Testimony as a Source of Knowledge
Most of what each of us knows — history, geography, science, our own birth date — we learned from others, and the epistemology of testimony asks whether and how the say-so of other people can transmit knowledge and justify belief.
Definition
Testimony as a source of knowledge is the process by which a hearer comes to know or justifiedly believe something on the basis of a speaker's assertion, and the epistemology of testimony studies the conditions under which such transmission yields knowledge.
Scope
This topic covers testimony as an epistemic source: the central dispute between reductionists, who hold that testimonial justification reduces to the hearer's own perceptual, memorial, and inductive evidence about speakers' reliability, and anti-reductionists, who hold that testimony is a basic source carrying a default entitlement to believe. It includes the transmission of knowledge, the role of trust, and conditions for testimonial justification. It serves as a bridge to social epistemology, where testimony's social dimensions are pursued further.
Core questions
- Can testimony be a basic source of knowledge, or is it reducible to other sources?
- What justifies a hearer in accepting what a speaker tells them?
- Does the hearer need independent evidence of the speaker's reliability?
- How is knowledge transmitted, and can it be created, through testimony?
Key theories
- Reductionism
- Following a Humean line, the reductionist holds that a hearer is justified in believing testimony only on the basis of their own evidence — perception, memory, and induction — about the reliability of speakers, so testimony confers no new, irreducible warrant.
- Anti-reductionism
- Coady and others argue that testimony is a fundamental source on a par with perception, carrying a default entitlement to believe what one is told absent specific reasons for doubt, since no one could acquire the independent evidence reductionism demands.
History
Hume's discussion of testimony, especially regarding miracles, set the reductionist tone by demanding that testimony be weighed against experience, while Thomas Reid defended a basic principle of credulity. Coady's 1992 book revived the topic as a central concern of epistemology, and Fricker's careful formulation of the reductionism debate in 1995 framed the contemporary discussion, which now feeds directly into social epistemology.
Debates
- Reductionism versus anti-reductionism about testimonial justification
- Reductionists insist that accepting testimony requires the hearer's own evidence of the speaker's reliability, while anti-reductionists argue that such evidence is unavailable for most of what we learn and that testimony carries a default warrant; the dispute turns on whether trust can be epistemically basic.
Key figures
- David Hume
- Thomas Reid
- C. A. J. Coady
- Elizabeth Fricker
Related topics
Seminal works
- coady1992
- fricker1995
Frequently asked questions
- Why is testimony an epistemological problem at all?
- Because believing what others tell us seems to give us knowledge, yet we rarely check our informants' reliability for ourselves. The problem is to explain what, if anything, justifies this reliance: our own indirect evidence about speakers, or a basic entitlement to trust testimony.
- What is the difference between reductionism and anti-reductionism here?
- Reductionism holds that testimonial justification is built out of the hearer's own perceptual, memorial, and inductive evidence about whether speakers tend to be reliable. Anti-reductionism holds that testimony is a basic source carrying its own default warrant, so a hearer may justifiedly believe absent specific grounds for doubt.