Belief Revision

How do we acquire beliefs? According to the Spinozan model, merely having a thought entails believing it. Only through a further, effortful process can one reject automatically-accepted beliefs. This paper supersedes and extends previous expositions of the Spinozan model in four ways. First, we introduce the mechanisms of the model, by characterizing the interactions of acceptance, rejection, and endorsement. Second, we present recent developmental and theoretical work that supports the Spinozan model. Third, we draw out some sociopolitical implications of having (...) a Spinozan mind, particularly for fake news and misinformation. Finally, we extend the model from its traditional domain, belief acquisition, to belief updating and action. The result provides the foundation for a psychofunctional model of belief proper. (shrink)

Reasoning that leads to delusions—especially in schizophrenia—appears beyond the bounds of sense, profoundly inaccessible. By analyzing empirical research on reasoning that supports delusions in schizophrenia, I demonstrate that such reasoning can be made intelligible at the personal level. Specifically, I propose that these empirical findings can be positively characterized as reflecting a distinctive epistemic style—a unique implementation of reason rather than its absence. Delusion-supporting reasoning in schizophrenia can be understood as expressing epistemic values and preferences characteristic of a maverick epistemic (...) personality. As such, it is substantially intelligible in light of these underlying values. Further, I argue that the presence of this epistemic style in individuals with schizophrenia can itself be understood in light of their anomalous experiences and social exclusion. This view contributes to reducing stigma and provides new resources for theorizing non-standard interactions with evidence within the neurodiversity paradigm. (shrink)

Dr. Thomas Sowell is a philosophical force. It may surprise some to hear this, given that the man is rarely (if ever) referenced as a philosopher by professional academics. It will be the primary objective of this thesis to systematize a thoroughgoing metaphysics from Sowell’s disparate works, in order to establish that Sowell’s work contains a consistent and rigorous philosophical viewpoint. As a corollary of this fact, it will be demonstrated that Sowell is a philosopher deserving of a place in (...) the contemporary cannon, even though he is currently not regarded as such by most professional philosophers. While much more can be said about Sowell’s social, political, ethical, and wide-ranging epistemological views, this paper will primarily focus on the metaphysical grounding that this other work relies on as its pre-condition. Certain aspects of Sowell’s epistemological work will also be considered, as such pertain to his system of metaphysics. Trained as an economist and famous for his conservative social commentary, Sowell is more than a domain-specific expert in a given field, he’s a systematic thinker who gives a nuanced philosophical account for not only his views, but for the fundamental premises on which they rely. Unfortunately, Sowell currently enjoys little consideration as an academic philosopher, as he does not write in the ecosystem of journals constructed for professional philosophers, nor does his philosophical focus concern itself with much of the contemporary debates in the field. Yet, a philosopher he is by virtue of his work: he writes about what is, how we know it, and what we should do about it. This thesis will systematize Sowell’s metaphysical commitments while explaining a limited portion of his related work on epistemological concerns. With this systemization in place, a straightforward argument follows that he is ultimately a pragmatist philosopher with an account of reality that is consistent and thorough enough to warrant the title. With the above in mind, this thesis aims to make Sowell’s philosophy more concise and accessible to academic philosophers by showing it for the rigorous system that it is. Resultant from this, professional philosophers may be well-advised to make some room in the cannon for Dr. Thomas Sowell. (shrink)

Un fait Mooréen, selon l'expression de David Lewis, est « l'une des choses que nous savons mieux que toute prémisse d'une argumentation philosophique visant à é tablir le contraire. » Le sujet des faits Mooréens soulève des questions profondes, à la fois de méthode philosophique et d'épistémologie de premier ordre. Comment devrions-nous répondre aux arguments qui remettent en question des croyances dont nous sommes extrêmement confiants ? Dans quelle mesure ces arguments – ou plutôt ceux qui les avancent – peuvent-ils (...) espérer avoir une emprise ou une traction rationnelle sur nous ? Dans quelle mesure, si même c'est le cas, notre point de départ limite-t-il les types de révisions de nos croyances que la philosophie pourrait légitimement inspirer ? Quand sommes-nous justifiés (si jamais nous le sommes) à refuser de se laisser influencer par un argument qui, pour autant qu'on puisse en juger, est sans faille, et quand un tel refus relève-t-il simplement du dogmatisme ? Ce sont là de vastes questions, auxquelles je ne tenterai pas ici de répondre complétement. Mon ambition, plus modeste, est de tenter de progresser sur ces questions, et d'autres questions connexes, en examinant la notion de fait Mooré que je trouve chez Lewis et chez d'autres. (shrink)

