Nullius in verba: Recent studies in the epistemology of testimony

Studies in History and Philosophy of Science 43 (2012) 412–419

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Essay Review

Nullius in verba: Recent studies in the epistemology of testimony Aviezer Tucker University of Texas, Flawn Academic Center, 2 West Mall C2400, TX, Austin 78712, United States

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Jennifer Lackey, Learning from words: Testimony as a source of knowledge. (2008). Oxford: Oxford University Press. Sanford C. Goldberg, Relying on others: An essay in epistemology. (2010). Oxford: Oxford University Press. The epistemology of testimony may be the most innovative and exciting sub-field of current epistemology. For most of the history of epistemology, the epistemologies of empirical and a-priori knowledge had been privileged over the other three sources of knowledge, testimonies, introspection, and memory. This neglect has recently begun to be remedied. Lackey and Goldberg’s books on the epistemology of testimony follow in the wake of Coady’s (1992) groundbreaking first book and the many articles that ensued. Since these three sub-fields of epistemology had suffered severe neglect, they are philosophical ‘‘green pastures’’ that offer great opportunities for growth and innovation. Lackey and Goldberg’s books discuss the main problems of the epistemology of testimony: What is testimony? How do we gain knowledge from testimonies? What justifies or warrants the knowledge that we gain from testimony? Is testimonial knowledge sui generis or is it reducible in part or whole to other sources of knowledge? Lackey’s Learning from Words is not about learning, but about knowing from words. I guess that Learning had to replace Knowing because the title Knowing from Words had already been taken by an excellent anthology about the epistemology of testimony and a succinct but decisive opening article with that title in the anthology by Strawson (1994). Goldberg reports that the original title of his book was Socializing Reliability. Goldberg divulges that the present title is his response to his son’s recommendation not to advertise just how boring the book may be. Since there may be scarcity of ideas for titles of books in the epistemology of testimony, let me make a few suggestions: Nullius in verba is already taken by the Royal Society. But a free associated translation to English may be as catchy as Don’t Take my/their/our Word. A non-reductionist book can be entitled I Told You So. Lackey attempts to develop a synthetic approach that combines reductionist and non-reductionist

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elements, so an appropriate title could have been something like I told you so, but don’t take my word for it. Lackey argues against the transmission view of testimony that considers testimony to exclusively transmit rather than generate knowledge. Knowledge, on this view, is generated by one of its other sources, most notably by the senses and inference. Testimonies are analogous to coins that, once minted, can only be passed from hand to hand or get lost. Lackey argues convincingly that testimonies can generate knowledge and are a legitimate sui generis source of knowledge. Much of Learning from Words is devoted to rebutting the transmission view of testimony and to working out a carefully detailed alternative generative view. In a supplement, Lackey develops an analogous argument about the epistemology of memory. She argues against the preservation view of memory which claims that memory at most can preserve knowledge generated by other sources. I agree with Lackey’s criticisms of the transmission view and with her generative alternative. I find the thought-experimental method she uses to reach these conclusions less persuasive. Her choice of methodology is unfortunate because there is a surer and easier method to reach similar conclusions. Lackey tests epistemic concepts and hypotheses against thought experiments that involve testimonies, beliefs and knowledge. The results of these thought experiments should generate universal intuitions that should refute some philosophical hypotheses or demonstrate the limits of some epistemic concepts or intuitions and show how their alternatives survive the same thought experiments. When thought experiments are simple and mundane, assuming clearly familiar even if tacitly understated background conditions, they can be useful for epistemology. Under ordinary and simple conditions, people with similar backgrounds may share similar or identical intuitions and interpretations of the thought experiments and their philosophic implications. However, outlandish thought experiments often do not and cannot explicate clearly which background or ceteris paribus conditions they assume. The more complex and outlandish the thought experiments, the more underdetermined are their conclusions because they give rise to conflicting intuitions that are

A. Tucker / Studies in History and Philosophy of Science 43 (2012) 412–419

partly based on different background assumptions. (Peijnenburg & Atkinson, 2003; Wilkes, 1988, pp. 6–21, 43–48). As Faulkner (2009) argued, the results of Lackey’s thought experiments as counter examples to received views are not entirely plausible and are open to reinterpretation. Faulkner demonstrates this critique convincingly, arguing either that the thought experiments do not involve testimonial knowledge or that the source of the testimony is actually not the last person to say the words that cause the belief in the hearer. Some of the thought experiments Lackey presents are complex, outlandish and consequently indecisive. This effect is exacerbated by the Alvin Goldman inspired nature of some of the experiments, considering cases of belief that do not entail knowledge. As Gendler-Szabó and Hawthorne (2010) showed, such thought experiments generate particularly unstable intuitions. In some other cases, I would argue, Lackey draws conclusions from thought experiments that are inconsistent with more reliable empirical results. Lackey expresses similar criticisms of outlandish thought experiments. She emphasizes that the problems of the epistemology of testimony are in this world rather than in alternative possible worlds. ‘‘Brain-in-the-vat,’’ ‘‘Cartesian demon,’’ sorts of possible worlds are ‘‘distant from the actual world.’’ Even a world ‘‘where my perceptual faculties frequently malfunction and yet I do not suspect that they do’’ is ‘‘rather far away.’’ ‘‘In contrast, the possible worlds in which most of my testimonial beliefs are indistinguishably false—for instance, worlds in which I was raised by parents who belong to a cult, or worlds in which my government is highly corrupt, or worlds in which my society is highly superstitious—are much closer. Indeed, for many people, this is true in the actual world.’’ (190) Unfortunately, Lackey does not always practice what she preaches. There is a more reliable and easier empirical method for deciding issues in the epistemology of testimony. As Wilkes (1988) both argued and showed, scientific experiments and their theoretical results are more useful for deciding and resolving issues in the philosophy of personal identity than fantastic thought experiments. Historians, detectives, intelligence analysts, judges and juries are in the business of generating knowledge from mostly testimonial sources. Jurists and historians have developed over centuries theoretical and practical knowledge about reliable inferences from testimonies. Much of this knowledge is highly relevant for resolving the problems of the epistemology of testimony. Instead of thought experiments, the epistemology of testimony should be empirically founded on the solid practices of historians, detectives, jurists, and intelligence analysts. As Lackey notes, much of our knowledge has hybrid types of sources, combining empirical, inferential—a priori, testimonial, memorial, and introspective sources. However, some sources are more important than others for specific fields of inquiry. Obviously, empirical sources are more important for experimental science than other sources, most notably testimonial sources—nullius in verba. A-priori sources of knowledge are more important for logicians and mathematicians than other sources of knowledge. Memory and introspection are most important for people undergoing psychotherapy and for autobiographers. Testimony is most important for historians, intelligence analysts, detectives and jurists because they generate knowledge by and large, though not exclusively, from the testimonies of other people. The requirements for knowledge are more demanding in experimental science, logic, and historiography than in everyday life. The standard for knowledge in criminal common law is high, ‘‘beyond reasonable doubt,’’ and moderate, according to ‘‘the preponderance of evidence,’’ in civil law, which probably resembles the standard for testimonial knowledge in everyday life. The analysis of the professional practices of historians, intelligence analysts, detectives, and of evidence law should provide philosophers with models of the best practices for the inference of knowledge from testimonial sources.

