justified expresses some species of obligation. I raise difficulties for both of these hypotheses. In light of these difficulties, I propose a new position, according to which justified expresses a property I call faultlessness, defined as the dual of weak necessity modals. According to this view, an agent is justified in phi-ing iff it’s not the case that she should [/ought] not phi. I argue that this ‘Faultlessness View’ gives us precisely what’s needed to avoid the problems facing the Permissive and Obligatory Views. (shrink)

Suppose you’d like to believe that p, whether or not it’s true. What can you do to help? A natural initial thought is that you could engage in Intentionally Biased Inquiry : you could look into whether p, but do so in a way that you expect to predominantly yield evidence in favour of p. This paper hopes to do two things. The first is to argue that this initial thought is mistaken: intentionally biased inquiry is impossible. The second is (...) to show that reflections on intentionally biased inquiry strongly support a controversial ‘access’ principle which states that, for all p, if p is part of our evidence, then that p is part of our evidence is itself part of our evidence. (shrink)

White, Christensen, and Feldman have recently endorsed uniqueness, the thesis that given the same total evidence, two rational subjects cannot hold different views. Kelly, Schoenfield, and Meacham argue that White and others have at best only supported the weaker, merely intrapersonal view that, given the total evidence, there are no two views which a single rational agent could take. Here, we give a new argument for uniqueness, an argument with deliberate focus on the interpersonal element of the thesis. Our argument (...) is that the best explanation of the value of promoting rationality is an explanation that entails uniqueness. (shrink)

I present an argument against the thesis of Uniqueness and in favour of Permissivism. Counterexamples to Uniqueness are provided, based on ‘Safespot’ propositions – i.e. a proposition that is guaranteed to be true provided the subject adopts a certain attitude towards it. The argument relies on a plausible principle: (roughly stated) If S knows that her believing p would be a true belief, then it is rationally permitted for S to believe p. One motivation for denying this principle – viz. (...) opposition to ‘epistemic consequentialism’ – is briefly discussed. The principle is extended to cover degrees of belief and compared with a couple of other well-known constraints on rational degrees of belief. (shrink)

Conciliationism holds that disagreement of apparent epistemic peers often substantially undermines rational confidence in our opinions. Uniqueness principles say that there is at most one maximally rational doxastic response to any given batch of total evidence. The two views are often thought to be tightly connected. This paper distinguishes two ways of motivating conciliationism, and two ways that conciliationism may be undermined by permissive accounts of rationality. It shows how conciliationism can flourish under certain strongly permissive accounts of rationality. This (...) occurs when the motivation for conciliationism does not come from taking disagreement as evidence of one's own rational failings. However, divorcing the motive for conciliating from worries about rationality does not remove a feature of conciliationism that some find troubling: that conciliationism can lead to cases of “rational toxicity,” in which the most rational response to one's evidence involves violating some rational ideal. (shrink)

This paper has two aims. The first is critical: it argues that our mainstream epistemology of disagreement does not have the resources to explain what goes wrong in cases of group-level epistemic injustice. The second is positive: we argue that a functionalist account of group belief and group justification delivers an account of the epistemic peerhood relation between groups that accommodates minority and oppressed groups, and diagnoses the epistemic injustice cases correctly as cases of unwarranted belief on the part of (...) the oppressor group. (shrink)

On the face of it, in ordinary practices of rational assessment, we criticize agents both for the combinations of attitudes, like belief, desire, and intention, that they possess at particular times, and for the ways that they behave cognitively over time, by forming, reconsidering, and updating those attitudes. Accordingly, philosophers have proposed norms of rationality that are synchronic—concerned fundamentally with our individual time-slices, and diachronic—concerned with our temporally extended behaviour. However, a recent movement in epistemology has cast doubt on the (...) very existence of requirements of the latter type. My aim in this paper is to address what I take to be the most direct and general recent attack on diachronic epistemic rationality, the arguments for so-called ‘time-slice epistemology’ by Brian Hedden. I argue that Hedden's attempt to motivate the rejection of diachronic rational norms ultimately fails, and in particular that an independently attractive view about the nature of such norms, namely one on which such norms govern processes, escapes his assault unscathed. (shrink)

According to doxastic involuntarism, we cannot believe at will. In this paper, I argue that permissivism, the view that, at times, there is more than one way to respond rationally to a given body of evidence, is consistent with doxastic involuntarism. Rober :837–859, 2019a, Philos Phenom Res 1–17, 2019b) argues that, since permissive situations are possible, cognitively healthy agents can believe at will. However, Roeber fails to distinguish between two different arguments for voluntarism, both of which can be shown to (...) fail by proper attention to different accounts of permissivism. Roeber considers a generic treatment of permissivism, but key premises in both arguments depend on different, more particular notions of permissivism. Attending to the distinction between single-agent and inter-subjective versions of permissivism reveals that the inference from permissivism to voluntarism is unwarranted. (shrink)