Standard arguments for Bayesian conditionalizing rely on assumptions that many epistemologists have criticized as being too strong: (i) that conditionalizers must be logically infallible, which rules out the possibility of rational logical learning, and (ii) that what is learned with certainty must be true (factivity). In this paper, we give a new factivity-free argument for the superconditionalization norm in a personal possibility framework that allows agents to learn empirical and logical falsehoods. We then discuss how the resulting framework should be (...) interpreted. Does it still model norms of rationality, or something else, or nothing useful at all? We discuss five ways of interpreting our results, three that embrace them and two that reject them. We find one of each kind wanting, and leave readers to choose among the remaining three. (shrink)

Largely thanks to Mill’s influence, the suggestion that the state ought to restrict the distribution of misinformation will strike most philosophers as implausible. Two of Mill’s influential assumptions are particularly relevant here: first, that free speech debates should focus on moral considerations such as the harm that certain forms of expression might cause; second, that false information causes minimal harm due to the fact that human beings are psychologically well equipped to distinguish truth and falsehood. However, in addition to our (...) moral obligations, we also have a distinct set of epistemic obligations—and even when a false belief doesn’t harm anyone, it constitutes an epistemically bad outcome. Moreover, Mill was profoundly mistaken about human psychology: human beings are vulnerable to the influence of a wide variety of false claims via a wide variety of psychological mechanisms. Consequently, there is a purely epistemic justification for restricting the distribution of misinformation: because each of us has an individual epistemic obligation to avoid unnecessary exposure to misinformation, and because avoiding such exposure is simply too difficult when acting alone, we all have a shared epistemic obligation to establish laws or regulations restricting the widespread distribution of misinformation. (shrink)

This paper aims to shed light on the nature of belief and provide support to the view that I call ‘Minimalism’. It shows that Minimalism is better equipped than the traditional approach to separating belief from imagination and addressing cases of belief’s evidence- resistance. The key claim of the paper is that no matter how epistemically irrational humans’ beliefs are, they always retain a minimal level of rationality.

According to the cognitive model of psychopathology, maladaptive beliefs about oneself, others, and the world are the main factors contributing to the development and persistence of various forms of mental suffering. Therefore, the key therapeutic process of Cognitive Behavioral Therapy (CBT)—a therapeutic approach rooted in the cognitive model—is cognitive restructuring, i.e., a process of revision of such maladaptive beliefs. In this paper, I examine the philosophical assumptions underlying CBT and offer theoretical reasons to think that the effectiveness of belief revision (...) in psychotherapy is very limited. This is the case, I argue, because the cognitive model wrongly assumes that our body of beliefs is unified, while it is in fact fragmented. (shrink)

Beliefs can be resistant to evidence. Nonetheless, the orthodox view in epistemology analyzes beliefs as evidence-responsive attitudes. I address this tension by deploying analytical tools on capacities and masking to show that the cognitive science of evidence-resistance supports rather than undermines the orthodox view. In doing so, I argue for the claim that belief requires the capacity for evidence-responsiveness. More precisely, if a subject believes that p, then they have the capacity to rationally respond to evidence bearing on p. Because (...) capacities for evidence-responsiveness are fallible and may be masked, beliefs can be held in the face of counter-evidence. Indeed, I will argue that our best science of belief supports the claim that evidence-resistant beliefs result from masks on evidence-responsiveness capacities. This account of belief not only allows for resistance to evidence, but provides us with a framework for describing and explaining actual cases of evidence-resistance. (shrink)

A large body of work has demonstrated the utility of the Bayesian framework for capturing inference in both specialist and everyday contexts. However, the central tool of the framework, conditionalization via Bayes’ rule, does not apply directly to a common type of learning: the acquisition of conditional information. How should an agent change her beliefs on learning that “If A, then C”? This issue, which is central to both reasoning and argumentation, has recently prompted considerable research interest. In this paper, (...) we critique a prominent proposal and provide a new, alternative, answer. -/- . (shrink)

