Keeping epistemic justice social Bennett Holman (Yonsei University) Justin Bruner (Australian National University)

1. Introduction Recently, epistemologists and philosophers of science have begun to acknowledge the

importance of better understanding the inner workings of epistemic groups. This is in part due to the fact that in a wide variety of contexts, knowledge is produced, shaped and processed by multiple agents, often working in tandem, embedded in a particular social or institutional setting. For instance, scientific communities involve a large number of inquirers who collaborate and share discoveries with each other against the backdrop of an array of community-wide norms governing (among other things) credit allocation. These considerations have led philosophers such as Alvin Goldman to advocate a ‘systems-oriented’ approach to social epistemology (Goldman, 2010), in which the lone inquirer is replaced by a group of inquirers as the unit of analysis, and the primary task of the social epistemologist is to better understand how various ways of structuring communities lead to better or worse epistemic groups.

Goldman’s call to arms crystalizes the spirit of a number of earlier works. Koppl, Kurzban and Kobilinsky (2008), for instance, discuss how certain evidence gathering and assessment processes employed by many legal institutions may systematically lead to biased results. Zollman (2007, 2010) employs a simple agent-based simulation to explore the effect communication structure has on the reliability of a group of inquirers. Strevens (2003) develops a formal model of scientific inquiry to argue that the prevailing norms governing credit allocation in science result in an efficient allocation of cognitive labor across scientific projects. Subsequently, systems-oriented social epistemology has become a rapidly growing sub-field of philosophy and has successfully drawn on a slew of methods and techniques to tackle a variety of pressing issues (e.g. Grim, et al., 2013; Holman & Bruner, 2015; Forthcoming; Hessen, Forthcoming; Mayo-Wilson, Zollman, & Danks, 2011).

Yet, as Goldman himself acknowledges, there is an ethical dimension to this brand of social epistemology that is often overlooked. Namely, certain ways of structuring epistemic communities appear to be ethically problematic. Consider, for instance, a scenario in which women and racial minorities are incorrectly denied credibility and as a result are neither trusted nor deferred to in epistemic matters. While the most influential works on the importance of diversity have focused the argument on how a lack of diversity can be epistemically undesirable (e.g. Hong & Page 2004), the epistemic marginalization of minorities has also recently been widely recognized as a serious ethical issue worthy of discussion.1 This is in large part due to Miranda Fricker’s highly influential groundbreaking 2007 Epistemic Injustice: Power and the Ethics of Knowing.2

Fricker (1998; 2007) identifies testimonial injustice as a distinct form of epistemic injustice (i.e. cases in which individuals are harmed in their capacity as a knower). Testimonial injustice supervenes on three more primitive concepts. First, an agent is said to have rational

1 We say these ethical issues have only recently been widely recognized because, as Rachel McKinnon (McKinnon, 2016) rightly notes, there has been a long and somewhat ignored tradition going back to at least the 1980’s in black feminist thought exploring the contours of epistemic injustice. 2 For a summary of the epistemic injustice literature see McKinnon (2016)

authority if she is competent and trustworthy. That is, she must be able to determine what the truth is, and she must be willing to share it. If a person is treated as trustworthy and competent, she is said to have credibility, irrespective of whether she is in fact a reliable source of knowledge. A person suffers a credibility deficit when they are denied credibility despite having rational authority. Identity prejudice occurs when one person makes an evaluative judgment about another merely on the basis of some fundamental aspect of their social identity (race, gender, class, etc.). According to Fricker, testimonial injustice occurs only when a person who has rational authority is deprived credibility (i.e. suffers a credibility deficit) as a result of identity prejudice.

In what follows, we situate Fricker’s basic notion of testimonial injustice within the systems epistemology framework. We conceive of our exploration of epistemic injustice as ‘systems-oriented’ in the sense that we attempt to outline somewhat general conditions under which an epistemic system will likely result in widespread testimonial injustice. In doing so, we argue that the same mixture of methods (formal modeling, computer simulations, case studies, etc.) that have been successfully employed by systems-oriented social epistemologists can also be fruitfully utilized to better understand the ethical consequences of various ways of structuring and organizing epistemic communities.

We proceed first by appealing to a case study in the medical sciences before turning to a simple formal model of group inquiry that allows us to precisely track the credibility assignments of agents over time. We find that large swaths of the population can suffer from a testimonial injustice under conditions we contend are likely to hold in many epistemic communities and unanticipated by Fricker: namely, when certain actors are bestowed an inappropriately high level of trust and authority from their peers. We conclude by examining the grounding of Fricker’s conception of testimonial justice. Here we argue that Craig’s (1990) minimal epistemic society requires our more expansive notion of testimonial justice.

