Psychological studies show that the beliefs of two agents in a hypothesis can diverge even if both agents receive the same evidence. This phenomenon of belief polarisation is often explained by invoking biased assimilation of evidence, where the agents’ prior views about the hypothesis affect the way they process the evidence. We suggest, using a Bayesian model, that even if such influence is excluded, belief polarisation can still arise by another mechanism. This alternative mechanism involves differential weighting of the evidence (...) arising when agents have different initial views about the reliability of their sources of evidence. We provide a systematic exploration of the conditions for belief polarisation in Bayesian models which incorporate opinions about source reliability, and we discuss some implications of our findings for the psychological literature. (shrink)

Belief polarization occurs when subjects who disagree about some matter of fact are exposed to a mixed body of evidence that bears on that dispute. While we might expect mutual exposure to common evidence to mitigate disagreement, since the evidence available to subjects comes to consist increasingly of items they have in common, this is not what happens. The subjects’ initial disagreement becomes more pronounced because each person increases confidence in her antecedent belief. Kelly aims to identify the mechanisms that (...) underlie this phenomenon and assess whether these processes undermine the justification of polarized beliefs. He concludes that given evidentialism, justification is not undermined by the polarizing mechanisms. I take on board Kelly’s description of the polarizing mechanisms, but challenge his conclusion. I argue that on plausible versions of evidentialism, the beliefs that result from these routes to polarization are not justified. (shrink)

In this paper, I defend the view that it is wrong for us to consume only, or overwhelmingly, media that broadly aligns with our own political viewpoints: that is, it is wrong to be politically “partisan” in our decisions about what media to consume. We are obligated to consume media that aligns with political viewpoints other than our own – to “diversify our sources”. This is so even if our own views are, as a matter of fact, substantively correct.

Recently, there has been growing concern that increased partisanship in news sources, as well as new ways in which people acquire information, has led to a proliferation of epistemic bubbles and echo chambers: in the former, one tends to acquire information from a limited range of sources, ones that generally support the kinds of beliefs that one already has, while the latter function in the same way, but possess the additional characteristic that certain beliefs are actively reinforced. Here I argue, (...) first, that we should conceive of epistemic bubbles and echo chambers as types of epistemically pernicious groups, and second, that while analyses of such groups have typically focused on relationships between individual members, at least part of what such groups epistemically pernicious pertains to the way that members rely on the groups themselves as sources of information. I argue that member reliance on groups results in groups being attributed a degree of credibility that outruns their warrant, a process I call groupstrapping. I argue that by recognizing the groupstrapping as an illicit method of forming and updating beliefs we can make progress on some of the open questions concerning epistemically pernicious groups. (shrink)

Recent conversation has blurred two very different social epistemic phenomena: echo chambers and epistemic bubbles. Members of epistemic bubbles merely lack exposure to relevant information and arguments. Members of echo chambers, on the other hand, have been brought to systematically distrust all outside sources. In epistemic bubbles, other voices are not heard; in echo chambers, other voices are actively undermined. It is crucial to keep these phenomena distinct. First, echo chambers can explain the post-truth phenomena in a way that epistemic (...) bubbles cannot. Second, each type of structure requires a distinct intervention. Mere exposure to evidence can shatter an epistemic bubble, but may actually reinforce an echo chamber. Finally, echo chambers are much harder to escape. Once in their grip, an agent may act with epistemic virtue, but social context will pervert those actions. Escape from an echo chamber may require a radical rebooting of one's belief system. (shrink)

Beliefs can cause moral wrongs, no doubt, but can they also constitute moral wrongs in their own right? This paper offers some grounds to be skeptical of the idea that there are moral norms which operate directly on belief, independently of any epistemic norms also operating on belief. The resultant skepticism is moderate in the following sense: it holds that the motivations underlying the doxastic morality approach should not be dismissed lightly; they are genuine insights and serve to bring to (...) light important new issues concerning the interaction between our notions of moral and epistemic responsibility. Nonetheless, it is also skeptical, in holding that these concerns are ultimately best voiced in more traditional categories which distinguish the epistemology of belief from the morality of action. (shrink)