In “Regulating social media as a public good: Limiting epistemic segregation” (2022), Toby Handfield tackles a well-known problematic aspect of widespread social media use: the formation of ideologically monotone and insulated social networks. Handfield argues that we can take some cues from economics to reduce the extent to which echo chambers grow up around individual users. Specifically, he argues that tax incentives to encourage network heterophily may be levied at any of three different groups: individual social media users, social media (...) sites/companies, or advertisers who use social media to promote their products and material. In this response, I examine the plausibility of using such incentives on each of the these groups. I argue, first, that using tax incentives on either (1) social media companies or (2) advertisers would be ineffective as these incentives could not feasibly be made strong enough to override the enormous financial gain of the standard social media algorithms. Next, I argue that levying the incentives/penalties on individual users would be a hazard, due to the risk of what is called the epistemic “backfire effect”. Finally, I argue that the problem lies in relying on incentives and disincentives—rather than direct regulation—to increase network heterophily. (shrink)

We offer two arguments against the halving repose to Sleeping Beauty. First, we show that halving violates the Epistemological Sure-Thing Principle, which we argue is a necessary constraint on any reasonable probability assignment. The constraint is that if hypothetically on C you assign to A the same probability you assign to A hypothetical on not-C, you must assign that probability to A simpliciter. Epistemically, it's a sure thing for you that A has this probability. Second, we show that halving violates (...) solid statistical reasoning (or draws absurdly irrelevant distinctions). (shrink)

This paper challenges the conventional wisdom dominating the social sciences and philosophy regarding temporal discounting, the practice of discounting the value of future utility when making decisions. Although there are sharp disagreements about temporal discounting, a kind of standard model has arisen, one that begins with a normative standard about how we should make intertemporal comparisons of utility. This standard demands that in so far as one is rational one discounts utilities at future times with an exponential discount function. Tracing (...) the justification for this standard through economics, philosophy and psychology, I’ll make what I believe is the best case one can for it, showing how a non-arbitrariness assumption and a dominance argument together imply that discounting ought to be exponential. Ultimately, however, I don’t find the case compelling. Non-exponential temporal discounting is often rational. If this is correct, Instead of trying to ‘fix’ non-exponential discounting because it is irrational and associated with negative life outcomes, we might instead focus attention on why the conditions obtain that make such discounting rational. (shrink)

James Joyce's article “A Nonpragmatic Vindication of Probabilism” introduced an approach to arguing for credal norms by appealing to the epistemic value of accuracy. The central thought was that credences ought to accurately represent the world, a guiding thought that has gone on to generate an entire research paradigm on the rationality of credences. Recently, a number of epistemologists have begun to apply this same thought to full beliefs, attempting to explain and argue for norms of belief in terms of (...) epistemic value. This paper examines these recent attempts, showing how they interact with work on the accuracy of credences. It then examines how differing judgments about epistemic value give rise to distinct rational requirements for belief, concluding by considering some of the fundamental questions and issues yet to be fully explored. (shrink)

The study of belief is expanding and involves a growing set of disciplines and research areas. These research programs attempt to shed light on the process of believing, understood as a central human cognitive function. Computational systems and, in particular, what we commonly understand as Artificial Intelligence (AI), can provide some insights on how beliefs work as either a linear process or as a complex system. However, the computational approach has undergone some scrutiny, in particular about the differences between what (...) is distinctively human and what can be inferred from AI systems. The present article investigates to what extent recent developments in AI provide new elements to the debate and clarify the process of belief acquisition, consolidation, and recalibration. The article analyses and debates current issues and topics of investigation such as: different models to understand belief, the exploration of belief in an automated reasoning environment, the case of religious beliefs, and future directions of research. (shrink)

When one thinks—knows, believes, imagines—that something is the case, one’s thought has a topic: it is about something, towards which one’s mind is directed. What is the logic of thought, so understood? This book begins to explore the idea that, to answer the question, we should take topics seriously. It proposes a hyperintensional account of the propositional contents of thought, arguing that these are individuated not only by the set of possible worlds at which they are true, but also by (...) their topic: what they are about. The book then builds epistemic, doxastic, probabilistic, and conditional logics based on this view. It applies them to issues ranging from dogmatism, scepticism, and epistemic fallibilism, to imagination and suppositional reasoning, belief revision, framing effects, and the acceptability of indicative conditionals. (shrink)

