We citizens of the 21st century live in a world where division of epistemic labour rules. Most of what we know we learned from the spoken or written word of others, and we depend in endless practical ways on the technological fruits of the dispersed knowledge of others—of which we often know almost nothing—in virtually every moment of our lives. Interest has been growing in recent years amongst philosophers, in the issues in epistemology raised by this fact. One issue concerns (...) the depth and extent of our epistemic dependence on testimony, as we may label this broad epistemic source: Do we have any knowledge at all that is free of epistemic dependence on what we have learned from others? A related question is whether our entitlement to believe what we have learned from others can be explained without invoking any epistemic principles special to testimony. These questions concern, as it were, the macro-epistemology of testimony. In the present discussion I shall focus instead on the micro foundations. Testimony, in our broad sense, can occur through an extensive range of types of spoken and written means of purportedly factual communication, including telephone calls, e-mails and personal letters, lectures and radio broadcasts, newspapers, textbooks and encyclopaedias, personal diaries, and public records of all kinds. But the central paradigm—what started the whole communication thing off—is surely that of face-to-face spoken encounter, when one person tells something to another, thereby intending and hoping to share her knowledge with her audience. I begin by describing the speech act of telling, identifying what takes place in a felicitous act of telling. From the nature of the speech act of telling, we see precisely how it is that knowledge is, when all goes as it should, acquired from teller by trusting hearer, in such an act, and in acts of testimony more broadly. (shrink)

Many epistemologists agree that even very young children sometimes acquire knowledge through testimony. In this paper I address two challenges facing this view. The first (building on a point made in Lackey (2005)) is the defeater challenge, which is to square the hypothesis that very young children acquire testimonial knowledge with the fact that children (whose cognitive immaturity prevents them from having or appreciating reasons) cannot be said to satisfy the No-Defeaters condition on knowledge. The second is the extension challenge, (...) which is to give a motivated, extensionally-adequate account of the conditions on testimonial knowledge in early childhood. Neither challenge can be met merely by endorsing externalism about knowledge; but we can meet both by reconceiving the process that eventuates in the child’s consumption of testimony. My central thesis is that this process should be seen as implicating features of the child's social environment. The result is a novel anti-individualistic externalism about knowledge. (shrink)

Our folk epistemology says that if someone knows that P and tells you that P, then, given the absence of defeaters, if you believe what they tell you, you will come to know that P as well. A speaker's knowledge that P is then, for the most part, enough for a hearer to come to know that P. But there are counterexamples to this principle: testimonial knowledge does not always transfer from the speaker to the hearer. Why should that be (...) so? Because testimonial knowledge arises through the flow of information--from conclusive grounds--from the speaker through the speaker's assertion to the hearer's state of comprehension as of the speaker's assertion. A speaker's belief can be based on conclusive grounds, but the speaker's assertion may fail to provide conclusive grounds to the hearer. Then the hearer won't acquire knowledge, even from a knowledgeable speaker. Knowledge from testimony then works more like knowledge through perception. But wait, you say, that can't be so because testimony involves free will but perception does not. The essay ends with a broadly Hume inspired reply to this objection. (shrink)

Greco wants to understand the difference between knowledge generation and transmission. Doing so, he argues, will show that there are substantively different norms governing the two types of knowledge acquisition. I offer an alternative way of cashing out the difference between transmission and generation in non-normative terms.

How much linguistic understanding is required for testimonial knowledge acquisition? One answer is that, so long as we grasp the content expressed by the speaker, it does not matter if our understanding of it is poor. Call this the ‘Liberal View’ of testimony. This approach looks especially promising when combined with the thesis that we share a public language that makes it easy to grasp the right content. In this paper, I argue that this picture is epistemically problematic. Poor linguistic (...) understanding undermines our ability to recognise evidence and counterevidence for the testimonial content. Because of this, in many cases in which a hearer’s understanding is poor, her resultant testimonial belief will lack sufficient warrant to qualify as knowledge. Given that we often do not possess a sufficiently good understanding of the testimony we consume, I argue that we acquire far less knowledge through testimony than the Liberal View suggests. (shrink)