Overwhelmingly, philosophers tend to work on the assumption that epistemic justification is a normative status that supervenes on the relation between a cognitive subject, some body of evidence, and a particular proposition (or “hypothesis”). This article will explore some motivations for moving in the direction of a rather different view. On this view, we are invited to think of the relevant epistemic norm(s) as applying more widely to the competent exercise of epistemic agency, where it is understood that cognitive subjects (...) are simultaneously engaged in a number of different epistemic pursuits (distinct “lines of inquiry”), each placing irreconcilable demands on our limited cognitive resources. In effect, adopting this view would require shifting our normative epistemic concern away from the question of how a subject stands with respect to the evidence bearing on the hypothesis at stake in any one line of inquiry, and over onto the question of how well they cope with the inherent risks of epistemic resource management across several lines of inquiry. While this conclusion brings to light important connections between practical and epistemic rationality, it does not collapse the distinction between them. It does, however, constitute a step in the direction of a more systematically developed account of “non-ideal epistemology.”. (shrink)

For two ideally rational agents, does learning a finite amount of shared evidence necessitate agreement? No. But does it at least guard against belief polarization, the case in which their opinions get further apart? No. OK, but are rational agents guaranteed to avoid polarization if they have access to an infinite, increasing stream of shared evidence? No.

Public discussions of political and social issues are often characterized by deep and persistent polarization. In social psychology, it’s standard to treat belief polarization as the product of epistemic irrationality. In contrast, we argue that the persistent disagreement that grounds political and social polarization can be produced by epistemically rational agents, when those agents have limited cognitive resources. Using an agent-based model of group deliberation, we show that groups of deliberating agents using coherence-based strategies for managing their limited resources tend (...) to polarize into different subgroups. We argue that using that strategy is epistemically rational for limited agents. So even though group polarization looks like it must be the product of human irrationality, polarization can be the result of fully rational deliberation with natural human limitations. (shrink)

I propose to study one problem for epistemic dependence on experts: how to locate experts on what I will call cognitive islands. Cognitive islands are those domains for knowledge in which expertise is required to evaluate other experts. They exist under two conditions: first, that there is no test for expertise available to the inexpert; and second, that the domain is not linked to another domain with such a test. Cognitive islands are the places where we have the fewest resources (...) for evaluating experts, which makes our expert dependences particularly risky. -/- Some have argued that cognitive islands lead to the complete unusability of expert testimony: that anybody who needs expert advice on a cognitive island will be entirely unable to find it. I argue against this radical form of pessimism, but propose a more moderate alternative. I demonstrate that we have some resources for finding experts on cognitive islands, but that cognitive islands leave us vulnerable to an epistemic trap which I will call runaway echo chambers. In a runaway echo chamber, our inexpertise may lead us to pick out bad experts, which will simply reinforce our mistaken beliefs and sensibilities. (shrink)

One of Mill’s main arguments for free speech springs from taking disagreement as an epistemically valuable resource for fallible thinkers. Contemporary conciliationist treatments of disagreement spring from the same motivation, but end up seeing the epistemic implications of disagreement quite differently. Conciliationism also encounters complexities when transposed from the 2-person toy examples featured in the literature to the public disagreements among groups that give the issue much of its urgency. Group disagreements turn out to be in some ways more powerful (...) defeaters of rational belief, even when opposing groups are comparable in size and epistemic credentials. And conciliationism also shows us why determining the rational response to these disagreements can in certain cases (e.g. politics) be a particularly difficult and nuanced matter. (shrink)

Recent authors have drawn attention to a new kind of defeating evidence commonly referred to as higher-order evidence. Such evidence works by inducing doubts that one’s doxastic state is the result of a flawed process – for instance, a process brought about by a reason-distorting drug. I argue that accommodating defeat by higher-order evidence requires a two-tiered theory of justification, and that the phenomenon gives rise to a puzzle. The puzzle is that at least in some situations involving higher-order defeaters (...) the correct epistemic rules issue conflicting recommendations. For instance, a subject ought to believe p, but she ought also to suspend judgment in p. I discuss three responses. The first resists the puzzle by arguing that there is only one correct epistemic rule, an Über-rule. The second accepts that there are genuine epistemic dilemmas. The third appeals to a hierarchy or ordering of correct epistemic rules. I spell out problems for all of these responses. I conclude that the right lesson to draw from the puzzle is that a state can be epistemically rational or justified even if one has what looks to be strong evidence to think that it is not. As such, the considerations put forth constitute a non question-begging argument for a kind of externalism. (shrink)

