Social knowledge, for the most part, is knowledge through testimony. This essay is an overview of the epistemology of testimony. The essay separates knowledge from justification, characterizes testimony as a source of belief, explains why testimony is a source of knowledge, canvasses arguments for anti-reductionism and for reductionism in the reductionism vs. anti-reductionism debate, addresses counterexamples to knowledge transmission, defends a safe basis account of testimonial knowledge, and turns to social norms as a partial explanation for the reliability of testimony.

[The version of this paper published by Oxford online in 2019 was not copy-edited and has some sense-obscuring typos. I have posted a corrected (but not the final published) version on this site. The version published in print in 2020 has these corrections.] Which is more fundamental, assertion or testimony? Should we understand assertion as basic, treating testimony as what you get when you add an interpersonal addressee? Or should we understand testimony as basic, treating mere assertion -- assertion without (...) testimony -- as what you get when you subtract that interpersonal relation? In this chapter, I’ll argue for the subtractive approach and for the more general thesis that its treatment of the interpersonal element in assertion makes understanding that interpersonal element the key to understanding how assertion expresses belief. My theory of belief-expression in assertion treats it as internalizing the transmission of belief in testimony. How we understand that internalizing move depends on how we conceptualize the interpersonal element in testimony. Since what I’ll call the Command Model does not give us the conceptual resources to make this move, we should adopt an alternative that I’ll call the Custodial Model, on which a testifier aims not to convince her addressee but to reason with him – to give him reasons to believe what she tells him grounded in her trustworthiness in thus attempting to influence him. The subtractive approach to assertion thus rests on a key distinction between the aims of reasoning and persuasion. (shrink)

The Assurance View, as advanced by Angus Ross and Richard Moran, makes the epistemology of testimony a matter of interpersonal commitments and entitlements. More specifically, I argue, their position is best understood as claiming that for someone’s belief to be testimonially justified is for some speaker to bear illocutionary responsibility for its truth. With this understanding in hand, I present a problem for the view that has so far escaped attention, a problem deriving from the wide freedom we have to (...) retract our assertions. Retraction dissolves the illocutionary responsibilities that were set up by preceding speech acts; but in some circumstances the epistemic significance of a retraction is effectively nil. We can therefore construct cases in which the responsibilities undertaken in testimony have been canceled, while the justification for belief based on it remains in place—and that shouldn’t be possible, if the Assurance View has things right. I present one such case and press its implications. (shrink)

Cognitivism about trust says that it requires belief that the trusted is trustworthy; non-cognitivism denies this. At stake is how to make sense of the strong but competing intuitions that trust is an attitude that is evaluable both morally and rationally. In proposing that one's respect for another's agency may ground one's trusting beliefs, second-personal accounts provide a way to endorse both intuitions. They focus attention on the way that, in normal situations, it is the person whom I trust. My (...) task is to develop an account of the latter insight without the controversial theoretical commitments of the former. I propose a functional account for why the second and third-personal ‘systems’ operate not just in parallel, but in tandem, in support of a cognitivist account of trust. (shrink)

This paper introduces and argues for the hypothesis that judgments of testimonial worth are central to our practice of normatively appraising speech. It is argued that judgments of testimonial worth are central both to the judgement that an agent has lied, and to the acceptance of testimony. The hypothesis that, in lying, an agent necessarily displays poor testimonial worth, is shown to resolve a new puzzle about lying, and the recalcitrant problem raised by the existence of bald faced lies, and (...) selfless assertions. It is then shown that the notion of testimonial worth allows us to capture the distinction between taking a speaker at their word, and treating them as a mere indicator of the truth in a way other theories fail to do. (shrink)

In this paper we argue that moral deference is prima facie obligatory in cases in which the testifier is a member of a marginalized social group that the receiver is not and testifies about their marginalized experience. We distinguish between two types of deference: epistemic deference, which refers to believing p in virtue of trusting the testifier, and actional deference, which involves acting appropriately in response to the testimony given. The prima facie duty we propose applies to both epistemic and (...) actional deference, though defeaters may quash either or both obligations. Even if one fails to epistemically defer to the marginalized testifier, we argue that they may still be ethically obligated to act in accordance with their testimony. (shrink)

According to the Interpersonal View of Testimony, testimonial justification is non-evidential in nature. I begin by arguing that the IVT has the following problem: If the IVT is true, then young children and people with autism cannot participate in testimonial exchanges; but young children and people with autism can participate in testimonial exchanges; thus, the IVT should be rejected on the grounds that it has over-cognized what it takes to give and receive testimony. Afterwards, I consider what I take to (...) be the two best motivations for the IVT and argue that they both fail. The overarching lesson, then, is that the IVT is unmotivated and false; we should think of testimonial justification as being evidential in nature. (shrink)

Philosophy and Phenomenological Research, EarlyView.