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There is an obvious ontological gap between the epistemic practices of historians, detectives, investigative journalists, and jurists and Lackey and Goldberg’s analysis of thought experiments about testimonies and knowledge. The main thrust of Goldberg’s argument is the opposite of the argument of Lackey anti-transmission view, that the hearer’s knowledge depends on the reliability of the cognitive process that resulted in the testimony of the speaker. Yet, he uses the same thought experimental method as Lackey. Their basic units of analysis are of the speaker, the hearer, and the information or beliefs or knowledge that the hearer generates or receives from the speaker. Goldberg adds the cognitive processes in the mind of the speaker. Ontologically, this is a kind of epistemic atomism where the smallest unit of analysis has these three parts. Lackey recognizes that the epistemic context may affect the warrant to believe a testimony. She also insists that knowledge generated by testimony must also receive justification from another type of source (I actually disagree with this—more later). But her atomic epistemic unit is of a speaker and a hearer and the information that passes from the first to the second. Lackey’s atomic model is superior to many others in recognizing significantly that what passes from the speaker to the hearer is information that does not have to be in the form of belief or knowledge. This has significant implications for the epistemology of testimony. Still, in law, history, journalism and intelligence analysis the smallest units are made of multiple speakers, witnesses and testimonies, and hearers, communities of historians, jurors or judges, editorial boards, and teams of analysts. I do not go into the social aspect of the knowledge of the ‘‘hearers’’ here, the group rationality of historians, editorial boards, intelligence analysts, and detectives (cf. Sarkar, 2007) because I do not think it affects the arguments of Lackey substantially and it does not raise specific issues for the epistemology of testimony as distinct of other branches of epistemology. It is however crucially significant to note that no single testimony by any speaker is usually accepted as a sufficient source of knowledge by any historian, respectable journalist, intelligence analyst, or jurist. At least since Mosaic and Roman law, a single testimony is discounted: testis unus testis nullus, one witness is no witness. Nobody can be convicted on the sole basis of a single testimony. Historians rarely accept an uncorroborated testimony, and when it happens, it is because they cannot find any directly corroborating testimony. Reliance on single testimonies is at the heart of bad journalism and bad intelligence analysis. Graham Green in Our Man in Havana (1958) and John Le Carré in The Taylor of Panama (1996) satirized the ludicrous results of basing intelligence analysis on a single uncorroborated source: if an intelligence service believes a single agent who claims to have established a network without corroboration the agency may end up believing in giant vacuum cleaners in the mountains of Cuba or that Panama plans to sell its canal to the Chinese. At most, testimony from a single uncorroborated source about a ‘‘ticking bomb’’ may cause intelligence analysts to issue a warning and recommend taking defensive action out of caution, in case the testimony is true, without having to form any belief about its reliability. Historians, intelligence operatives, detectives and prosecutors spend much, maybe most, of their efforts and go to extraordinary lengths to discover multiple testimonies to the same events. The dozens of thought experiments that Lackey and Goldberg devised all assume a single testimony and testifier. These are not idealizations of reality, but oversimplifications remote from the testimonial epistemic world in which we live. 1. Against transmission Lackey argues that testimonial knowledge can be generated from speakers who do not possess that knowledge. Unreliable believers can be reliable testifiers. It is possible to communicate through statements and know from words rather than from