According to a common view, prejudice always involves some form of epistemic culpability, i.e., a failure to respond to evidence in the appropriate way. I argue that the common view wrongfully assumes that prejudices always involve universal generalizations. After motivating the more plausible thesis that prejudices typically involve a species of generic judgment, I show that standard examples provide no grounds for positing a strong connection between prejudice and epistemic culpability. More generally, the common view fails to recognize the extent (...) to which prejudices are epistemically insidious: once they are internalized as background beliefs, they quite reasonably come to control the assessment and interpretation of new evidence. This property of insidiousness helps explain why prejudices are so recalcitrant to empirical counterevidence and also why they are frequently invisible to introspective reflection. (shrink)

Sometimes we get evidence of our own epistemic malfunction. This can come from finding out we’re fatigued, or have been drugged, or that other competent and well-informed thinkers disagree with our beliefs. This sort of evidence seems to seems to behave differently from ordinary evidence about the world. In particular, getting such evidence can put agents in a position where the most rational response involves violating some epistemic ideal.

How much should your confidence in your beliefs be shaken when you learn that others – perhaps 'epistemic peers' who seem as well-qualified as you are – hold beliefs contrary to yours? This article describes motivations that push different philosophers towards opposite answers to this question. It identifies a key theoretical principle that divides current writers on the epistemology of disagreement. It then examines arguments bearing on that principle, and on the wider issue. It ends by describing some outstanding questions (...) that thinking about this issue raises. (shrink)

Suppose that you and I disagree about some non-straightforward matter of fact (say, about whether capital punishment tends to have a deterrent effect on crime). Psychologists have demonstrated the following striking phenomenon: if you and I are subsequently exposed to a mixed body of evidence that bears on the question, doing so tends to increase the extent of our initial disagreement. That is, in response to exactly the same evidence, each of us grows increasingly confident of his or her original (...) view; we thus become increasingly polarized as our common evidence increases. I consider several alternative models of how people reason about newly-acquired evidence which seems to disconfirm their prior beliefs. I then explore the normative implications of these models for the phenomenon in question. (shrink)

A rational person doesn’t believe just anything. There are limits on what it is rational to believe. How wide are these limits? That’s the main question that interests me here. But a secondary question immediately arises: What factors impose these limits? A first stab is to say that one’s evidence determines what it is epistemically permissible for one to believe. Many will claim that there are further, non-evidentiary factors relevant to the epistemic rationality of belief. I will be ignoring the (...) details of alternative answers in order to focus on the question of what kind of rational constraints one’s evidence puts on belief. Our main question concerns how far epistemic permission and obligation can come apart.1 Suppose I am epistemically permitted to believe P, i.e., it would not be irrational for me to believe it. Am I thereby obliged to believe P, or are other options rationally available to me?2 Might I be equally rational in remaining agnostic about P, or even believing not-P? Or could even a slightly stronger or weaker degree of confidence be just as reasonable? (shrink)

find myself believing all sorts 0f things for which I d0 not possess evidence: that smoking cigarettes causes lung cancer, that my car keeps stalling because the carburetor needs LO be rebuilt, that mass media threaten democracy, that slums cause emotional disorders, that my irregular heart beat is premature ventricular contraction, that students} grades are not correlated with success in the ncmacadcmic world, that nuclear power plants are not safe (enough) . . . The list 0f things I believe, though (...) I have no evidence for the truth of them, is, if not infinite, virtually endless. And.. (shrink)

How should you take into account the opinions of an advisor? When you completely defer to the advisor's judgment, then you should treat the advisor as a guru. Roughly, that means you should believe what you expect she would believe, if supplied with your extra evidence. When the advisor is your own future self, the resulting principle amounts to a version of the Reflection Principle---a version amended to handle cases of information loss. When you count an advisor as an epistemic (...) peer, you should give her conclusions the same weight as your own. Denying that view---call it the ``equal weight view''---leads to absurdity: the absurdity that you could reasonably come to believe yourself to be an epistemic superior to an advisor simply by noting cases of disagreement with her, and taking it that she made most of the mistakes. Accepting the view seems to lead to another absurdity: that one should suspend judgment about everything that one's smart and well-informed friends disagree on, which means suspending judgment about almost everything interesting. But despite appearances, the equal weight view does not have this absurd consequence. Furthermore, the view can be generalized to handle cases involving not just epistemic peers, but also epistemic superiors and inferiors. (shrink)