Epistemic agents interact with evidence in different ways. This can cause trouble for mutual understanding and for our ability to rationally engage with others. Indeed, it can compromise democratic practices of deliberation. This paper explains these differences by appeal to a new notion: epistemic styles. Epistemic styles are ways of interacting with evidence that express unified sets of epistemic values, preferences, goals, and interests. The paper introduces the notion of epistemic styles and develops a systematic account of their nature. It (...) then discusses the implications of epistemic styles for central questions in epistemology, in particular, for issues surrounding rational engagement and for the debate between virtue epistemologists and epistemic situationists. (shrink)

I discuss voluntary belief in the context of a phenomenon unique to our current political moment: self- brainwashing. Using the very public QAnon movement as a case study, I argue that, although the conditions in which QAnon beliefs are formed is highly similar to those that produce false confessions, the QAnon believer and not the false confessor is morally and epistemically responsible because the former’s beliefs are voluntary: belief is voluntary when the believer has both the capacity and the opportunity (...) to revise their belief. I conclude that this voluntariness is because of the uniquely distributed, Internet-based nature of QAnon. (shrink)

We argue that social deliberation may increase an agent’s confidence and credence under certain circumstances. An agent considers a proposition H and assigns a probability to it. However, she is not fully confident that she herself is reliable in this assignment. She then endorses H during deliberation with another person, expecting him to raise serious objections. To her surprise, however, the other person does not raise any objections to H. How should her attitudes toward H change? It seems plausible that (...) she should increase the credence she assigns to H and, at the same time, increase the reliability she assigns to herself concerning H. A Bayesian model helps us to investigate under what conditions, if any, this is rational. (shrink)

It is often claimed that epistemic bubbles and echo chambers foster post-truth by filtering our access to information and manipulating our epistemic attitude. In this paper, I try to add a further level of analysis by adding the issue of belief formation. Building on cognitive psychology work, I argue for a dual-system theory according to which beliefs derive from a default system and a critical system. One produces beliefs in a quasi-automatic, effortless way, the other in a slow, effortful way. (...) I also argue that digital socio-epistemic environments tend to inculcate disvalues in their agent's epistemic identity, a process that causes the cognitive shortcircuits typical of conspiracy theories. (shrink)

This paper briefly outlines some advancements in paraconsistent logics for modelling knowledge representation and reasoning. Emphasis is given on the so-called Logics of Formal Inconsistency (LFIs), a class of paraconsistent logics that formally internalize the very concept(s) of consistency and inconsistency. A couple of specialized systems based on the LFIs will be reviewed, including belief revision and probabilistic reasoning. Potential applications of those systems in the AI area of KRR are tackled by illustrating some examples that emphasizes the importance of (...) a fine-tuned treatment of consistency in modelling reputation systems, preferences, argumentation, and evidence. (shrink)

By Belief Revision it is understood a system that logically explains the rational process of changing beliefs by taking into account a new piece of information. The most influential approach in this field of study, the AGM system, proposed by Alchourrón, Gärdenfors, and Makinson, postulates rationality criteria for different types of belief change. In this paper I shall assess the relationship between those criteria and argue for an opposition between the principles of Information Economy and Consistency. Furthermore, I shall argue (...) that Paraconsistent Belief Revision manages to minimise this friction in the best possible way. (shrink)

Politics is rife with motivated cognition. People do not dispassionately engage with the evidence when they form political beliefs; they interpret it selectively, generating justifications for their desired conclusions and reasons why contrary evidence should be ignored. Moreover, research shows that epistemic ability (e.g. intelligence and familiarity with evidence) is correlated with motivated cognition. Bjørn Hallsson has pointed out that this raises a puzzle for the epistemology of disagreement. On the one hand, we typically think that epistemic ability in an (...) interlocutor gives us reason to downgrade our belief upon learning that we disagree. On the other hand, if our interlocutor is under the sway of motivated cognition, then we have reason to discount his opinion. In this paper, I argue that Hallsson's puzzle is solved by adopting a Bayesian approach to disagreement. If an interlocutor is under the sway of motivated cognition, his disagreement should not affect our beliefs--no matter his ability. Because we implicitly and to high accuracy know his beliefs before he reveals them to us, disagreement provides us with no new information on which to conditionalize. I advance a model which accommodates the motivated cognition dynamic and other key epistemic features of disagreement. (shrink)