Hearsay or indirect testimony receives little discussion even today in epistemology, and yet it represents one of the cardinal modes for the transmission of knowledge and for human cognitive development. It suffices to think of school education whereby a student listens to teachers reporting knowledge acquired, often indirectly, from the most varied sources such as text books, newspapers, personal memory, television, etc… Or let us consider the importance of oral tradition in the social and cultural development of civilisations. Or even (...) let us call to mind the learning process of infants who, only thanks to the knowledge learned from others, succeed in learning the language. Finally, with the emerging digital technology, the information gleaned from third parties is influencing the creation of knowledge in a full gamut of fields, in a quasi-comprehensive manner. This leads us to claim that hearsay, despite the reductionist conceptual scheme to which epistemology has confined it in that indirect testimony, is in any case quintessential in the dissemination of knowledge. This work fully expounds upon the basic mechanism of indirect testimonial transmission and provides an epistemologically founded explanation of the cognitive possibilities of hearsay by investigating, in the light of the anti-reductionist paradigm, three mutually connected epistemic properties, namely trust, reputation and coherence, that are key in the epistemic justification of the truth acquired via an indirect testimony. (shrink)

Many of our beliefs are acquired online. Online epistemic environments are replete with fake news, fake science, fake photographs and videos, and fake people in the form of trolls and social bots. The purpose of this paper is to investigate the threat that such online fakes pose to the acquisition of knowledge. I argue that fakes can interfere with one or more of the truth, belief, and warrant conditions on knowledge. I devote most of my attention to the effects of (...) online fakes on satisfaction of the warrant condition, as these have received comparatively little attention. I consider three accounts of the conditions under which fakes compromise the warrant condition. I argue for the third of these accounts, according to which the propensity of fakes to exist in an environment threatens warrant acquisition in that environment. Finally, I consider some limitations on the epistemic threat of fakes and suggest some strategies by which this threat can be mitigated. (shrink)

This paper describes the ways in which trolls and bots impede the acquisition of knowledge online. I distinguish between three ways in which trolls and bots can impede knowledge acquisition, namely, by deceiving, by encouraging misplaced skepticism, and by interfering with the acquisition of warrant concerning persons and content encountered online. I argue that these threats are difficult to resist simultaneously. I argue, further, that the threat that trolls and bots pose to knowledge acquisition goes beyond the mere threat of (...) online misinformation, or the more familiar threat posed by liars offline. Trolls and bots are, in effect, fake persons. Consequently, trolls and bots can systemically interfere with knowledge acquisition by manipulating the signals whereby individuals acquire knowledge from one another online. I conclude with a brief discussion of some possible remedies for the problem of fake persons. (shrink)

Almost everyone believes that testimony can transmit knowledge from speaker to hearer. What some philosophers mean by this is ordinary and pedestrian-- they mean only that, in at least some cases, a speaker S knows that p, S testifies that p to a hearer H, and H comes to know that p as a result of believing S's testimony. There is disagreement about how this occurs, but that it does occur is sufficient for the transmission of knowledge in the intended (...) sense. On this understanding of transmission, the natural questions are these: (1) What conditions, in addition to speaker knowledge and speaker testimony, are sufficient for the hearer to gain testimonial knowledge?; and (2) Is speaker knowledge always necessary for testimonial knowledge? That is: Is all testimonial knowledge transmitted knowledge? (shrink)

Here are three (rough) theories of testimonial knowledge. (1) Speaker's knowledge: a hearer acquires the knowledge that P though testimony because of the speaker's knowledge that P--testimony "transfers" knowledge. This is the popular view, defended by Elizabeth Fricker and Paul Faulkner, among others. (2) Speaker's assertion: a hearer acquires the knowledge that P through testimony because the speaker's assertion that P is reliable that P in the right way (safe or sensitive). That's Jennifer Lackey's view. (3) Speaker's comprehension state: a (...) hearer acquired the knowledge that P through comprehending as of a speaker's assertion that P where the comprehension state is reliable in the right way (safe). That's my view. Lackey would reject such a view for it allows cases of testimonial knowledge that P from a speaker who did not assert that P. But Faulkner might reject Lackey's view on the grounds that it allows cases of testimonial knowledge that P from a speaker who did not know that P. Lackey replies that her account is better unified. But for the same reason, my account is even better unified. This paper runs through a series of cases and shows that my account--the Unified Account--is superior to the others. (shrink)

This paper states three counterexamples to the claim that testimony cannot generate knowledge, that a hearer can only acquire testimonial knowledge from a speaker who knows: a twins case, the fossil case, and an inversion case. The paper provides an explanation for why testimony can generate knowledge. Testimonial knowledge involves the flow of information from a speaker to a hearer through the linguistic channel.