How should one react when one has a belief, but knows that other people—who have roughly the same evidence as one has, and seem roughly as likely to react to it correctly—disagree? This paper argues that the disagreement of other competent inquirers often requires one to be much less confident in one’s opinions than one would otherwise be.

Th is paper investigates the epistemic powers of democratic institutions through an assessment of three epistemic models of democracy : the Condorcet Jury Th eorem, the Diversity Trumps Ability Th eorem, and Dewey's experimentalist model. Dewey's model is superior to the others in its ability to model the epistemic functions of three constitutive features of democracy : the epistemic diversity of participants, the interaction of voting with discussion, and feedback mechanisms such as periodic elections and protests. It views democracy as (...) an institution for pooling widely distributed information about problems and policies of public interest by engaging the participation of epistemically diverse knowers. Democratic norms of free discourse, dissent, feedback, and accountability function to ensure collective, experimentallybased learning from the diverse experiences of diff erent knowers. I illustrate these points with a case study of community forestry groups in South Asia, whose epistemic powers have been hobbled by their suppression of women's participation. (shrink)

Prejudiced beliefs may certainly seem like defective beliefs. But in what sense are they defective? Many will be false and harmful, but philosophers have further argued that prejudiced belief is defective also in the sense that it could only arise from distinctive kinds of epistemic irrationality: we could acquire or retain our prejudiced beliefs only by violating our epistemic responsibilities. It is also assumed that we are only morally responsible for the harms that prejudiced beliefs cause because, in forming these (...) beliefs in the first place, we are violating our epistemic responsibilities. In Prejudice, Endre Begby argues that these common convictions are misguided. His discussion shows in detail that there are many epistemically justified pathways to prejudiced belief, and that it is a mistake to lean on the concept of epistemic responsibility to articulate our ethical responsibilities. Doing so unreasonably burdens victims of prejudice with having to show that their victimizers were in a position to know better. Accordingly, Begby provides an account of moral responsibility for harm which does not depend on finding grounds for epistemic blame. This view is supported by a number of examples and case studies at individual, collective, and institutional levels of decision making. Additionally, Begby develops a systematic platform for non-ideal epistemology which would apply to a wide range of other social and epistemic phenomena of current concern, such as fake news, conspiracy theories, science scepticism, and more. (shrink)

Contemporary societies are often “polarized”, in the sense that sub-groups within these societies hold stably opposing beliefs, even when there is a fact of the matter. Extant models of polarization do not capture the idea that some beliefs are true and others false. Here we present a model, based on the network epistemology framework of Bala and Goyal, 784–811 1998), in which polarization emerges even though agents gather evidence about their beliefs, and true belief yields a pay-off advantage. As we (...) discuss, these results are especially relevant to polarization in scientific communities, for these reasons. The key mechanism that generates polarization involves treating evidence generated by other agents as uncertain when their beliefs are relatively different from one’s own. (shrink)

Belief polarization is said to occur when two people respond to the same evidence by updating their beliefs in opposite directions. This response is considered to be “irrational” because it involves contrary updating, a form of belief updating that appears to violate normatively optimal responding, as for example dictated by Bayes' theorem. In light of much evidence that people are capable of normatively optimal behavior, belief polarization presents a puzzling exception. We show that Bayesian networks, or Bayes nets, can simulate (...) rational belief updating. When fit to experimental data, Bayes nets can help identify the factors that contribute to polarization. We present a study into belief updating concerning the reality of climate change in response to information about the scientific consensus on anthropogenic global warming. The study used representative samples of Australian and U.S. participants. Among Australians, consensus information partially neutralized the influence of worldview, with free-market supporters showing a greater increase in acceptance of human-caused global warming relative to free-market opponents. In contrast, while consensus information overall had a positive effect on perceived consensus among U.S. participants, there was a reduction in perceived consensus and acceptance of human-caused global warming for strong supporters of unregulated free markets. Fitting a Bayes net model to the data indicated that under a Bayesian framework, free-market support is a significant driver of beliefs about climate change and trust in climate scientists. Further, active distrust of climate scientists among a small number of U.S. conservatives drives contrary updating in response to consensus information among this particular group. (shrink)