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expressions of internal states like intentions and beliefs. Lackey’s argument is based on the important recognition that what gets transmitted in testimony is information rather than beliefs or knowledge. People may transmit information without believing in it or even involuntarily. Lackey conducts thought experiments to prove her views. People who always lie may generate knowledge if their hearers know that they are consistent liars. A person with normal epistemic cognitive skills, who for some reason comes to believe falsely that their sense data processing skills are unreliable, may nonetheless report them. If the hearers believe these reports, they acquire knowledge. A similar thought experiment considers a Cartesian skeptic who has an undefeated defeater for believing in the external world (i.e. the skeptic has a reason that defeats the belief in the external world and there is no other reason to defeat it). A hearer may form knowledge on the basis of what such person reports without the undefeated defeater. In all these thought experiments a speaker transmits information to a hearer who received the information without its epistemic properties such as belief, epistemic context, and psychological defeaters. I think Lackey’s conclusions are correct. But do these thought experiments make the best case for them? There are no consistent liars in the world (not even politicians) because they would not be able to deceive and thus would gain no advantage from their lies. I cannot think of a real life case of somebody who distrusts their perceptions, yet reports them without comment. Much ingenuity and imagination went into devising these thought experiments. But I doubt they offer decisive intuitive disproof of the transmission of epistemic properties theory of testimony because they are too outlandish and as Faulkner (2009) showed, can be interpreted away. This is unfortunate because these thought experiments are unnecessary. Historiography offers many solid examples for the generation of knowledge from testimonies through the transmission of information that is not accompanied by the acceptance of its epistemic properties. Historians and detectives habitually extract information from testimonies of witnesses who had access to information they did not understand or did not believe in (Jardine, 2008). Lackey argues against the ‘‘sufficiency thesis’’ that takes knowledge by a speaker to be sufficient for knowledge by a hearer. She presents a thought experiment about a person who is compulsively trusting, a person who believes anything. Lackey does not mention it, but there is actually such a rare psychological disorder. Such a person would believe a reliable knowledge-possessing speaker. But since such a person would form true beliefs for the wrong reasons; these beliefs would not amount to knowledge. Another thought experiment to the same effect is of a hearer who seeks testimony from a target population and by sheer luck happens to ask the only reliable witness in the population and consequently forms true beliefs based on that person’s testimony. This, she argues, also falls short of knowledge. I agree with Lackey’s conclusion. Indeed, testifier’s knowledge is insufficient for the acquisition of knowledge by a hearer. But the subject of the first thought experiments is a person with a rare psychological disorder and I, for one, have ambiguous and conflicting intuitions about the second case. The thought experiment method is redundant because the very existence of specialized professions of historians, detectives, intelligence analysts & etc. with specialized knowledge and reliable truth conducive methods proves that hearers of testimony are not passive receivers of knowledge, transmitted from knowledgeable testifiers who are not sufficient for the generation of knowledge. Lackey rejects the interpersonal view of testimony that considers testimonies to contain assurances in addition to information. Many testimonies are unintentional and are not accompanied by any assurances. Lackey’s example is of soliloquies. I think that diaries and bureaucratic reports are even better examples because

they are not just paradigmatic cases of testimonial sources, but paradigmatic examples for highly reliable testimonial sources in historiography, more reliable than intentional testimonies that come with assurances. Further, argues Lackey perceptively, if testimony is a kind of evidence, it must be able to have an epistemic ‘‘common denominator’’ with non-testimonial evidence, for example when that evidence counters the testimonial evidence. Interpersonal testimony must somehow ‘‘play on the same field’’ of evidential warrant as all other sources of knowledge, but supporters of the assurance view do not suggest how to weigh such conflicting evidence. Finally, it is unclear how to evaluate the assurances of an unreliable speaker. Lackey concludes correctly in my opinion that testimonial assurances are epistemically vacuous. I should only add that some trial lawyers told me that reliable witnesses usually do not make assurances. When a witness guarantees the testimony or confronts the attorney saying ‘‘are you calling me a liar?!’’ The witness is often indeed a liar. 2. What is testimony? Lackey distinguishes what is testimony from what makes testimonies good or bad. In Lackey’s opinion excessively narrow characterizations of testimony failed to make the distinction and considered only good testimonies to be testimony proper. She criticizes the view that ‘‘S testifies that p if and only if S’s statement that p is an expression of S’s thought that p’’ (20). As a necessary condition, this is both too broad and too narrow. It is too broad in admitting statements that do not convey any information, such that it is a beautiful day, or Obama-like speech acts encouraging somebody to do something by saying ‘‘yes you can’’. It is too narrow in considering testimonies to be only what the witness intends to convey in statements. She is right to criticize the common thesis that ‘‘there is always a one-to-one correspondence between the explicit content of one’s testimony and what is being testified to’’ (26). She introduces thought experiments when the information that p is implied rather than explicitly stated in a testimony, for example, when one answers whether it is raining by stating where the umbrella is, implying that it rains and so the hearer may need an umbrella. Of course, historiography, detective work, and intelligence analysis may offer many more such examples (cf. Jardine, 2008). Lackey is right to focus on the transmission of information (as distinct from epistemic properties) as the main necessary condition for characterizing testimony. This fits with what Jardine (2008) calls the ‘‘genealogical’’ theory of testimony and the practices of historians, detectives and other experts who generate knowledge from information conveyed by testimonies. Some testimonies intend to convey non-p by means of saying p, for example in false confessions that include blatant falsities like the involvement of literary characters. Other testimonies may intend to say something else than p by means of p. Whether or not a statement or speech act transmits information depends on the hearers and their interpretative skills and background knowledge. Lackey introduces a disjunctive characterization of testimony, either concentrating on the intention to convey information or on the reception of information. The communicative act should mediate between the two. Either there is an expression of communicable content whether or not it is intended for communication (e.g. diaries); or the hearer reasonably (meaning normal hearer in similar circumstances) take the act to be conveying information by virtue of its communicable content. Lackey concludes that ‘‘S testifies that p by making an act of communication a if and only if (in part) in virtue of a’s communicable content, (1) S reasonably intends to convey the information that p or (2) a is reasonably taken as conveying the information that p’’ (35–36).

