# Philosophy of testimony
## Introduction

The philosophy of testimony is a subfield of epistemology that examines the nature, scope, and justification of beliefs acquired through the testimony of others. Testimony, in this context, refers to the act of conveying information from one person to another, typically through speech or writing. The central questions in the philosophy of testimony include how we come to know things through the words of others, the conditions under which testimony is reliable, and the ethical implications of believing or disbelieving others.
The Role of Epistemic Authority
According to Christoph Jäger in his chapter on Epistemic Authority (2025), testimony is a fundamental source of knowledge, as it allows individuals to rely on the expertise and authority of others. Jäger argues that epistemic authority is often ascribed to individuals who possess superior knowledge or understanding in a particular domain. For example, when deciding whether to get a vaccine, one might consult a trained medical doctor or an internet personality spreading conspiracy theories. The doctor, as an epistemic authority, has expertise based on years of research and clinical practice, making their testimony more reliable. However, some individuals may still treat the conspiracy theorist as an authority due to personal biases or distrust in institutions. This highlights the challenge of distinguishing genuine epistemic authorities from unreliable sources. Jäger also warns about the risk of epistemic dependence, where individuals may overly rely on authorities without critically evaluating their claims.
Interpersonal Aspects of Testimony
In a similar vein, Berislav Marušić (2024), explores the concept of interpersonal reasoning in his article Interpersonal Reasoning: A Philosophical Psychology of Testimonial Trust. Marušić argues that believing someone involves a distinctive kind of reasoning that is fundamentally interpersonal. He draws an analogy between practical reasoning and interpersonal reasoning, suggesting that just as practical reasoning involves deciding to act based on what one sees as good, interpersonal reasoning involves trusting someone for the truth based on their testimony. Marušić emphasizes that this form of reasoning is not merely about evaluating evidence but about recognizing the speaker as a knower and engaging in a shared epistemic practice. This recognition, according to Marušić, is what distinguishes believing someone from merely treating their testimony as evidence.
Richard Moran (2020), in The Exchange of Words, further develops the idea of testimony as a social act that involves mutual recognition between the speaker and the hearer. Moran argues that when a speaker tells someone something, they are offering an assurance of the truth, and the hearer's belief in the speaker is based on this assurance rather than on inductive evidence. Moran argues that testimony works because speakers offer assurances, and hearers trust them rather than just evaluating evidence. He suggests that the act of telling is completed through mutual recognition, where the speaker and the hearer align in their understanding of the reason for belief.
Testimonial Injustice and Ethical Concerns
Miranda Fricker (2007), in her seminal work Epistemic Injustice, introduces the concept of testimonial injustice, which occurs when a speaker is not believed due to prejudice or bias. Fricker argues that testimonial injustice undermines the speaker's capacity as a knower and can lead to significant ethical and epistemic harms. A well-documented example of this is the historical dismissal of women’s pain in medical settings. Studies have shown that women’s reports of pain are often taken less seriously than men’s, leading to misdiagnoses or delayed treatments. For instance, heart attack symptoms in women frequently go unrecognized because doctors have historically relied on male-centered diagnostic models. This illustrates how prejudice can distort credibility judgments and result in real-world harm. This likewise emphasizes that the act of believing someone is not just an epistemic matter but also an ethical one, as it involves recognizing the speaker's credibility and treating them with respect. Fricker's work highlights the importance of trust in testimonial exchanges and the need to address systemic biases that can distort our judgments of others' credibility.
philosophy of testimony (also, epistemology of testimony) considers the nature of language and knowledge's confluence, which occurs when beliefs are transferred between speakers and hearers through testimony. Testimony constitutes words, gestures, or utterances that convey beliefs. This definition may be distinguished from the legal notion of testimony in that the speaker does not have to make a declaration of the truth of the facts.
The role of testimony in acquiring belief and knowledge has been a relatively neglected philosophical issue. CAJ (Tony) Coady believes that this is because traditional epistemology has had a distinctly individualist flavour.
However, it seems that many of the beliefs that we hold have been gained through accepting testimony. For example, one may only know that Kent is a county of England or that David Beckham earns $30 million per year because one has learned these things from other people. A more striking example is the belief about one's own birthdate. If you know your birthdate, the evidence for your belief was almost certainly received through testimony.
One of the problems with acquiring knowledge through testimony is that it does not seem to live up to the standards of knowledge (see justification of knowledge in philosophy ). As Owens notes, it does not seem to live up to the Enlightenment ideal of rationality captured in the motto of the Royal Society – ‘Nullius in verba (Into the word of no one)’. The Royal Society interprets this as "take nobody's word for it." Crudely put, the question is: 'How can testimony give us knowledge when we have no reasons of our own?'
Reductionism and Anti-Reductionism
A key debate in this field is whether testimony requires independent support to be a source of knowledge. Reductionists argue that testimonial knowledge is only justified when backed by other evidence, much like perception or inference. This view, associated with David Hume, treats testimony as something that must be verified before it can be trusted. Anti-reductionists, on the other hand, maintain that testimony is a fundamental source of knowledge in its own right, requiring no external confirmation. Thomas Reid, a major proponent of this view, argues that trusting others is a natural and necessary part of human cognition. This debate informs many discussions on epistemic authority, testimonial trust, and the social dynamics of knowledge transmission. suggests that there are two approaches to this problem:
* Reductivism, which seeks to ‘reduce’ or re-describe our behaviour such that it is not at odds with the traditional view of knowledge
and
* Anti-reductivism, which seeks to fit our behaviour in with a different concept of knowledge. For example, we may compare it to an account of how perception gives us knowledge or how memory gives us knowledge directly.
Hume is one of the few early philosophers to offer anything like a sustained account of testimony, this can be found in his ‘An Enquiry Concerning Human Understanding’ in the section on miracles. The basic idea is that our justification for believing what people tell us comes from our experience of the ‘...constant and regular conjunction’ between the state of affairs as people describe it and the actual state of affairs (i.e. our observation that they match). On Coady's schema he is a reductivist.
Coady offers an anti-reductivist account of testimony. He claims that testimony is like perception, we don't have to have reasons for believing it, only an absence of reasons not to believe it. On Coady's account we are justified in being credulous. Proponents of anti-reductivism in the history of philosophy include Augustine of Hippo and Thomas Reid.
Perhaps also significant is that Bertrand Russell argued that knowledge by acquaintance played an important part in epistemology.