Why do people who disagree about one subject tend to disagree about other subjects as well? In this paper, we introduce a model to explore this phenomenon of ‘epistemic factionization’. Agents attempt to discover the truth about multiple propositions by testing the world and sharing evidence gathered. But agents tend to mistrust evidence shared by those who do not hold similar beliefs. This mistrust leads to the endogenous emergence of factions of agents with multiple, highly correlated, polarized beliefs.

Part of a symposium on *The Rationality of Perception* by Susanna Siegel (2017 Oxford University Press).

For epistemic subjects like us, updating our credences incurs epistemic costs. Expending our limited processing power and working memory to properly update our credences by some information can come at the cost of not responding to other available information. It is thus desirable to flesh out and compare alternative ways of taking information into account in light of cognitive shortcomings like our own. This paper is a preliminary attempt to do so. I argue that it is better, in a range (...) of circumstances and from the point of view of expected credal accuracy, for epistemic subjects like us not to update on available information that bears on propositions for which substantial evidence has been gathered than it is to update on information as it presents itself. In order to clarify the argument, and enable comparisons between information-response policies more generally, I develop a queue-theoretic model of learning for subjects with cognitive limitations. The model characterizes how policies for responding to information interact with a subject’s limitations to yield confidences. Finally, I discuss implications of the discussion for work on confidence, outright belief, and the relationship between those two states. The comparison of information-response policies helps to explain how some of the “biases” revealed by psychological research might be cognitively valuable, clarify views that take outright belief to be a kind of epistemic plan that resists reconsideration, and assuage certain “demandingness” worries for the hypothesis that we are credal reasoners. (shrink)

In this ‘age of information’, some worry that we get our news from online ‘echo chambers’, news feeds on our social media accounts that contain information from like‐minded sources. Filtering our information in this way seems prima facie problematic from an epistemic perspective. I vindicate this intuition by offering an explanation of what is wrong with online echo chambers that appeals to a particular kind of motivated reasoning, or bias due to one’s interests. This sort of bias affects, not which (...) evidence one is exposed to, but how one makes use of the evidence that one has, on the basis of one’s interests. I argue that consulting an online echo chamber often facilitates and amplifies this bias. I then draw some general conclusions about the potential downside of having ready access to so much information. (shrink)

In any domain of inductive reasoning, we must take care to distinguish between (i) which hypothesis my evidence supports, and (ii) the level of confidence I should have in the hypothesis, given my evidence. This distinction can help resolve the problem of peer demotion, a central point of contention in the epistemology of peer disagreement. It is true that disagreement does not provide evidence that I am right and you are wrong. But it need not, in order to lead to (...) peer demotion: instead, significant disagreement can erode my confidence in the initial peer assessment to a point where I can no longer rationally sustain the belief that we are equally reliable. One consequence of this solution is that the line dividing the Equal Weight view from its competitors emerges as an artifact of a mistakenly one-dimensional picture of the epistemic significance of peer disagreement. (shrink)

In this paper we present the results of a simulation study of credence developments in groups of communicating Bayesian agents, as they update their beliefs about a given proposition p. Based on the empirical literature, one would assume that these groups of rational agents would converge on a view over time, or at least that they would not polarize. This paper presents and discusses surprising evidence that this is not true. Our simulation study shows that these groups of Bayesian agents (...) show group polarization behavior under a broad range of circumstances. This is, we think, an unexpected result, that raises deeper questions about whether the kind of polarization in question is irrational. If one accepts Bayesian agency as the hallmark of epistemic rationality, then one should infer that the polarization we find is also rational. On the other hand, if we are inclined to think that there is something epistemically irrational about group polarization, then something must be off in the model employed in our simulation study. We discuss several possible interfering factors, including how epistemic trust is defined in the model. Ultimately, we propose that the notion of Bayesian agency is missing something in general, namely the ability to respond to higher-order evidence. (shrink)