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Testifiers do not have to be sincere or competent to impart knowledge if their statements are reliable or truth conducive. If the hearer believes that p on the basis of the statement that p or ‘‘p is appropriately connected with the content of A’s statement’’ (76) and the hearer has no undefeated defeaters against p, the hearer has testimonial knowledge that p. The ‘‘appropriate connection’’ includes ‘‘nonverbal communication’’ and ‘‘pragmatic implicatures.’’ This appropriate connection is too vague. As Jardine (2008) noted about historiography, it is unclear whether we should consider paintings and other forms of symbolic but non-verbal remnants from the past testimonies. In a footnote (N. 27, page 30) Lackey recognizes that the boundary between knowledge that is testimonial and knowledge that is inferential is vague. I think Strawson (1994) was right to note that all testimonial knowledge must rely trivially on inference, perception and memory. To generate knowledge from testimony we must make inferences. But as Strawson noted, inference is not a basic source of testimonial knowledge. Likewise we must use perception to read or hear testimonies. But perceptions convey the words to us, they are not their source. Likewise we must rely on our memory for understanding sentences and then remember them when we put them together to generate testimonial knowledge. But our memories are not the source of knowledge. Lackey, like Plantiga (1993, p. 84) did not consider that the reliability of multiple testimonies may exceed any one of them, though this is glaringly true of legal testimonies and almost as patent for historical testimonies and the kind of unreliable testimonies journalists and intelligence analysts must use. To paraphrase Plantiga, testimonial warrant unlike water may rise higher than its source, when it has multiple sources. Lackey argues (94) that if a testimony is unreliable, insensitive, and unsafe, then the epistemic properties of the knowledge the hearer acquires must come from something other than the testimony, and so the hearer’s knowledge is not testimonial knowledge. Lackey is wrong because she does not consider that multiple independent unreliable testimonies can generate reliable knowledge because it is unlikely that they all agree on the same detailed testimony without a common cause. Courts convict beyond reasonable doubt regularly on the exclusive basis of the testimonies of criminals that are both unreliable, coming from criminals, and partly insensitive to initial conditions because state or crown witnesses have a strong personal incentive to offer damning testimonies to save their own skins (the details of their testimonies may be sensitive to initial conditions). Similarly, multiple testimonies from children are admissible whereas the testimony of a single child is not because it is not reliable (Coady, 1992, pp. 36–37). I discuss this at the end of this review. 3. Reductionism debate Reductionists from Hume to Faulkner and Fricker, interprets Lackey, interpreted the reliabilities of testimonies in terms of their correlations with reality. They reduced testimonial knowledge to its non-testimonial justification or warrant. Lackey endorses what I would call ‘‘reductionism-light’’ which she calls the Positive Reasons Thesis: ‘‘Justification or warrant is conferred on testimonial beliefs by the presence of appropriate positive reasons on the part of hearers. Since these reasons cannot themselves be ultimately testimonially grounded—otherwise there would be circularity, i.e., testimonial beliefs ultimately justifying other testimonial beliefs—they must depend on resources provided by other epistemic sources, which typically include sense perception, memory, and inductive inference’’ (144). Lackey considers the classical anti-reductionist counter-arguments: Children acquire knowledge from testimony but do not possess the relevant critical skills to evaluate reliabilities. It is

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difficult to assess reliabilities ‘‘one would have to be exposed not only to an appropriately random, wide-ranging sample of reports, but also to an appropriately random, wide-ranging sample of corresponding facts. Both are problematic. With respect to the reports, most of us have been exposed only to a very limited range of reports from speakers in our native language in a handful of communities in our native country.’’ (146) Some specialized testimonies may be too complex to check against the facts. Finally it may be difficult to infer from any generalization about the general reliability of a type of testimony anything about the reliability of a token testimony. Lackey replies that some justification of knowledge in addition to testimony is necessary. She illustrates this argument with a literally outlandish thought experiment about an alien dropping a diary written in English attesting that tigers ate members of that alien species on their home planet. Without additional evidence, and not just more testimonial evidence, arguably, it is impossible to know how to interpret such a diary. Any hermeneutic theory would be underdetermined: Do alien gavagais dream of electric tigers? Indeed, the reader of such a diary would need multiple sources in order to know how to interpret it. But Lackey dismisses the possibility that these other sources can be other testimonies. There is no need for thought experiments about aliens and tigers to see that she is wrong. An epistemic analysis of the practices of historians, archeologists and anthropologists who study texts, artifacts, or norms of alien cultures can demonstrate easily that they attempt to determine a theory of meaning for ‘‘alien’’ natural and conceptual languages by finding more relevant testimonies, such as other texts or more interviews to determine their interpretative theories. They do not resort, need to resort, or in the case of historiography can resort, usually to empirical non-testimonial or a-priori sources of knowledge. For example, historians can confirm that the Romans found physical deformity amusing exclusively on the basis of ancient testimonies, as alien as this perspective may appear to us today. Lackey presents her own approach to the reductionism/ antireductionism debate in the epistemology of testimony as synthetic or hybrid, combining reductionist and non-reductionist elements. She argues that B knows (believes with justification) p on the basis of A’s testimony if (necessary conditions): 1. 2. 3. 4.

B believes p on the basis of the content of A’s testimony. A’s testimony is reliable or otherwise truth conducive. B is a reliable or properly functioning recipient of the testimony. The environment in which B receives A’s testimony is suitable for the reception of reliable testimony. 5. B has no undefeated defeaters psychological or normative for accepting A’s testimony. 6. B has appropriate positive reasons for accepting A’s testimony. Again, the ontology here is atomistic, made of a single speaker and a lonely hearer. Though the formulation of condition 6, appropriate positive reasons, is sufficiently vague to accommodate multiple testimonies and a non-reductionist position, Lackey means a non-testimonial positive reason. I consider this condition to be redundant. A robust concept of reliability is pivotal at least for conditions 2 and 4. Philosophers like Plantiga (1993, pp. 78–82) and BonJour (2010, 155) questioned the availability of evidence for independently testing the reliabilities of many testimonies. Lackey retorts that there are more methods than the comparison of testimonies with facts to evaluate reliabilities of testimonies. She highlights the reliabilities of mundane testimonies like the time of day or one’s name and contrasts them with unreliable reports on the achievements of one’s children that tend to be exaggerated. It