2. DES: Autopsy of a Miracle Cure In 1966, Charles Brenton Huggins was awarded the Nobel Prize in medicine for his

discovery of a hormonal treatment for a previously terminal form of prostate cancer. His drug of choice was a synthetic estrogen called Diethylstilbestrol (DES). First synthesized in 1934 by Sir Edward Charles Dodd, it was originally developed for a variety of menstrual problems (Meyers, 1983) and was one of a number of treatments that emerged in the heyday of endocrinology prior to the discovery of penicillin and other antibiotics. While some endocrine products were clearly quack remedies (e.g. Mark White’s Goat Gland Goiter Serum) contraindicated by medical evidence (CPC, 1916), others (e.g. insulin) were some of western medicine’s first miracle cures. DES is an excellent reminder that drugs can be both poisons and cures. While its use in prostate cancer saved lives, its use as a prophylactic for miscarriage destroyed them.

Five to ten million women took DES as a prophylactic in the US alone (IARC, 2012). At least a quarter of DES daughters (i.e. women who were exposed to DES in utero) developed structural abnormalities in their genital track (Kaufman, 1982) and are twice as likely to miscarry (Kaufman et al., 2000). Their rate of developing clear cell adenocarcinoma—a cancer which virtually never appears in women under 40— is 16 in 10,000, forty times higher than in unexposed women (Troisi., et al., 2007). DES sons also have a higher likelihood of genital abnormalities (15%-32% vs. 5%-8% in unexposed men). Both men and women have higher rates of cancer (see Reed and Fenton (2013) for a summary of the recent literature of health

effects). If mouse studies are applicable to humans, there will be health consequences in the third-generation as well, but these cohorts are just beginning to reach the age where such effects can be assessed (CDC, 2012). Ultimately, we will argue that, contra Fisher & Apfel (1984), this tragedy was not an unavoidable consequence pushing the boundaries of medical knowledge; rather it occurred due to a credibility excess within a community of knowers.3 DES was approved by the FDA in 1941 to treat the symptoms of menopause, yet not all of the research on DES was favorable. The drug caused a number of unpleasant side-effects including vomiting and indication of damage to internal organs. These results, coupled with animal studies showing that DES was carcinogenic, led the American Medical Association’s Council of Pharmacy and Chemistry to warn that “because the possibility of harm must be recognized, the council is of the opinion that [DES] should not be recognized for general use.” (CPC, 1939, p. 2312).4 Despite the early warning signs, once approved, companies began exploring numerous other possible uses for DES. This process was intensified by the introduction of competing treatments for menopausal symptoms that caused fewer side-effects (Langston, 2010). In keeping with common practice, manufacturers would send out free samples, encouraging doctors to use it in areas the company thought would be helpful. For example, in 1943 McNeil Laboratories were encouraging doctors to experiment with “prostate cancer, ‘feminine psychosis,’ nausea and toxemia of pregnancy, miscarriages, extrauterine retained placenta, infantilism, amenorrhea or hypoplasia of the genitalia or breasts, and even herpes” (Dutton, 1988, p. 46). While not the first to support the use of DES as a prophylactic for miscarriage, Harvard professors Olive and George Smith provided both the reputation and the research that would earn the FDA’s approval for such use in 1948. Pertinent to our discussion here, it is worth noting that their evidence was largely based on a large, but uncontrolled case series (Smith, 1948). Though acceptable evidence by the regulatory standards of the days, other researchers insisted that without randomization and a placebo, the Smiths’ work was insufficient to establish efficacy. Between 1950 and 1955 a raft of double-blind randomized controlled trials were conducted showing that DES was either ineffective at preventing miscarriage, or actually may induce them (Davis & Fugo, 1950; Dieckmann, et al., 1953; Ferguson, 1953; Reid, 1955; Robinson & Shettles, 1952; Swyer & Law, 1953). As the FDA did not remove DES from the market, it was up to the individual doctor to decide what was best for their patient. Though the use of DES peaked in 1953, it remained prevalent for the next two decades. By the time the product was withdrawn from the market in 1971 no less than 3% of American children had in utero exposure to DES (Meyers, 1983). Moreover, the market withdrawal was instigated, not by mounting evidence of ineffectiveness, but by the discovery of a link to a rare form of cancer (Adenocarcinoma). But as carcinogenic risks had been established in the scientific literature long ago, the historical question is what explains why an ineffective and dangerous drug was used for over two decades. Below we will consider a number of possible