Caracterizando a existência como um processo de escolha e decisão que converge para a constituição do sujeito como tal, Kierkegaard atribui à existência a condição de um projeto em uma construção que encerra três possibilidades existenciais fundamentais, a saber, o estético, o ético e o religioso. Dessa forma, o artigo assinala que, constituindo-se uma dimensão em cujo estádio a procura do sentido ou a busca do absoluto circunscreve-se à imanência, o modo existencial estético caracteriza-se como a fruição da subjetividade consigo (...) própria através do instante do prazer sensual em um movimento que implica a sedução como esforço de conquista de si que, contudo, escapa ao seu poder em uma relação que converge para o desespero, haja vista que a renovação de forma indefinida da condição originária do amor esgota-se na generalização. E se o estágio ético encerra a integração na comunidade social através da institucionalização da repetição como um modo de vida baseado na objetividade e na racionalidade, a conformação do sujeito ao modus vivendi e ao modus essendi do geral implica a harmonização da sua subjetividade com a generalidade do bem e do mal por meio de um processo que torna-se incapaz de resolver a questão da sua desordem existencial. Assim sendo, o artigo mostra que, se a virtude moral que o ético impõe converge para a impossibilidade de superação do desespero que caracteriza a busca do absoluto na imanência, a atitude religiosa, abdicando da realidade em sua totalidade finita em função da relação absoluta com o Absoluto, demanda a suspensão teleológica do ético e tende a instaurar a autenticidade existencial através de um movimento que mantém correspondência com a fé como o “salto” que implica a consciência de si em sua singularidade e a espiritualidade individual. (shrink)

This paper considers a problem for Bayesian epistemology and proposes a solution to it. On the traditional Bayesian framework, an agent updates her beliefs by Bayesian conditioning, a rule that tells her how to revise her beliefs whenever she gets evidence that she holds with certainty. In order to extend the framework to a wider range of cases, Jeffrey (1965) proposed a more liberal version of this rule that has Bayesian conditioning as a special case. Jeffrey conditioning is a rule (...) that tells the agent how to revise her beliefs whenever she gets evidence that she holds with any degree of confidence. The problem? While Bayesian conditioning has a foundationalist structure, this foundationalism disappears once we move to Jeffrey conditioning. If Bayesian conditioning is a special case of Jeffrey conditioning, then they should have the same normative structure. The solution? To reinterpret Bayesian updating as a form of diachronic coherentism. (shrink)

I argue that bounded agents face a systematic accuracy-coherence tradeoff in cognition. Agents must choose whether to structure their cognition in ways likely to promote coherence or accuracy. I illustrate the accuracy-coherence tradeoff by showing how it arises out of at least two component tradeoffs: a coherence-complexity tradeoff between coherence and cognitive complexity, and a coherence-variety tradeoff between coherence and strategic variety. These tradeoffs give rise to an accuracy-coherence tradeoff because privileging coherence over complexity or strategic variety often leads to (...) a corresponding reduction in accuracy. I conclude with a discussion of two normative consequences for the study of bounded rationality: the importance of procedural rationality and the role of coherence in theories of bounded rationality. (shrink)

Suppositional theories of conditionals take apparent similarities between supposition and conditionals as a starting point, appealing to features of the former to provide an account of the latter. This paper develops a novel form of suppositional theory, one which characterizes the relationship at the level of semantics rather than at the level of speech acts. In the course of doing so, it considers a range of novel data which shed additional light on how conditionals and supposition interact.

