The term testimony in contemporary analytic philosophy is used as label for the spoken or written word, when this purports to pass on the speaker’s or writer’s knowledge, conveying factual information or other truth.

Testifying, or giving testimony, is a linguistic action, and testimony is its result, an audible speech act of telling or more extended discourse (perhaps recorded), or a legible written text. Interest in the topic has grown rapidly since the publication of C. A. J. Coady’s Testimony: A Philosophical Study (1992).

Testimony in this broad sense includes the central case of one person telling something to another in face-to-face communication, as well as a range of other cases, from public lectures, television and radio broadcasts, and newspapers to personal letters and e-mails, all kinds of purportedly factual books and other publications, and the information recorded in train timetables, birth registers, and official records of many kinds.

Philosophical Issues About Testimony

Philosophical Issues About Testimony - The big picture
Philosophical Issues About Testimony

The key interest of testimony is as a source for individual human knowledge, alongside perception, memory, inference, and intuition. Thus attaining a correct account of its epistemology is the core organizing issue for explanatory philosophical theorizing about testimony. This interlocks with several other issues.

First, there is no believing what one is told, without first understanding it—grasping both content and force of the speech act.And knowledge of what one was told surely rests on knowledge that one was told. Thus an account of testimony needs to be supplemented with an account of linguistic understanding—both its psychology and its epistemology.

Understanding in turn cannot be fully explained except as part of the large project of explaining linguistic meaning, the significance of words, which is grasped when a speech act is understood. Second, telling is just one of the many diverse activities that make up the human social institution of language.

C. A. J. Coady
C. A. J. Coady

Why and how it is epistemically justified to believe the purport of a linguistic act of telling turns on the nature of that act. Appreciation of the interpersonal relations involved in linguistic exchange, especially the commitments and norms involved in the making and reception of the speech act of assertion, must inform our account of testimony.

Third, an account of what makes belief acquired from testimony become knowledge will be persuasive only if it instances a convincing general conception of knowledge; and similarly for justified testimonial belief. Fourth, how is testimony best individuated as an epistemic kind?

It is clear that the following very broad category is not one about which any interesting generalizations may be made: whatever may, on occasion, be justifiedly inferred by an audience from observing someone assert that P. But exactly how narrow the kind is that we should discern as the core case—what we may call knowledge (or justified belief) from testimony—is debatable.

sarcasm and metaphor
sarcasm and metaphor

In general knowledge from testimony that P, there will be knowledge with that same content P; but knowledge of an intended message can also be acquired through sarcasm and metaphor, and despite minor linguistic infelicity by the speaker.

One may come to know that P, where one’s knowledge rests essentially on the fact that S told one that P, but where one’s reason for forming belief in what she said is not that one trusts her to know whereof she speaks, but that one has circumstantial evidence that her utterance, though not from knowledge, is nonetheless sure to be true.

A speaker, for instance one whose job it is to instruct, may convey empirically well-established facts that she for perverse reasons does not believe. Can others acquire knowledge from her instruction?

expression of knowledge
expression of knowledge

These and other problem cases render the precise individuation of our epistemic kind a subtle and debatable matter. Some argue that the core case is confined to when the testifier speaks from her own knowledge, and her audience trusts her to do so, accepting her word for what she tells on that basis.

This is argued to be the core case, because in it alone the audience accepts the teller’s linguistic act of assertion at face value as what it purports to be, an expression of knowledge.

She accepts the warrant to believe on her say-so offered by the teller. But others, considering cases such as those mentioned above, argue for a broader conception, on which it is not necessary that the testifier speak from knowledge in order for one to acquire knowledge from testimony.

The Ideal of Epistemic Autonomy Versus Modern Reliance on Knowledge at Secondhand, from Testimony

The Ideal of Epistemic Autonomy Versus Modern Reliance on Knowledge - Race queens
The Ideal of Epistemic Autonomy Versus Modern Reliance on Knowledge

An individualist strand in Western philosophy castigates belief derived from testimony as epistemically inferior. Plato (in the Theatetus) and Augustine (in De Magistro) despised its secondhand character and denied that knowledge, as opposed to mere belief, can ever be acquired from it.

Rene Descartes (in his Meditations on First Philosophy) insisted on building his knowledge afresh from individualist foundations, and John Locke (in his Essay on the Human Understanding) rejected “other men’s opinions floating in one’s brain” as never amounting to knowledge.

They were correct that belief derived from testimony is epistemically problematic and arguably inferior in two related respects, entailed by its being knowledge at secondhand.


First, one who forms belief that P on trust in another’s testimony does not herself possess the evidence for P, but instead a second-order warrant.Her own immediate basis for believing P is that she trusts her teller to knows whereof she speaks.

This entails that the teller, or some other person or group of people upstream of her in a chain of testimony, possesses nontestimonial evidence establishing the truth of P. The trusting recipient of testimony is committed to belief in the existence of this evidence, of which she is personally ignorant, and that her informants have evaluated it correctly.

Insistence that, for a first-class warrant amounting to knowledge one must possess the evidence for P oneself, would rule out all knowledge thus based on trust in the word of others—and hence, in others’ honesty and epistemic good judgment.

John Locke - Double O samething
John Locke

Second, such trust is epistemically risky.One who testifies that P in an act of assertion purports to speak from knowledge. But her own belief may be false: she may have failed to form belief in an epistemically responsible way, or may have been the subject of bad epistemic luck, and may have fallen into honest error. Or she may be insincere, intent on deception.