3 Other accounts, especially Gillam & Bernstein (1987; but also Langston, 2010) have taken issue with the history offered by Apfel and Fisher. Rather than a general rebuttal of their account, our purpose will be to focus in on the credibility economy of the medical community, especially the consequences of credibility excesses. 4 See Gillam and Bernstein (1987) for a detailed account of early DES studies.

factors, specifically: medical research; expert opinion; a physician’s clinical experience (or that of his colleagues5); and the influence of pharmaceutical manufacturers. As discussed above, had doctors attended to the first possible source of information, studies published in medical journals, DES would have fallen out of use shortly after it was introduced. The largest, most rigorous study compared 1646 women randomly assigned to either DES or placebo and found the drug to be ineffective (Dieckmann, et al., 1953). No contravening evidence had been produced by 1967 when the National Academy of Sciences assembled a panel of experts who rejected use of DES on the basis of the literature or in the four years that it took for the FDA to revoke its approval. The second possible source of information (expert opinion) is somewhat more complicated. Olive and George Smith continued to stand by the use of DES even as negative evidence mounted (Dutton, 1988). However, despite some initial enthusiasm, expert opinion was against the use of DES to prevent miscarriage. Early on the editor of the prominent Year Book of Obstetics and Gynecology recommended against use of DES until more data was gathered (Greenhill, 1949). An opinion that was echoed by the Journal of the American Medical association (JAMA, 1949). As noted above, the data subsequently collected did not support the use of DES. Moreover, the lack of support amongst elite physicians was known to the manufacturers of DES, a fact uncovered in subsequent litigation by subpoenaing internal memos. For example, one read:

I got into a discussion today at Jewish Memorial Hospital with a group of outstanding Gyn. And Obs. men… These men are all of the opinion that the Smith and Smith approach to the problem of threatened abortion with increasing doses of [DES] is of no value at all. Dr. Goodfriend has been in touch with outstanding men all over the country and he says they all hold the same opinion. (Sider, 1950, quoted in Dutton, 1988, p. 58).

Further, doctors that were cognizant of the animal studies, had long been worried about DES and thought the research done in the early 50s had “driven a very large nail into the coffin… of [DES]” (Greene, commenting on Ferguson (1953, p. 601)). Yet, it seemed that many rank-and-file practitioners remained unaffected by the medical elite. On the other hand, it has been well documented that the prestige of the Smiths did impact their local medical community so much so that the disorders caused by DES exposure were sometimes called “the Boston disease.” Similarly, Heinonen (1973) noted that the usage of DES increased the closer one got to Harvard. Given the sizable evidence arrayed against their position, it seems reasonable to claim that the Smiths were attached to the veracity of their procedure well beyond what could be reliably substantiated. Moreover, the effect of deference to the Smiths can be seen in the community surrounding Harvard. Indeed, in a discussion of the Dieckmann et al., (1953) results that demonstrated DES to be ineffective, one OBGYN retorted

5 Here we are deliberately using the male gendered pronoun. It has been suggested that sexism may be at the root of the tragedy. Specifically, in personal communication Heather Douglas has suggested that this may represent a case where values illegitimately played a direct evidential role. She suggests that doctors may have used causal reasoning based on an overly simplified notion of femininity, viz. giving birth is an essentially feminine activity and thus providing women with more of a female hormone (DES) will increase their ability to enact their femininity (i.e. giving birth). We believe that such an account can’t be the whole story as it fails to explain many details of the case (e.g. increased use around Boston) as well as a more general phenomena of the continued use of obstetric procedures demonstrated to be ineffective (e.g. oxygen therapy for premature infants (Silverman, 1980)). Nevertheless, nothing in this account rules out sexism as a contributing factor.

“As a former Bostonian, I would be entirely lacking in civic loyalty if I had not used [DES] in my private practice” (Irving, as quoted by Gillam & Bernstein (1987)). We shall return to this response in the discussion, but it is worth noting that this cannot explain the nation-wide use of DES. The third possible source of information about the efficacy of DES is the experience of the doctor or the doctor’s colleagues. Of course, in isolated cases, because of the lack of controls in clinical practice, a doctor may have had a string of successful births and mistook this as a treatment success. However, given the fact that DES was ineffective or harmful, such unlikely events cannot explain why DES was so widely used. Apfel and Fisher (1984) suggest that the use can be explained by a general enthusiasm for new treatments and thus a biased tendency to see outcomes as successes. However, enthusiasm does not spontaneously emerge and in this case, there was only one source of information that was uniformly and ubiquitously in favor of the use of DES: medical information disseminated by pharmaceutical manufacturers. Pharmaceutical manufacturers have a number of ways of communicating with doctors, but perhaps the most central are detailers. Paid by pharmaceutical companies to travel to doctor’s offices and provide the “details” of the company products, detailers were both ubiquitous and a trusted source of information (Greene, 2004). As the vice president of Schering Corp. noted, “We believe in the preeminent importance of detailing. We believe that our trained, highly professional sales representative is the most capable medium we have of persuading the physician to prescribe our products and the pharmacist to stock them” (Hearings, 1962, pt 14, p. 8219).6 While influential, such “highly professional” reprsentatives did not have rational authority. As Harry Dowling—one of the premier pharmacologists of the day— noted in his senate testimony:

