Testimony is indispensable in the sciences. To deny the propriety of relying on it engenders an untenable scepticism. But this leaves open the issue of what exactly confers a scientist’s epistemic right to rely upon the word of her colleagues. Some authors have suggested a recipient of testimony enjoys an epistemic entitlement to trust the word of another as such, not requiring evidence of her trustworthiness, so long as there is not evidence of her untrustworthiness. I argue that, whether or (...) not such an on-no-evidence entitlement to believe what one is told exists, it shrinks to irrelevance in the explanation of the basis on which scientists take each other’s word in the scientific community. This is so, since a normally knowledgeable adult hearer is typically awash with relevant evidence, direct and circumstantial, for and against, concerning a teller’s trustworthiness, and this swamps any alleged entitlement to believe in the absence of such evidence. There need not be personal knowledge of the teller, since social role and topic provide evidence regarding trustworthiness. I also discuss the individuation of ‘testimony’ as an epistemic kind. I suggest that we should not attempt to define a category with sharp boundaries, but instead characterise a paradigm case—one person telling another something in face-to-face personal communication—and then notice other cases which both resemble and diverge from this in epistemically relevant features—lectures, media broadcasts, personal letters, personal diaries, etc.Author Keywords: Testimony; Justification; Knowledge; Individualism; Communication. (shrink)

I defend the acceptance principle for testimony (APT), that hearers are justified in accepting testimony unless they have positive evidence against its reliability, against Elizabeth Fricker's local reductionist view. Local reductionism, the doctrine that hearers need evidence that a particular piece of testimony is reliable if they are to be justified in believing it, must on pain of scepticism be complemented by a principle that grants default justification to some testimony; I argue that (APT) is the principle required. I consider (...) two alternative weaker principles as complements to local reductionism; one yields counter-intuitive results unless we accept (APT) as well, while the other is too weak to enable local reductionism to avoid scepticism. (shrink)

Radical empiricism is the view that experience is the only source of knowledge. Hence, radical empiricism denies the existence of a priori knowledge. Its most famous proponents are John Stuart Mill and W. V. Quine. Although both reject a priori knowledge, they offer different empiricist accounts of the knowledge alleged by their opponents to be a priori. My primary concern in this paper is not with the cogency of their positive accounts. My focus is their arguments against a priori knowledge. (...) My goal is to establish that although they offer very different arguments against the existence of a priori knowledge, each of their arguments suffers from a common defect. They both fail to appreciate the phenomenon of epistemic overdetermination and its role in the theory of knowledge. (shrink)