Many people agree that a proper epistemological treatment of testimonial knowledge will regard testimonial warrant—the total truth-conducive support enjoyed by a belief grounded on a piece of testimony —as socially diffuse, in the sense that it is not something that supervenes on the proper functionality of the hearer’s cognitive resources together with the reasons she has for accepting the testimony. After arguing for such a view, I go on to identify a challenge many people think flows from an acknowledgment of (...) the social diffusion of warrant. In particular, such an acknowledgment appears to preclude a happy account of the rationality of testimony-based belief. After identifying the nature of this challenge and the various positions that one can take on it, I develop a response according to which rationality itself (like warrant) is socially diffuse. (shrink)

Many epistemologists agree that even very young children sometimes acquire knowledge through testimony. In this paper I address two challenges facing this view. The first (building on a point made in Lackey (2005)) is the defeater challenge, which is to square the hypothesis that very young children acquire testimonial knowledge with the fact that children (whose cognitive immaturity prevents them from having or appreciating reasons) cannot be said to satisfy the No‐Defeaters condition on knowledge. The second is the extension challenge, (...) which is to give a motivated, extensionally‐adequate account of the conditions on testimonial knowledge in early childhood. Neither challenge can be met merely by endorsing externalism about knowledge; but we can meet both by reconceiving the process that eventuates in the child’s consumption of testimony. My central thesis is that this process should be seen as implicating features of the child’s social environment. The result is a novel anti‐individualistic externalism about knowledge. (shrink)

We citizens of the 21st century live in a world where division of epistemic labour rules. Most of what we know we learned from the spoken or written word of others, and we depend in endless practical ways on the technological fruits of the dispersed knowledge of others—of which we often know almost nothing—in virtually every moment of our lives. Interest has been growing in recent years amongst philosophers, in the issues in epistemology raised by this fact. One issue concerns (...) the depth and extent of our epistemic dependence on testimony, as we may label this broad epistemic source: Do we have any knowledge at all that is free of epistemic dependence on what we have learned from others? A related question is whether our entitlement to believe what we have learned from others can be explained without invoking any epistemic principles special to testimony. These questions concern, as it were, the macro-epistemology of testimony. In the present discussion I shall focus instead on the micro foundations. Testimony, in our broad sense, can occur through an extensive range of types of spoken and written means of purportedly factual communication, including telephone calls, e-mails and personal letters, lectures and radio broadcasts, newspapers, textbooks and encyclopaedias, personal diaries, and public records of all kinds. But the central paradigm—what started the whole communication thing off—is surely that of face-to-face spoken encounter, when one person tells something to another, thereby intending and hoping to share her knowledge with her audience. I begin by describing the speech act of telling, identifying what takes place in a felicitous act of telling. From the nature of the speech act of telling, we see precisely how it is that knowledge is, when all goes as it should, acquired from teller by trusting hearer, in such an act, and in acts of testimony more broadly. (shrink)

In this paper, I give an answer to the central epistemic question regarding the normative requirements for beliefs based on testimony. My suggestion here is that our best strategy for coming up with the conditions for justification is to look at cases where the adoption of the belief matters to the person considering it. This leads me to develop, in Part One of the paper, an interest-relative theory of justification, according to which our justification for a proposition p depends on (...) our evidence in favour of p in proportion to our interest in p, as signalled by the epistemic risk we take in believing that p is true. In Part Two, I argue that this theory shows that the reductivist view offers a better normative account for the epistemic status of beliefs based on testimony than the credulist one, but it is inaptly named; the view I develop here is better conceived of as The Dependence Account. (shrink)

We must allow that knowledge can be transmitted. But to allow this is to allow that an individual can know a proposition despite lacking any evidence for it and reaching belief by an unreliable means. So some explanation is required as to how knowledge rather than belief is transmitted. This paper considers two non-individualistic explanations: one in terms of knowledge existing autonomously, the other in terms of it existing as a property of communities. And it attempts to decide what is (...) at issue between these explanations. (shrink)

In this paper, I criticise one main strategy for supporting anti-intellectualism, the view that whether a subject knows may depend on the stakes. This strategy appeals to difficulties with developing contextualist and pragmatic treatments of the shiftiness of our talk about knowledge to motivate anti-intellectualism. I criticise this strategy by drawing an analogy between debates about causation and knowledge. In each case, talk about a phenomenon is shifty and contextualist and pragmatic explanations of the shifty talk face the same objections. (...) However, in the case of causation it would be implausible to argue that difficulties with the relevant contextualist and pragmatic accounts motivate a revisionary metaphysics of causation. I conclude that the defender of anti-intellectualism needs to employ a different strategy to defend her view. (shrink)

It has recently been argued that public linguistic norms are implicated in the epistemology of testimony by way of underwriting the reliability of language comprehension. This paper argues that linguistic normativity, as such, makes no explanatory contribution to the epistemology of testimony, but instead emerges naturally out of a collective effort to maintain language as a reliable medium for the dissemination of knowledge. Consequently, the epistemologies of testimony and language comprehension are deeply intertwined from the start, and there is no (...) room for grounding the one in terms of the other. (shrink)