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may be possible to attempt to generalize Lackey’s particular examples to generate general criteria or maxims for the reliabilities of types of testimonies, for example that testimonies whose speakers know are difficult to falsify tend to be reliable (like the time of day) or that when testifiers do not have a personal interest in the effects of the contents of their testimonies on their audiences, they tend to be reliable. Diaries and deathbed confessions are highly reliable because people have a reduced interest in deceiving themselves and in deceiving the world once the results of their confessions cannot affect them. Still, as Jardine (2008) demonstrated, finding universal criteria for the reliabilities of testimonial sources is neither easy nor simple. Following the genealogies of testimonies, their pedigrees, the historical process that generated them, is both simpler and conforms to the practices of historians and intelligence analysts in their assessments of the reliabilities of testimonies. Lackey emphasizes contextual factors in evaluating the reliability of testimonies. Lackey’s hapless example (181) is of choosing a random British newspaper as a reliable testimony when she visits the U.K. given all that she knows about British society. Clearly, Lackey does not know much about British journalism and has not spent time reading (or rather looking through) the most popular British newspapers such as The Sun and The News of the World . . . She is on firmer cultural footing distinguishing the American reliable National Geographic from the unreliable National Inquirer. Lackey probably intends to distinguish reputable newspapers in her media examples, excessively respecting the integrity of all British newspapers. But she does not consider what makes some news sources like The New York Times or The Washington Post more reliable than other newspapers or media controlled by authoritarian regimes or by interest groups that interfere with their editorial policies (and the same holds for intelligence analysis). Reliable newspapers and intelligence services follow institutional norms that generate reliable information from multiple testimonies; whereas unreliable newspapers publish, and unreliable intelligence services produce, reports that may be interesting or in somebody’s political or other interest, but do not follow a reliable protocol of comparing multiple sources. Reliability may not be in the context as Lackey puts it, but in the genealogy of the process of generating knowledge from multiple testimonies. Another example she brings for an unreliable type of witness is an alcoholic. A single alcoholic is indeed an unreliable witness. But ten alcoholics who testify to the same event are excellent testimonial sources for the generation of knowledge. Strawson (1994, p. 25) also argued for the significance of multiple testimonies. But Lackey, mistakenly in my opinion, rejects his arguments because she considers corroboration of testimony from multiple testimonies ‘‘circular.’’ But by circular arguments one usually means that parts of the argument logically entail each other. The viciousness of the circular argument is in begging the question, in the absence of any addition of new information. However multiple independent testimonies corroborate rather than entail each other. Multiple testimonies are no more ‘‘circular’’ than multiple replicated empirical experiments that generate support for a theory. Despite her rejection of the transmission theory of testimony, Lackey adheres explicitly to reductionist epistemic foundationalism that requires the informational-testimonial transmission chain to bottom out in one of the other four sources of knowledge. ‘‘[E]ven the final link in the chain can be partially indebted to testimony, so long as there is enough non-testimonial support to render it not irrational to accept the report in question.’’ (187) Lackey believes that many testimonies can be corroborated by independent observations. But historians cannot have independent observation, in principle, because history, past events, unlike its effects, is not observable. Nevertheless, historians are obviously able to generate reliable knowledge of the past, often exclusively on the basis of testimonial sources. In a larger epistemic context,

a coherentist account, generating knowledge from types of coherence between testimonies fits much better the practices of historians, journalists, intelligence analysts and judges and juries, as BonJour (2010, pp. 159–164) argued in general and Kosso (2001) showed in particular about testimonies about history.

4. Memory In an appendix, Lackey expands the conclusions she reached about the epistemology of testimony by inference and analogy to the epistemology of memory. She challenges the opinion of the likes of Audi and Plantiga that as much as testimony is about the transmission of knowledge, memory is about the preservation of knowledge; that neither testimony nor memory generate new knowledge and both require additional warrant from non-testimonial or nonmemory sources. Lackey argues correctly that memory, like testimony, can generate knowledge rather than just preserve it. Lackey shows that it is unnecessary to know at the time a memory or a belief is formed in order to come to know something later on the basis of that memory or belief. A psychological of normative undefeated defeater present while the memory or belief was formed may be defeated later, allowing the generation of new knowledge. Psychoanalysis for example promises the generation of such new knowledge from existing memories through the unblocking of psychological suppressions and inhibitions, undefeated defeaters. I should add that autonomous changes in our web of beliefs and memories may generate knowledge. For example, two or more memories that existed unlinked in our minds may become linked and generate new knowledge. A good detective story sometimes gives the readers all the clues necessary to put together the chain of events that led to and from the crime, though only the detective solves the mystery in the end because she is able to string these beads of information together. Then, the new beliefs that old memories generate may shed new light on existing memories and lead to their reinterpretation and the generation of new knowledge. We can also remember things without knowing them until the memories are triggered to generate knowledge. For example, in the novel, the Count of Monte Cristo was able to piece together the conspiracy that led to his imprisonment only years later, upon deliberating on his memories in his cell. Lackey is right to note that information stored in memory is not always in the form of belief or knowledge. But she does not cash out her notions of reliability of storage and retrieval, mostly because there is no simple storage of memory; the brain keeps working on our memories arranging and rearranging them, conflating and reconnecting them. Memories are active mental processes. This has led thinkers as different as Ranke and Freud to be highly suspicious of their reliability. Ranke excluded memoirs altogether as sources for writing historiography, privileging diaries, eye witness accounts and bureaucratic reports because they involve no or minimal reliance on memory as an epistemic source. Freud devised a method to deal with memory, but he cautioned that memory does not always distinguish representations of past events from fantasy. Psychoanalysts consider memories affective effects of their patients’ past, not representations of their pasts. Testimonial knowledge also must confront a problem of reliability. However, multiple independent testimonies consistently, repeatedly, and systematically generate reliable knowledge. An open question is whether multiple memories can or cannot operate in a likewise manner to generate reliable knowledge exclusively from memories. As in Lackey discussion of the epistemology of testimony, I agree with many of her conclusions and most of her criticisms of other positions in the epistemology of memory. But I find the thought experiments too outlandish to generate clear, distinct