There are many entirely understandable and common human motives for this. Circumstances are many and frequent in which personal advantage may be gained by lying, and it can require altruism or courage to tell the truth in difficult circumstances.

These risks incurred in believing what others tell us mean that we should place our trust in the word of others discriminatingly and circumspectly. The epistemically responsible recipient of testimony will be aware of the need for both sincerity and competence about her topic in her source, and her response will be mediated by this.

Rene Descartes - imagine going picnic with the three of them
Rene Descartes

But the price of maintaining Descartes’s ideal of epistemic self-reliance would be infeasibly high, in the condition of extensive division of epistemic labor that characterizes our modern, highly socialized existence.

Topics that we know of, for the most part, only from testimony include: all of history, including our own early personal and family history; much of the geography and politics of the contemporary world; nearly all of knowledge in the various specialized domains of human inquiry—the natural and social sciences, humanities, and so forth.

In addition, we rely heavily in our daily lives on the fruits of advanced technology, from plumbing and motor mechanics to information technology and dentistry, about which most of us know little. Each one of us would be unimaginably epistemically and practically impoverished without knowledge learned from trust in the testimony of others.

The Tasks for a Positive Epistemology of Testimony

The Tasks for a Positive Epistemology of Testimony - A happy day
The Tasks for a Positive Epistemology of Testimony

A more constructive theoretical approach takes the primary task for epistemology to be the following: to explain precisely how and in what circumstances testimony can yield knowledge and justified belief. This task may be subdivided into micro and macro issues.

The central case of testimony occurs when one person tells something to another, thereby expressing her knowledge, and the other understands and believes her, taking her word for it. When all goes as it should, knowledge is thereby shared, and by recursion of this mechanism it may be diffused through a community of speakers of a shared language.

Our micro question is: How precisely is knowledge spread from teller to audience in this core process? What are the conditions for belief formed in what one is told to be justified, and knowledgeable?


The macro issues are: How pervasive is epistemic dependence on testimony, in the system of empirical belief of each of us? Can this epistemic dependence be eliminated, in principle or in practice? How much of one’s belief system would be left, after such pruning? We have already seen that a very great deal of what an individual believes, in our modern society, is learned initially from testimony.

This does not entail that these beliefs are still epistemically dependent on testimony, since the believer may later acquire other, independent evidence— for instance, when one sees for oneself a place of which one has previously only read. Support from coherence and inference to the best explanation may sustain a system of belief initially acquired from trust in testimony.

But testimony plays a key role in putting in place the framework—of land masses and seas, cities and nations, natural and social history, and so forth, in terms of which we theorize our experiences.


Thus the idea of eliminating dependence on testimony is problematic, and it is not clear that we have any beliefs that are entirely free of epistemic dependence on testimony—hence the unlivability of the supposed ideal of epistemic autonomy.

Hume (1777) thought that knowledge could be gained from testimony, but the warrant to believe it came only with empirical evidence of the reliability of testimony as a source.

Reid (1764), in contrast, argued that human nature includes two complementary dispositions, to truthfulness and trustfulness, and that this engenders a defeasible a priori warrant to trust others’ testimony.


Their two views instance what may be called the reductionist versus the anti-reductionist stance regarding our micro question: What is the basis of a hearer’s epistemic entitlement to trust what someone tells her? Coady argues against reductionism, in favor of the view that our knowledge from testimony can only be explained by positing an epistemic principle special to testimony.

There is an a priori, albeit defeasible, epistemic entitlement to trust any giver of testimony: One may presume true whatever one is told, so long as one is not aware of evidence that defeats one’s presupposition of the sincerity and competence of one’s informant. Coady advances several arguments for this view.

His first main argument is transcendental:We do gain justified belief, and knowledge, from testimony. But it is impossible noncircularly to establish that testimony is generally reliable; therefore (on pain of denying that testimony can yield knowledge) a hearer must be entitled in effect to presume this on no evidence.


His second argument invokes considerations about the interpretation of the language of a community, to argue that the supposition that all reports made in that community are false is incoherent.

He suggests that this fact underwrites an epistemic right to trust on no evidence, in the absence of defeaters. Burge (1993) gives another argument for antireductionism: Testimony is presumed to come from a rational source, and in the absence of counterevidence, such a source is presumed true.

Fricker (in Chakrabarti and Matilal 1994) argues against Coady’s transcendental argument, and presses the presumptive case for reductionism, from the epistemic riskiness of trusting others.


She argues that epistemic responsibility requires monitoring others for sincerity and competence, and believing what they tell only if there is empirical basis for trusting them.

Further questions include: What is the range of subject matters on which a person may properly defer to the word of another, so that testimony on it may properly be given and accepted?

For instance, can one properly accept, even defer to, another’s word on moral, or aesthetic matters? Extensive division of epistemic labor characterizes the sciences, and all academic disciplines in which there is a domain of specialized knowledge and inquiry.

research teams
research teams

There are many issues about the nature of trust and epistemic dependence in these specialized epistemic domains. In the sciences, many results depend on collaborative research from large numbers of individuals, members of collaborating research teams.

In history, the judicious evaluation of oral and written testimonial sources is methodologically crucial. The status of testimony in formal settings such as legal ones is another area of interest.

judicious evaluation - Office cuties
judicious evaluation
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