Can perceptual experiences be states of uncertainty? We might expect them to be, if the perceptual processes from which they're generated, as well as the behaviors they help produce, take account of probabilistic information. Yet it has long been presumed that perceptual experiences purport to tell us about our environment, without hedging or qualifying. Against this long-standing view, I argue that perceptual experiences may well occasionally be states of uncertainty, but that they are never probabilistically structured. I criticize a powerful (...) line of reasoning that we should expect perceptual experience to be probabilistic, given their interfaces with unconscious probabilistic information, with behavior responsive to it, and with credences. (shrink)

I explore how rational belief and rational credence relate to evidence. I begin by looking at three cases where rational belief and credence seem to respond differently to evidence: cases of naked statistical evidence, lotteries, and hedged assertions. I consider an explanation for these cases, namely, that one ought not form beliefs on the basis of statistical evidence alone, and raise worries for this view. Then, I suggest another view that explains how belief and credence relate to evidence. My view (...) focuses on the possibilities that the evidence makes salient. I argue that this makes better sense of the difference between rational credence and rational belief than other accounts. (shrink)

When an agent learns of an expert's credence in a proposition about which they are an expert, the agent should defer to the expert and adopt that credence as their own. This is a popular thought about how agents ought to respond to (ideal) experts. In a Bayesian framework, it is often modelled by endowing the agent with a set of priors that achieves this result. But this model faces a number of challenges, especially when applied to non-ideal agents (who (...) nevertheless interact with ideal experts). I outline these problems, and use them as desiderata for the development of a new model. Taking inspiration from Richard Jeffrey's development of Jeffrey conditioning, I develop a model in which expert reports are taken as exogenous constraints on the agent's posterior probabilities. I show how this model can handle a much wider class of expert reports (for example reports of conditional probabilities), and can be naturally extended to cover propositions for which the agent has no prior. (shrink)

The logic of indicative conditionals remains the topic of deep and intractable philosophical disagreement. I show that two influential epistemic norms—the Lockean theory of belief and the Ramsey test for conditional belief—are jointly sufficient to ground a powerful new argument for a particular conception of the logic of indicative conditionals. Specifically, the argument demonstrates, contrary to the received historical narrative, that there is a real sense in which Stalnaker’s semantics for the indicative did succeed in capturing the logic of the (...) Ramseyan indicative conditional. (shrink)

Suppositions can be introduced in either the indicative or subjunctive mood. The introduction of either type of supposition initiates judgments that may be either qualitative, binary judgments about whether a given proposition is acceptable or quantitative, numerical ones about how acceptable it is. As such, accounts of qualitative/quantitative judgment under indicative/subjunctive supposition have been developed in the literature. We explore these four different types of theories by systematically explicating the relationships canonical representatives of each. Our representative qualitative accounts of indicative (...) and subjunctive supposition are based on the belief change operations provided by AGM revision and KM update respectively; our representative quantitative ones are offered by conditionalization and imaging. This choice is motivated by the familiar approach of understanding supposition as `provisional belief revision' wherein one temporarily treats the supposition as true and forms judgments by making appropriate changes to their other opinions. To compare the numerical judgments recommended by the quantitative theories with the binary ones recommended by the qualitative accounts, we rely on a suitably adapted version of the Lockean thesis. Ultimately, we establish a number of new results that we interpret as vindicating the often-repeated claim that conditionalization is a probabilistic version of revision, while imaging is a probabilistic version of update. (shrink)

The problem of old evidence, first described by Glymour [1980], is still widely regarded as one of the most pressing foundational challenges to the Bayesian account of scientific reasoning. Many solutions have been proposed, but all of them have drawbacks and none is considered to be definitive. Here, we introduce and defend a new kind of solution, according to which hypotheses are confirmed when we become more confident that they provide the only way of accounting for the known evidence.

The Bayesian maxim for rational learning could be described as conservative change from one probabilistic belief or credence function to another in response to newinformation. Roughly: ‘Hold fixed any credences that are not directly affected by the learning experience.’ This is precisely articulated for the case when we learn that some proposition that we had previously entertained is indeed true (the rule of conditionalisation). But can this conservative-change maxim be extended to revising one’s credences in response to entertaining propositions or (...) concepts of which one was previously unaware? The economists Karni and Vierø (2013, 2015) make a proposal in this spirit. Philosophers have adopted effectively the same rule: revision in response to growing awareness should not affect the relative probabilities of propositions in one’s ‘old’ epistemic state. The rule is compelling, but only under the assumptions that its advocates introduce. It is not a general requirement of rationality, or so we argue. We provide informal counterexamples. And we show that, when awareness grows, the boundary between one’s ‘old’ and ‘new’ epistemic commitments is blurred. Accordingly, there is no general notion of conservative change in this setting. (shrink)