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and unambiguous intuitions in support of those conclusions and criticisms. I suspect that these complex thought experiments are unnecessary because the psychology of memory must have generated a large volume of experimental and other empirical evidence that should be useful for deciding disputes in the epistemology of memory. A final critical note about Learning from Words is about its style rather than content. Dozens of philosophical positions are designated by original acronyms. This does not just give the book at times the feel of a military field manual, but more disturbingly disrupted the flow of reading, forcing me at times to go back to look for the meaning of the acronyms. It would have been best to avoid them altogether, or short of that, to add a glossary of acronyms for quick reference. 5. Relying on others Sanford Goldberg’s laudable project has been to attempt to revise Reliabilism to take into consideration that knowledge and the processes that generate it are social. Goldberg’s focus has been not so much on the epistemology of testimony as on its implications for epistemology in general, implications that most reliabilists have not considered. This has started in his previous book (Goldberg, 2007, pp. 133–238) with some discussion of the epistemology of testimony, and continues in this book with an attempt to revise Reliabilism to fit the observation that most knowledge results from the testimonies of others. Traditionally, Reliabilism considered only individuals receiving knowledge through a more or less reliable process. Goldberg comes close to supporting a version of the transmission of epistemic properties thesis that Lackey criticized. He argues that the hearer’s knowledge depends on the reliability of the cognitive process that resulted in the testimony of the speaker. He does not acknowledge that hearers can generate knowledge from testimonies as Lackey proposed. In a primal thought experiment Goldberg proposes to consider two truthful testimonies, one the result of sincere reporting by a reliable witness and the other the result of the witness’s unsuccessful attempt to deceive. He argues that the first case is of testimonial knowledge whereas the second results merely in true belief. I disagree with his conclusion that testimonial knowledge relies on the reliability of cognitive processes in other minds and epistemic individualism. Though Goldberg’s main thesis is the opposite of Lackey’s they both endorse the same epistemic atomism, taking the basic unit of the epistemology of testimony to be a speaker and a hearer. I think this atomism is wrong because only a small part of our testimonial knowledge is based on single testimonies. I would interpret both of the primal cases that Goldberg discusses as falling short of knowledge because of their reliance on a single testimony. Further, the evaluation of the reliabilities of individual testimonies is achieved often on the basis of their coherence with other testimonies rather than on the cognitive processes that produce them. Goldberg reacts to the arguments that the reliabilities of belief and testimony are independent of each other. The boy who cried wolf possesses a reliable belief, but does not convey a reliable testimony. Lackey’s example of a person who conveys a reliable testimony without believing in it like a creationist who teaches evolutionary biology also distinguishes belief from testimony. Goldberg debates the interpretation of the thought experiment that postulates a person who underwent two science-fictional brain operations and as a result always reports a deer when seeing one, while believing he has seen a horse. In his thought experiment, Goldberg adds two more brain surgeries to the poor patient to reach the intuition he desires about cognitive processes. I think that without knowing anything about the actual brain processes that generate beliefs and testimonies there is no limit to the

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content, complexity and outlandishness of these thought experiments. Anybody can add more complexities and outlandish conditions to generate a desired result. My own intuition, for what it is worth, is that the patient with the multiple brain surgeries never gets off the operational table, a victim of the philosophic imagination. The thought operations are successful, but the epistemic patient is dead. Goldberg attempts to use his concept of testimony to criticize aspects of classical Reliabilism that do not take testimony into consideration. He criticizes Alvin Goldman’s concept of justifiedness as resulting from dealing correctly with inputs from the environment. According to Goldman, justified belief results from successful cognitive processes, information processing, within the organism. Goldberg seeks to argue that this does not fit testimonial knowledge because of reliance on external cognitive processes transmitted from the speaker. He claims that the process reliabilist would also need to examine the reliability of the cognitive processes of other people, the testifiers. Goldberg wants to question the boundaries of the Cartesian subjects from their environments. Instead, Goldberg advocates a distinction between the cognitive and the ‘‘brutally causal’’. I sympathize with the attempt to break and cross the Cartesian boundaries. But I think the analysis of group rationality that Sarkar (2007) attempted is more promising than the blurring of the boundaries between testimony which is a type of evidence and the knowing subject. In the most common cases of testimonial knowledge, of multiple testimonies, their pedigrees, independence and correlation are more important for the generation of knowledge than the cognitive processes in the minds of the sources. Even in cases of single testimonies, the process reliabilist may evaluate the internal cognitive processes of the hearer that are applied for the evaluation of the cognitive processes of the speaker, for example, whether the hearer is gullible or critical, overly suspicious and distrusting or level headed. Alvin Goldman distinguished belief-independent justified beliefs whose input is not in the form of beliefs like inputs from the senses, from belief-dependent ones, like the conclusions of deduction. Goldberg argues that the inputs for the process of inferring from testimonies include the processes that led to them in other minds. He acknowledges Lackey arguments that the beliefs of the testifier are not the input for the output of testimonial knowledge. He asks ‘‘in what sense can testimony, which is not a kind of belief, be the input into a belief-dependent process?’’ His answer is that there should be a more liberal understanding of belief-dependent process. Separately necessary and jointly sufficient conditions for ‘‘liberal’’ belief dependence or ‘‘quasi-belief dependent are: ‘‘. . . a cognitive process the reliability of whose outputs are a function of the reliability of its inputs . . . These inputs [must] be assessable in terms of their reliability. . . an input satisfies this condition only if it is itself the output of a cognitive process (process type) whose reliability can be assessed in its turn’’ (72). The result is what Goldberg calls the ‘‘extendedness hypothesis,’’ testimonial belief formation is an interpersonally extended process. Goldberg replaces beliefs with the outcomes of cognitive processes. But such outcomes need not be beliefs at all. He assumes that testimonial beliefs involve no process of inference and the reliability of the output depends simply on the reliability of the input. Inference from multiple individually unreliable testimonies show clearly the severe limitations of this approach. It is possible to infer highly reliable and justified beliefs from multiple testimonies of unreliable witnesses like children, criminals and drunkards. Like Lackey, Goldberg subscribes to foundationalism in claiming that: ‘‘reliabilist epistemic assessment is assessment of all the processes on which the subject epistemically relies; in these cases the process extends as far as the subject’s epistemic reliance extends’’ (92). This statement comes close to Jardine’s (2008) genealogical

