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Books

Learning from Words: Testimony as a Source of Knowledge by Jennifer Lackey

David Fraser examines the validity of Jennifer Lackey’s testimony.

Until recently, the knowledge a hearer purports to gain from a speaker, or testimony, as it is formally called, has received scant and mostly negative attention among philosophers. This is surprising, since, in practice, the vast majority of what we philosophers claim as knowledge comes to us through testimony, via experts, institutions, and books. Sometimes we know little or nothing about the reliability or qualifications of these sources. So how should a hearer approach testimony: from a default position of trust, or from a skeptical position?

In her book, Learning from Words: Testimony as a Source of Knowledge, Jennifer Lackey, a professor of philosophy at Northwestern University in the USA, argues that discussion of the philosophy of testimony is polarized between credulity and skepticism in an unhelpful way. She seeks instead to present a balanced ‘dualist’ view where both speakers and hearers must contribute for knowledge to be gained. Furthermore, she argues that it is a speaker’s words that matter, not their beliefs.

Speakers & Hearers

Learning from Words begins with a brief survey of what testimony is. Lackey notes that testimony has traditionally been seen either in terms of an intentional act by a speaker to convey information, or in terms of an act of acceptance by a hearer. She proposes a blending of these two insights, and maintains that a speaker testifies to some given proposition through an act of communication if and only if that person intends to convey the proposition, and the communication is reasonably taken as conveying the proposition. The hearer must therefore correctly understand the communication, and must believe that the speaker intends to convey the proposition (although perhaps not to them).

The importance of this definition of testimony becomes clearer when you consider the ongoing debate between testimony reductionists and testimony non-reductionists. This debate can be traced back to the differing views of David Hume and Thomas Reid in the eighteenth century. The reductionists, traditionally associated with Hume, hold that to be justified in believing a speaker (and hence gaining knowledge through their testimony), a hearer must possess positive reasons to believe them which are not testimonially based. Testimony, these reductionists say, must therefore reduce to more ‘fundamental’ sources of knowledge, such as perception, memory, or reason, which themselves seem to need no further justification.

Non-reductionists, traditionally associated with Reid, hold that hearers need not possess additional positive reasons to believe a speaker. Testimony, they say, needs no further justification, and a speaker can provide knowledge to a hearer without additional positive reasons (so long as they have no reasons which would cause doubt about the testifier’s truthfulness).

On Lackey’s view both of these positions are mistaken. What has led to the polarization is that reductionists have focused entirely on the hearer in testimonial exchanges, while non-reductionists have focused only on the speaker. Lackey develops her definition of testimony as a sort of middle ground, so that testimonial exchanges require both a speaker whose testimony preserves truth, and a hearer who has appropriate reasons for believing it.

Statements & Reasons

A natural follow-up question concerns the nature of what is communicated. Do hearers form their belief on the basis of the speaker’s belief, or on the basis of the speaker’s words?

Adherents of the dominant view, ‘the belief view of testimony’, hold that sentences and statements are merely a means through which a speaker expresses private beliefs to others. On this view, testimony is about learning from the speaker’s beliefs. In contrast to this view, Lackey advocates what she calls the ‘statement view’ of testimony, which emphasizes that a hearer forms their belief as a result of understanding and accepting the words of a speaker.

The difference between communicating beliefs and communicating words is central to Lackey’s project. She attempts to flesh out the point with a series of crucial examples. Consider Creationist Teacher. Stella is a devoutly Christian fourth-grade teacher. Part of her faith is a belief in the truth of creationism and, thus, the falsity of evolution. Stella, however, recognizes that there is an overwhelming amount of evidence against the truth of creationism. She readily admits that she is basing her belief on her faith in an omnipotent creator. But, as a teacher, Stella takes it to be her duty to present the material that is best supported by evidence, and so after some research she asserts to her class “Modern-day Homo sapiens evolved from Homo erectus.” Though Stella neither knows, nor believes this proposition, her students form a corresponding true belief solely on the basis of her reliable testimony.

The question is, do Stella’s students know that modern-day Homo sapiens evolved from Homo erectus? According to Lackey the answer is ‘yes’. Creationist Teacher, she says, shows that although she’s an unreliable believer, Stella may still transmit knowledge, because her statements are all that is needed for her to be a reliable testifier: Stella’s belief does not convey knowledge, but Stella’s statements do. Through a similar example, Lackey also shows the converse – that a reliable believer may transmit knowledge even though she is an unreliable testifier. A testifier’s statements, then, are more important for conveying knowledge than their beliefs.

Reliability & Irrationality

I found Lackey’s book to be an informative read. The theory she advocates deserves recognition as an important contribution to the discourse on testimony. An attempt to move past emphasizing speakers at the expense of hearers, or hearers at the expense of speakers, is long overdue, and Lackey is clear and concise in drawing out the obligations placed on each.

However, there is at least one legitimate concern that can be raised against her project. Her statement view of testimony, as exemplified in Creationist Teacher, is problematic because it creates a division between being a reliable believer and being a reliable testifier. Stella believes the best-supported evidence is for evolution, but still believes that creationism is true. This, I think, is what motivates Lackey to think that Stella is an unreliable believer: Stella is not appropriately sensitive to evidence. But Stella is culpable of more than this; she is also being irrational. Rational people revise or re-evaluate their beliefs in the face of new evidence they cannot refute. Stella, instead, acknowledges the conflict between the best-supported evidence and her belief, and willfully ignores it. However, by intentionally ignoring strong evidence which counters her belief, Stella removes herself from meaningful debate. So Stella is not just unreliable, she is irrational too. This point is significant because when a hearer realizes that a testifier is purposely ignoring evidence, they have reason to doubt the reliability and so veracity of that testifier’s claims.

Lackey’s example is a little more complicated: since Stella’s student’s are not yet aware that she is being irrational, they have no reason to suspect that her testimony is unreliable. They may, in fact, have good reason to think that she is reliable. But, that Stella is able to hide her irrationality, or that her student’s do not recognize it, does not mean that Stella is reliable; it means that hearers are fallible. Consequently, Lackey’s statement that statements are more important than beliefs itself needs revision.

However, on the whole her theory moves the epistemology of testimony in new and compelling directions. For the philosophically sophisticated her Learning from Words will be an important text. For readers unfamiliar with previous work in this field, it will provide an introduction to the central problems and expose a variety of viewpoints. So despite its minor problems, Learning from Words, and the statement view of testimony it presents, are an important contribution to social epistemology, and will be helpful for anyone who has ever wondered about these issues.

David Fraser is a graduate student at Regent College in Vancouver, Canada. He is currently writing a thesis on the epistemology of testimony to complete his Master’s degree.

• Learning from Words: Testimony as a Source of Knowledge by Jennifer Lackey, Oxford University Press, 2010, 320 pages. ISBN 978-0199575619.