We gain information from collective, often institutional bodies all the time—from the publications of committees, news teams, or research groups, from web sites such as Wikipedia, and so on—but do these bodies ever function as genuine group testifiers as opposed to mere group sources of information? In putting the question this way I invoke a distinction made, if briefly, by Edward Craig, which I believe to be of deep significance in thinking about the distinctiveness of the speech act of testimony. (...) The distinction is that between somebody’s functioning as a ‘good informant’ and their functioning merely as a ‘source of information’. The difference between these has, as he remarks, a crucial ethical aspect: What I have in mind is the special flavour of situations in which human beings treat each other as subjects with a common purpose, rather than as objects from which services, in this case true belief, can be extracted. In this paper I shall try to bring out the distinctive nature of the role of good informant in a way that helps to clarify what is at stake in asking whether there can be group testimony in the sense of genuinely collective testimony—that is to say, where the group testifier is a collective and not merely a sum of individuals testifying in one or another form of aggregated chorus. (shrink)

According to the Assurance Theory of testimony, in telling an audience something, a speaker offers their assurance that what is told is true, which is something like their guarantee, or promise, of truth. However, speakers also tell lies and say things they do not have the authority to back up. So why does understanding tellings to be a form of assurance explain how tellings can provide a reason for belief? This paper argues that reasons come once it is recognised that (...) tellings are trusted. And the logic by means of which trust gives reason to believe is quite general; it applies equally to belief that is based on evidence rather than assurance. Outlining this logic requires the introduction of the idea of epistemic presumptions, whose truth plays the role of ensuring a connection between believer, justification and truth. (shrink)

According to many theories of testimony, acts of testimony confer certain epistemic rights upon recipients, e.g., the right for the recipient to complain or otherwise hold the testifier responsible should the content of that testimony turn out to be false, and the right to “pass the epistemic buck”, such that the recipient can redirect relevant challenges they may encounter back to the testifier. While these discussions do not explicitly exclude testimonial acts that occur online, they do not specifically address them, (...) either. Here, then, I will ask the following questions: do the differences between communicating in online and offline spaces affect our testimonial epistemic rights, and if so, how? While there is no singular “online space”, here I will focus on such spaces in which users communicate with one another, and in which communicated information can be vetted by other users (for example, social media). I argue that the characteristics of online testimony should make us think about testimonial epistemic rights differently, in two ways. First, whereas such rights have traditionally been conceived of as existing between the recipient and testifier, in many different types of online communication these rights exist between the recipient and a community. This is a result of the fact that online testimony is mediated, and in some cases partially determined by, a community of users. As such, testimonial epistemic rights in online spaces may be widely extended: while the original testifier still bears the brunt of responsibility for challenges, and is the primary buck-passee, all other members of the relevant community will also bear some such responsibilities. Second, the grounds of testimonial epistemic rights may differ in online spaces. Existing theories tend to ground such rights either in assurances provided by the testifier, or else norms that govern speech acts. I argue that testimony in online spaces should cause us to look to a third option, what I call norms of information sharing. The idea is that, given the highly social nature of online communication, a recipient acquires testimonial epistemic rights in virtue of having a reasonable expectation that information that is shared and vetted by the community meets certain standards. The grounds of online testimonial epistemic rights, then, is not primarily interpersonal or norms-based, but social. (shrink)

This thesis is set out as a collection of self-standing essays. Throughout these essays, I try to illuminate a number of controversies surrounding the way in which delusions are formed, and relatedly, their nature and epistemic standing. In Chapter 2, after an introductory chapter, I flesh out a new ‘endorsement’ approach to the Capgras delusion, the main idea being that the delusion is formed by endorsing the content of a metaphorical-perceptual state in which a loved one is represented metaphorically as (...) an imposter. In Chapter 3, I take issue with the idea, prevalent in the literature, that Bayesian accounts of inference in delusions are best characterised as versions of ‘explanationism’. Taking one such influential account as a test case, I argue that it is no more or less compatible with the endorsement alternative, which says delusions are acquired non-inferentially from experience. In Chapter 4, I examine a recent critique of predictive processing theories of delusions, according to which such theories suffer two limitations: they fail to explain why an agent believes something delusional as opposed to nothing at all or something else; they fail to explain how delusional hypotheses are generated in the first place. I suggest ways in which these concerns might be addressed. In Chapter 5, I consider how the Spinozan theory of belief fixation can improve the prospects of doxasticism about delusions. Doxasticism has been criticised on the grounds that delusions typically do not abide by rational standards which we expect beliefs to conform to. If belief fixation is Spinozan, I argue, these deviations from rationality are not just compatible with, but supportive of, their status as beliefs. In Chapter 6, I ask whether misidentification delusions formed via endorsement processes have any measure of perceptual justification. To give the best chance of getting a ‘yes’ answer, I address the question from the perspective of perceptual dogmatism, as this appears the best option if we are to grant at least defeasible justifiedness to MDs. I argue that, even so, MDs are completely unjustified. (shrink)

In this paper, I spell out a new challenge for epistemic internalism that emerges out of the current debate on testimonial justification. Based on recent developments within this debate, one might argue as follows: Epistemic internalism can’t account for the justification of our testimony-based beliefs, because (1) we should conceive of testimonial justification along anti-reductionist lines and (2) anti-reductionism is incompatible with epistemic internalism. In response to this challenge, I show that, despite initial appearances, epistemic internalism and anti-reductionism are compatible (...) after all. Therefore, being an anti-reductionist with regard to testimonial justification doesn’t force one to reject epistemic internalism. In order to argue for this result, I will make use of resources provided by speech act theory. (shrink)