Taking seriously the social dimensions of knowledge puts pressure on the assumption that epistemic agents can usefully be thought of as autonomous, interchangeable individuals, capable, insofar as they are rational and objective, of transcending the specificities of personal history, experience, and context. If this idealization is abandoned as the point of departure for epistemic inquiry, then differences among situated knowers come sharply into focus. These include differences in cognitive capacity, experience, and expertise; in access to information and the heuristics that make it intelligible; and in motivating interests and orienting standpoint. Dissent takes on rather different significance, as a potentially productive feature of epistemic life rather than evidence of a failure of aperspectivality or an indication of error. The central questions are, then, what forms of diversity are epistemically consequential, and how can they best be deployed to ensure that the beliefs we warrant as knowledge are as well grounded and truth-tracking as possible.

Diversity of opinion both presents problems and affords opportunities. Differences of opinion can stand in the way of reaching an agreement within a group on what decisions to take. But at the same time, the fact that the differences in question could derive from access to different information or from the exercise of different judgemental skills means that they present individuals with the opportunity to improve their own opinions. This paper explores the implications for solutions to the former (aggregation) problem of supposing that individuals exploit these opportunities. In particular, it argues that rational individual revision of opinion implies that aggregation problems are unstable in a certain sense and that solving them by exploiting the information embedded in individual opinion has profound implications for the conditions that we should impose on aggregation procedures.

This paper investigates the epistemic powers of democratic institutions through an assessment of three epistemic models of democracy: the Condorcet Jury Theorem, the Diversity Trumps Ability Theorem, 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, experimentally-based learning from the diverse experiences of different 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.

Epistemic diversity is widely approved of by social epistemologists. This paper asks, more specifically, how much epistemic diversity, and what kinds of epistemic diversity are normatively appropriate? Both laissez-faire and highly directive approaches to epistemic diversity are rejected in favor of the claim that diversity is a blunt epistemic tool. There are typically a number of different options for adequate diversification. The paper focuses on scientific domains, with particular attention to recent theories of smell.

The standard image of how consensus can be achieved is by pooling evidence and reducing if not eliminating disagreements. But rather than just pooling substantive evidence on a certain question, why not also take into account the formal, testimonial evidence provided by the fact that a majority of the group adopt a particular answer? Shouldn't we be reinforced by the discovery that we are on that majority side, and undermined by the discovery that we are not? Shouldn't this be so, in particular, when Condorcet's jury theorem applies? It turns out not. There are serious problems attending any strategy of majoritarian deference.

Recent discussions of rational deliberation in science present us with two extremes: unbounded optimism and sober pessimism. Helen Longino (1990) sees rational deliberation as the foundation of scientific objectivity. Miriam Solomon (1991) thinks it is overrated. Indeed, she has recently argued (2006) that group deliberation is detrimental to empirical success because it often involves groupthink and the suppression of dissent. But we need not embrace either extreme. To determine the value of rational deliberation we need to look more closely at the practice and practitioners of science. I offer a closer look here by exploring the joint agency of small research teams. Although there are factors that contribute to the suppression of dissent in group contexts, a closer look at the literature on group dynamics suggests that there are ways to mitigate the effects of groupthink. Thus, there is reason to be cautiously optimistic about the value of rational deliberation within certain scientific contexts.

We know that we can learn much from the reports of multiple competent, independent, unbiased observers. There are also things we can learn from the reports of competent but biased observers. Specifically, when reports go against the grain of an agent’s known biases, we can be relatively confident in the veracity of those reports. Triangulating on the truth via that mechanism requires a multiplicity of observers with distinct biases, each of whose reports might be one-way decisive in that fashion. It also presupposes that all observers share the same fundamental epistemic standards.

It is often assumed that democracies can make good use of the epistemic benefits of diversity among their citizenry, but difficult to show why this is the case. In a deliberative democracy, epistemically relevant diversity has three aspects: the diversity of opinions, values, and perspectives. Deliberative democrats generally argue for an epistemic form of Rawls' difference principle: that good deliberative practice ought to maximize deliberative inputs, whatever they are, so as to benefit all deliberators, including the least effective. The proper maximandum of such a principle is not the pool of reasons, but rather the availability of perspectives. This sort of diversity makes robustness across different perspectives the proper epistemic aim of deliberative processes. Robustness also offers a measure of success for those democratic practices of inquiry based on the deliberation of all citizens.

There are many reasons why scientific experts may mask disagreement and endorse a position publicly as “jointly accepted.” In this paper I consider the inner workings of a group of scientists charged with deciding not only a technically difficult issue, but also a matter of social and political importance: the maximum acceptable dose of radiation. I focus on how, in this real world situation, concerns with credibility, authority, and expertise shaped the process by which this group negotiated the competing virtues of reaching consensus versus reporting accurately the nature and degree of disagreement among them.

For multiple reasons, deliberating groups often converge on falsehood rather than truth. Individual errors may be amplified rather than cured. Group members may fall victim to a bad cascade, either informational or reputational. Deliberators may emphasize shared information at the expense of uniquely held information. Finally, group polarization may lead even rational people to unjustified extremism. By contrast, prediction markets often produce accurate results, because they create strong incentives for revelation of privately held knowledge and succeed in aggregating widely dispersed information. The success of prediction markets offers a set of lessons for increasing the likelihood that groups can obtain the information that their members have.