In this article, we address a major outstanding question of probabilistic Bayesian epistemology: how should a rational Bayesian agent update their beliefs upon learning an indicative conditional? A number of authors have recently contended that this question is fundamentally underdetermined by Bayesian norms, and hence that there is no single update procedure that rational agents are obliged to follow upon learning an indicative conditional. Here we resist this trend and argue that a core set of widely accepted Bayesian norms is (...) sufficient to identify a normatively privileged updating procedure for this kind of learning. Along the way, we justify a privileged formalization of the notion of ‘epistemic conservativity’, offer a new analysis of the Judy Benjamin problem, and emphasize the distinction between interpreting the content of new evidence and updating one’s beliefs on the basis of that content. (shrink)

Four intuitions are recurrent and influential in theories about conditionals: the Ramsey’s test, the Adams’ Thesis, the Equation, and the robustness requirement. For simplicity’s sake, I call these intuitions ‘the big four’. My aim is to show that: (1) the big four are interdependent; (2) they express our inferential dispositions to employ a conditional on a modus ponens; (3) the disposition to employ conditionals on a modus ponens doesn’t have the epistemic significance that is usually attributed to it, since the (...) acceptability or truth conditions of a conditional is not necessarily associated with its employability on a modus ponens. (shrink)

Disagreement is a ubiquitous feature of human life, and philosophers have dutifully attended to it. One important question related to disagreement is epistemological: How does a rational person change her beliefs (if at all) in light of disagreement from others? The typical methodology for answering this question is to endorse a steadfast or conciliatory disagreement norm (and not both) on a priori grounds and selected intuitive cases. In this paper, I argue that this methodology is misguided. Instead, a thoroughgoingly Bayesian (...) strategy is what's needed. Such a strategy provides conciliatory norms in appropriate cases and steadfast norms in appropriate cases. I argue, further, that the few extant efforts to address disagreement in the Bayesian spirit are laudable but uncompelling. A modelling, rather than a functional, approach gets us the right norms and is highly general, allowing the epistemologist to deal with (1) multiple epistemic interlocutors, (2) epistemic superiors and inferiors (i.e. not just epistemic peers), and (3) dependence between interlocutors. (shrink)

I explore the possibility and rationality of interpersonal mechanisms of doxastic self-control, that is, ways in which individuals can make use of other people in order to get themselves to stick to their beliefs. I look, in particular, at two ways in which people can make interpersonal epistemic commitments, and thereby willingly undertake accountability to others, in order to get themselves to maintain their beliefs in the face of anticipated “epistemic temptations”. The first way is through the avowal of belief, (...) and the second is through the establishment of collective belief. I argue that both of these forms of interpersonal epistemic commitment can function as effective tools for doxastic self-control, and, moreover, that the control they facilitate should not be dismissed as irrational from an epistemic perspective. (shrink)

The present paper wants to promote epistemic pluralism as an alternative view of non-classical logics. For this purpose, a bilateralist logic of acceptance and rejection is developed in order to make an important di erence between several concepts of epistemology, including information and justi cation. Moreover, the notion of disagreement corresponds to a set of epistemic oppositions between agents. The result is a non-standard theory of opposition for many-valued logics, rendering total and partial disagreement in terms of epistemic negation and (...) semi-negations. (shrink)

There is consensus among computer scientists, logicians, and philosophers that good reasoning with qualitative beliefs must have the structural property of cumulative transitivity or, for short, cut. This consensus is typically explicitly argued for partially on the basis of practical and mathematical considerations. But the consensus is also implicit in the approach philosophers take to almost every puzzle about reasoning that involves multiple steps: philosophers typically assume that if each step in reasoning is acceptable considered on its own, the whole (...) chain of reasoning must also acceptable. In this paper I focus on whether there are good philosophical reasons for thinking that the consensus that good reasoning must satisfy cut is true. My central claim is that we should not accept the consensus—good reasoning might not satisfy cut. In particular, I consider four arguments for the consensus and explain why they are unpersuasive. (§2-5). I then show that the issue of whether good reasoning is cut turns on a substantive yet until now unnoticed question in epistemology (§6). (shrink)