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model with a greater emphasis on psychological cognitive factors. Tracing the genealogies of testimonies may indeed be important for assessing their reliabilities. But this tracing is neither possible in some cases, nor necessary in many other. What we need in the case of multiple testimonies is just to ascertain that the processes extending backward from them do not converge in which case they are not independent (Jardine, 2008, pp. 170–171). For example, all my beliefs about Mongolia have exclusively testimonial sources. I judge that among the many sources for my beliefs about Mongolia there are a sufficient number of sources that are independent of each other, yet are coherent and consistent. That is enough. I do not need to examine the processes that led to the testimonial sources that affected me, examine whether they have all been to Mongolia and under which circumstances. In the case of historical events like the storming of the Bastille, most people, who are not professional historians who specialize in studying the French Revolution, read multiple secondary sources and assume that they relied on multiple primary sources they are not acquainted with. We rely on others like historians and journalists because we trust that they adhered to reliable institutional norms and preferred practices for inference from multiple testimonies. We do not need to examine these cognitive processes for ourselves. Historians employ transparent processes of inference that are traceable through their footnotes which most readers do not bother with, so readers should be able to follow the primary sources referenced to in the footnotes if they wish to check them for themselves. By contrast, the process of inference from multiple testimonies in journalism is deliberately opaque. Since the sources are secret, we cannot follow the process of inference to assess it. Instead, readers must rely on historical evidence for the institutional norms of quality newspapers that generate reputation. For example, The Washington Post has maintained a good record for following these methods of inference from multiple testimonies, even when their identity is secret. Goldberg rebuts the argument that assessment of others’ cognitive processes is not a part of the epistemology of testimony by mentioning the tracing of the pedigrees of testimonies. This ‘‘genealogy’’ is indeed practiced by historians, intelligence analysts, and journalists (Jardine, 2008). But this tracing implies a critical approach to sources and a separation between the individual knower and the testifiers rather than a single extended process. Often, the primary purpose of the tracing is to assure that the testimonies were independent of each other and if they were not, to try and make sure that they preserve information about a past event that happened prior to their intersection. Goldberg proposes the following thought experiment: Suppose ‘‘either you can have access to the ‘individualistic’ facts regarding the hearer, those that determine the global reliability of the processes though which she comprehends testimony and scrutinizes it for credibility; or else you can have access to the ‘extended’ facts (those regarding the hearer’s informant), those that bear on the global reliability of the testimony proffered on this occasion’’ (144). Goldberg thinks the obvious choice is the second because ‘‘the facts in the ‘individualistic’ set are valuable only as indicating the likelihood of something that the ‘extended’ facts themselves would directly establish: namely, the de facto reliability of the testimony . . .’’ (144) Goldberg suggests that since most people have no access to information about the chain of testimony, they must satisfy themselves with assessing the hearer. This could fit the situation of people who read newspapers. However, most people who read historiography have the choice and they make the first choice. Though the testimonies historians use are transparent, most consumers of historiography prefer to know what the historian, the expert in generating new information from old testimonies by evaluating their reliabilities and comparing them to each other, generated from the sources. Only producers of testimonial

knowledge like professional historians, intelligence analysts, detective, and journalists would rather make the second choice and trace the sources as Goldberg suggests. The interesting and original penultimate chapter is devoted to ‘‘coverage reliability’’, the inferences people make from the absence of testimony. Background information and theories may lead us to expect that had something been the case we would have heard about it through our epistemic community. This has the simple form of modus tollens: Had p been the case, I would have heard it by now in testimony t, -t, hence -p. For example, had the unemployment rate fallen sharply, I would have heard about it from the kind of media sources I am exposed to regularly. I did not, hence it did not. This proves that epistemic reliance on others goes beyond the testimonies they convey to their silences. While original in the context of the epistemology of testimony, a similar sort of argument is familiar from discussions of evidence in general, e.g. the case of the dog who did not bark in the night (or in a psychological and existential contexts in Ingmar Bergman movies and Samuel Becket plays). Goldberg attempts to formulate the conditions of reliable beliefs that are based on the absence of testimony. He suggests five jointly sufficient conditions: 1. Source-existence: there should be a group that would report on an event should it happen, like the media or a gossiper. This can also be generic, non-specific, group. 2. Reliable-coverage condition: the source would investigate and reliably determine whether p. It should then reliably report it in timely fashion, for example, The New York Times. 3. There should be sufficient time for investigation. 4. Silence, no testimony to that effect. 5. Reciprocity: The receiver of the information should be attuned, e.g. read the newspaper regularly. Goldberg’s discussion here is particularly good because instead of thought experiments, he considers quality journalism. However, he leaves out of his discussion the conditions of reliable coverage, what are the institutional practices of quality newspapers like the New York Times that make them usually reliable? What are their institutional norms for inference from multiple testimonies and for avoiding certain biases, e.g. by erecting ‘‘Chinese Walls’’ between the advertisement, news, and editorial departments of the newspaper. Goldberg argues that this kind of knowledge from the absence of testimony is based even less than normal testimony on any individual’s autonomous cognitive achievement. Goldberg is right that in the process of inference from silence, various social practices and institutions are relied on. Social practices change in time and vary from place to place. The hearer of silence needs to be attuned to these variations and ‘‘calibrate expectations’’. I think that this requires even greater expertise of institutional reporting practices, the sort of wisdom that historians possess. Historians need to know bureaucratic norms to know what the silence of the records mean. For example, some historians attempted to discover to what extent did the thirteen colonies trade with each other and to what extent they were trading with the British mother country before 1776. They examined the records of the port of Philadelphia and discovered that most of the registered ships were ocean liners trading between Britain and its colonies. However, another historian noted that the port of Philadelphia officials were registering only ships above a certain size. Most of the ships that served coastal trade between the colonies were smaller and hence were not registered. So, the silence of the Philadelphia records about intraAmerican trade has no testimonial value. Similarly, different countries have different norms of journalistic reporting. In some countries, fatal car accidents are reported on the top of the news; in others they are not, so the absence of news of car accidents do