Alvin Goldman has criticized the idea that, when evaluating the opinions of experts who disagree, a novice should “go by the numbers”. Although Goldman is right that this is often a bad idea, his argument involves an appeal to a principle, which I call the non-independence principle, which is not in general true. Goldman's formal argument for this principle depends on an illegitimate assumption, and the examples he uses to make it seem intuitively plausible are not convincing. The failure of this principle has significant implications, not only for the issue Goldman is directly addressing, but also for the epistemology of rumors, and for our understanding of the value of epistemic independence. I conclude by using the economics literature on information cascades to highlight an important truth which Goldman's principle gestures toward, and by mounting a qualified defense of the practice of going by the numbers.

Classical Athens provides a historical case study of effective joint action by a democratic community, at scale, over time, and across a socially and epistemically diverse population. Athens was concerned both with aggregating diverse knowledge for decision-making and with building common knowledge for coordinated joint action. A preserved prosecution speech delivered in an Athenian treason trial reveals how common knowledge was generated by democratic institutions and employed in legal arguments. Common knowledge facilitated effective coordination among citizens through productive alignment cascades. Yet Athenian lawcourt procedures rendered cascading difficult, pointing to an institutionalized awareness that coordination among jurors might violate fairness as equality before the law; such violations threatened democratic values and the equilibrium between elite and non-elite citizens. Common knowledge was promoted by repeated public rituals, public monuments, and public architecture that allowed for the interpresence of large numbers of deliberative and intervisible citizens.

Epistemologists generally think that genuine warrant that is available to anyone must be available to everyone who is exposed to the relevant causal inputs and is able and willing to properly exercise her rationality. The motivating idea behind this requirement is roughly that an objective view is one that is not bound to a particular perspective. In this paper I ask whether the aperspectivality of our warrants is a precondition for securing the objectivity of our claims. I draw upon a Sellarsian account of perception in order to argue that it is not; rather, inquirers can have contingent properties and perspectives that give them access to forms of rational warrant and objective knowledge that others do not have. The universal accessibility of reasons, on my account, is not a precondition for the legitimacy of any actual warrant, but rather a regulative ideal governing inquiry and communication.

Much liberal theorizing of the past twenty years has been built around a conception of neutrality and an accompanying virtue of reasonableness according to which citizens ought to be able to view public policy debates from a perspective detached from their comprehensive conceptions of the good. The view of “justificatory neutrality” that emerges from this view is discussed and rejected as embodying controversial views about the relationship of individuals to their conceptions of the good. It is shown to be based upon a “protestant” assumption according to which conceptions of the good can be cashed out in terms of propositional beliefs. An alternative conception of reasonableness, grounded in the stable disposition of individuals to prefer social peace over conflict is described. It is argued that it better satisfies the neutralist requirement than do theories of justificatory neutrality.

Our understanding of social experiences is central to our social understanding more generally. But this sphere of epistemic practice can be structurally prejudiced by unequal relations of power, so that some groups suffer a distinctive kind of epistemic injustice—hermeneutical injustice. I aim to achieve a clear conception of this epistemicethical phenomenon, so that we have a workable definition and a proper understanding of the wrong that it inflicts.

Epistemic trustworthiness is defined as a complex character state that supervenes on a relation between first- and second-order beliefs, including beliefs about others as epistemic agents. In contexts shaped by unjust power relations, its second-order components create a mutually supporting link between a deficiency in epistemic character and unjust epistemic exclusion on the basis of group membership. In this way, a deficiency in the virtue of epistemic trustworthiness plays into social/epistemic interactions that perpetuate social injustice. Overcoming that deficiency and, along with it, normalized practices of epistemic exclusion, requires developing a self-critical perspective on the partial, socially-located character of one's perspective and the consequent epistemic value of inclusiveness.

Although John Stuart Mill places considerable emphasis on three information signalling devices – debate, votes and prices – he remains curiously sceptical about the prospects of institutional or social epistemology. In this paper, I explore Mill's modest scepticism about institutional epistemology and compare and contrast that with the attitudes of liberal theorists such as F. A. Hayek and John Dewey who are much more enthusiastic about the prospects of social epistemology as part of their defences of liberalism. The paper examines the extent to which Hayek and Dewey ignore concerns originally raised by Mill. I conclude that Mill's modest scepticism is reflected in the epistemological abstinence of contemporary liberal philosophers such as John Rawls, and that his elevation of philosophy over democracy remains a challenge to contemporary defenders of the political value of social or institutional epistemology.

Sandra Harding's feminist standpoint epistemology makes two claims. The thesis of epistemic privilege claims that unprivileged social positions are likely to generate perspectives that are “less partial and less distorted” than perspectives generated by other social positions. The situated knowledge thesis claims that all scientific knowledge is socially situated. The bias paradox is the tension between these two claims. Whereas the thesis of epistemic privilege relies on the assumption that a standard of impartiality enables one to judge some perspectives as better than others, the situated knowledge thesis seems to undermine this assumption by suggesting that all knowledge is partial. I argue that a contextualist theory of epistemic justification provides a solution to the bias paradox. Moreover, contextualism enables me to give empirical content to the thesis of epistemic privilege, thereby making it into a testable hypothesis.