This symposium in the overlap of philosophy and decision theory is described well by its title “Beliefs in Groups”. Each word in the title matters, with one intended ambiguity. The symposium is about beliefs rather than other attitudes such as preferences; these beliefs take the form of probabilities in the first three contributions, binary yes/no beliefs (‘judgments’) in the fourth contribution, and qualitative probabilities (‘probability grades’) in the fifth contribution. The beliefs occur in groups, which is ambiguous between beliefs of (...) groups as a whole and beliefs of group members. The five contributions – all of them interesting, we believe – address several aspects of this general theme. (shrink)

We often hear such casual accusations: you just believe that because you are a liberal, a Christian, an American, a woman… When such charges are made they are meant to sting—not just emotionally, but epistemically. But should they? It can be disturbing to learn that one's beliefs reflect the influence of such irrelevant factors. The pervasiveness of such influence has led some to worry that we are not justified in many of our beliefs. That same pervasiveness has led others to (...) doubt whether there is any worry here at all. I argue that evidence of irrelevant belief influence is sometimes, but not always, undermining. My proposal picks out ordinary, non-skeptical cases in which we get evidence of error. It says that, in those cases, evidence of irrelevant influence is epistemically significant. It shows how respecting evidence of error is compatible with the epistemic lives we see ourselves living. We are fallible creatures, yes, but we are also capable and intelligent ones. We can recognize and correct for our own error so as to improve our imperfect, yet nevertheless robust, epistemic lives. (shrink)

After a number of decades of research into the dynamics of rational belief, the belief revision theory community remains split on the appropriate handling of sequences of changes in view, the issue of so-called iterated revision. It has long been suggested that the matter is at least partly settled by facts pertaining to the results of various single revisions of one’s initial state of belief. Recent work has pushed this thesis further, offering various strong principles that ultimately result in a (...) wholesale reduction of iterated to one-shot revision. The present paper offers grounds to hold that these principles should be significantly weakened and that the reductionist thesis should ultimately be rejected. Furthermore, the considerations provided suggest a close connection between the logic of iterated belief change and the logic of evidential relevance. (shrink)

The paper proposes two logical analyses of (the norms of) justification. In a first, realist-minded case, truth is logically independent from justification and leads to a pragmatic logic LP including two epistemic and pragmatic operators, namely, assertion and hypothesis. In a second, antirealist-minded case, truth is not logically independent from justification and results in two logical systems of information and justification: AR4 and AR4¢, respectively, provided with a question-answer semantics. The latter proposes many more epistemic agents, each corresponding to a (...) wide variety of epistemic norms. After comparing the different norms of justification involved in these logical systems, two hexagons expressing Aristotelian relations of opposition will be gathered in order to clarify how (a fragment of) pragmatic formulas can be interpreted in a fuzzy-based question-answer semantics. (shrink)

People often act in ways that appear incompatible with their sincere assertions. But how might we explain such cases? On the shifting view, subjects’ degrees of belief may be highly sensitive to changes in context. This paper articulates and refines this view, after defending it against recent criticisms. It details two mechanisms by which degrees of beliefs may shift.

We present a general framework for representing belief-revision rules and use it to characterize Bayes's rule as a classical example and Jeffrey's rule as a non-classical one. In Jeffrey's rule, the input to a belief revision is not simply the information that some event has occurred, as in Bayes's rule, but a new assignment of probabilities to some events. Despite their differences, Bayes's and Jeffrey's rules can be characterized in terms of the same axioms: "responsiveness", which requires that revised beliefs (...) incorporate what has been learnt, and "conservativeness", which requires that beliefs on which the learnt input is "silent" do not change. To illustrate the use of non-Bayesian belief revision in economic theory, we sketch a simple decision-theoretic application. (shrink)

Context has emerged as a central concept in a variety of contemporary approaches to reasoning. The conference at which the papers in this volume were presented, CONTEXT 2001, was the third international, interdisciplinary conference on the topic of context, and was held in Dundee, Scotland on July 27-30, 2001.

We discuss various possibilities for developing a dynamic doxastic logic (DDL) for introspective agents: agents who have the ability to form higher-order beliefs. Such agents can reflect upon and change their minds about their own beliefs. The project of constructing such a logic, full DDL or DDL unlimited, is ridden with difficulties due to the fact that the agent's own doxastic state now becomes a part of the reality he is trying to explore. When an introspective agent learns more about (...) the world (and himself), the reality he holds beliefs about undergoes a change in its doxastic part, which means that his introspective beliefs have to be adjusted accordingly. (shrink)