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not imply the local safety of this mode of transport. For example, few people note that 30,000 people die each year in car accidents in the United States, ten times the number of victims on 9/11. The last chapter of Relying on Others attempts to synthesize, following Goldman, Reliabilism with social epistemology. In a potentially significant note Goldberg promises to pursue in the future the application of networks theory to epistemology to mediate between epistemic holism and individualism. Meanwhile, he argues that epistemic focus on individuals would provide us with finer resolution of processes than social epistemology, but individualistic epistemology would miss the big picture of trends and large processes. He is right that the epistemology of testimony demonstrates that Process Reliabilists should be interested in social institutions and practices that affect the reliability of belief formation processes directly or indirectly. Goldberg argues that the degree of the need to manage critically incoming testimonies corresponds with the environment. In a totally trustworthy social context, credulity would be a reliable epistemic policy and vice versa in an unreliable environment. However, Goldberg does not consider how can and do we come to consider an epistemic testimonial environment reliable or not in the first place. In a footnote (1, on page 80), Goldberg refers to Friedman’s (1987) Bayesian article about hearsay that traces the reliabilities of testimonies. Beyond this awareness of a Bayesian approach to the epistemology of testimony, Goldberg and Lackey did not explore the implications of Bayesian probability on the epistemology of testimony. In conclusion, allow me to sketch it in a genre Lackey and Goldberg would appreciate, the thought experiment: Imagine that we know there was a lottery draw yesterday. The lottery was fair and each of the numbers from 1 to 100 had an equal chance to be the winning number. We do not know which of the numbers from 1 to 100 won. We have one witness who was present when the lottery took place. Suppose this witness is a semi-catatonic mental patient. We evaluate his reliability in this matter at about 0.1 (or 10%). After some prodding (he is semi-catatonic), he tells us that a particular number between 1 and 100 was drawn and was the winning number. What is the posterior probability that the number he testifies to has indeed won? If we plug these numbers into the Bayesian theorem, the computation is simple: The likelihood of the testimony given that it is true is the reliability of the witness, 0.1. The prior probability of any number from 1 to 100 being the winning number is 0.01. The expectancy of the testimony given that it is either true or not is (0.01  0.1) + (0.9  0.01) = 0.01. The posterior probability that the testimony is true then is 0.001:0.01, or 1:10. This fits nicely with the transmission of epistemic properties or the extendedness thesis because it is identical to the reliability of the testimony which we stipulated at 1:10. The reason is that when the prior probabilities of any number in a fair lottery are identical, posterior probabilities reflect the ratio of likelihoods; we can ignore the priors. Note also that there is nothing ‘‘special’’ about the number that the witness testifies to; it could have been any other number between 1 and 100. The reliability of the witness is the determining factor in the evaluation of the reliability of the testimony, and this reliability reflects the quality of the cognitive processes in the witness’s mind. But a Bayesian ‘‘miracle’’ takes place if instead of a single semicatatonic witness with a low reliability of 0.1, we have three semi-

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catatonic mental patients each with a 0.1 reliability who testify that the same number was drawn in the lottery. Since they are semi-catatonic we presume that they have not been influencing each other’s testimonies (they can communicate only with great difficulties and after repeated prodding). The likelihood of the testimonies multiplied by the prior is 0.13  0.01 = 0.000001. The expectancy is 0.000001 + [(1:99  0.9)3  0.01]. The posterior probability of the testimonies of the three semi-catatonic mental patients then is close to 0.99, knowledge itself! The reason for this escalating posterior probability is the incredibly low likelihood that all three independent witnesses would both be deceiving (intentionally or not) and then choose the same number from among 99 possible false numbers. The prior likelihood of the particular number the witness testifies to is insignificant in the case of a single witness (just as the degree of detail of a single testimony does not affect its reliability; fraudsters attempt to convince by spawning elaborate yarns to increase the impression of reliability, but that is a logical fallacy) But when there are multiple independent testimonies, the particular number the witnesses testify to is significant (just like the level of detail of a testimony matters when there are multiple witnesses who agree) because of the low likelihood of agreement on it, given that the independent witnesses are false. This is how testimonial knowledge is habitually generated by inferring from the testimonies of unreliable but multiple independent witnesses. The transition from a single testimony to multiple ones is also a transition from the transmission of epistemic properties to the generation of knowledge from individually unreliable testimonies. I think that since most of our testimonial knowledge belongs to the second generative type, this is what the epistemology of testimony needs to understand and indeed be about. References BonJour, Laurence (2010). Epistemology: Classic problems and contemporary responses (2nd ed.). Lanham Maryland: Rowman & Littlefield. Coady, C. A. J. (1992). Testimony: A philosophical study. Oxford: Oxford University Press. Faulkner, Paul (2009). Review of learning from words: Testimony as a source of knowledge. Mind, 118, 479–485. Friedman, Richard (1987). Route analysis of credibility and hearsay. Yale Law Journal, 96, 667–742. Gendler-Szabó, Tamar, & Hawthorne, John (2010). The real guide to fake barns: A catalogue of gifts for your epistemic enemies. In Tamar Gendler-Szabó (Ed.), Intuition, imagination, and philosophical methodology (pp. 98–115). Oxford: Oxford University Press. Goldberg, Sanford C. (2007). Anti-individualism: Mind and language, knowledge and justification. Cambridge: Cambridge University Press. Green, Graham (1958). Our man in Havana. London: William Heinemann. Jardine, Nick (2008). Explanatory genealogies and historical testimony. Episteme, 160–179. Kosso, Peter (2001). Knowing the past: Philosophical issues in history and archaeology. Amherst NY: Humanity Press. Le Carré, John (1996). The tailor of Panama. London: Hodder & Staighton. Peijnenburg, Jeanne, & Atkinson, David (2003). When are thought experiments poor ones. Journal for General Philosophy of Science, 34, 305–322. Plantiga, Alvin (1993). Warrant and proper function. Oxford: Oxford University Press. Sarkar, Husain (2007). Group rationality in scientific research. Cambridge: Cambridge University Press. Strawson, P. F. (1994). Knowing from Words. In Bimal Krishna Matilal & Arindam Chakrabarti (Eds.), Knowing from Words: Western and Indian philosophical analysis of understanding and testimony (pp. 23–28). Dordrecht: Kluwer. Wilkes, Kathleen V. (1988). Real people: Personal identity without thought experiments. Oxford: Clarendon Press.