Detail men are valuable for the purpose of getting information to the physician and the pharmacists regarding the availability and the prices of products distributed by their companies, but being salesmen, they cannot be expected to give unprejudiced advice. Not being physicians, they cannot instruct physicians regarding the basic principles upon which the use of new drugs is based. (Hearings, pt. 24, p. 141772).

Yet despite this seemingly common sense attitude, rank-and-file doctors did trust detailers to provide information. Asked about which sources of information were important to their prescription decisions, one doctor responded:

Detailing is of prime importance. I don’t understand the attitude of the doctors who push the detail man aside and refuse to listen to him. The detail man is an excellent source on indications [i.e. what to prescribe a drug for] and contraindications, dosages, and comparison between products. (Hearings, pt. 2 727)

Another doctor testified: “I think of the detail man not as a salesman, but more a friend and educator who can give out technical details” (Hearings, pt. 2, p. 729). Of course, some doctors did recognize detailers as biased; however, a study conducted in 1951 found only 14% of doctors were unfavorably disposed to detailers (Caplow, 1952). Indeed, the most comprehensive 6 These hearing were convened to examine the pricing practices of pharmaceutical companies and led to the 1962 Kefauver-Harris amendment establishing the modern FDA.

contemporaneous study on the influence of detailers found that, “when the discussion is confined to the commercial sources, detailing is reported to be the most worthwhile by about twice as many doctors as name all other methods combined” (Gaffin and Associates, 1958, p. 726).

Thus, we may say that though doctors were awash in information that contraindicated the use of DES, the fact that widespread use continued was the result of information distributed by pharmaceutical manufacturers, most centrally through the testimony of detailers. However, because detailers continued to promote DES even when DES was demonstrated to be ineffective, they lacked trustworthiness and thus did not have rational authority. Moreover, as Dowling’s testimony reminds us, detailers were generally untrustworthy regarding the efficacy of the drugs they promoted. Nevertheless, doctors treated detailers as credible (i.e. good informants) despite their lack of rational authority and hundreds of thousands were injured thereby.

3. Modeling the credibility economy In what follows we draw on previous work by Bennett Holman and Justin Bruner (2015)

who extend a model of network epistemology due to Kevin Zollman (2007, 2010). We contend that the formal model of inquiry explored by Holman and Bruner provides us with a precise way of discussing the credibility economy, thereby allowing us to determine under what circumstances epistemic injustices are likely to arise. In particular, we illustrate how the assignment of a credibility excess can prevent a person with rational authority from transmitting her knowledge.

We begin with a model of inquiry explored by Kevin Zollman (2007, 2010). In Zollman’s original model a group of agents are all tasked with determining which of a variety of actions is more likely to result in success.7 Actions correspond to a variety of phenomena such as the administration of a drug treatment or the application of a particular scientific theory or methodology. An action is ‘successful’ if, in the former case, the treatment leads the patient to recovery or, in the latter case, use of the theory or methods in question results in new insights. Agents endeavor to determine which of the various ‘actions’ available to them are more likely to lead to success and gather information about these actions by performing them (i.e., administering a particular drug treatment, for instance). Individuals are modelled as Bayesian learners who update their beliefs regarding the efficacy of various actions in response to new evidence. Like a doctor ethically bound to take the action she believes is best for her patient, agents can not take the action they think is less effective, just to gather better information about it. However, they may learn about the other action from experiences of other agents in their epistemic community with whom they share their results. Zollman has shown via simulation that in this baseline model there is an interesting trade-off between speed (the time it takes for the community to reach consensus) and reliability (the likelihood that the community achieves a true consensus).

Zollman’s model has been highly influential in social epistemology and has provided philosophers and social scientists with a means of tractably exploring the effect communication structure has on the reliability of group inquiry. We consider one extension of this framework first explored in Holman and Bruner (2015). In particular, Holman and Bruner relax the assumption that network structure is fixed. Recall that in Zollman’s original model of network

7 This basic framework, as we will demonstrate, can be easily modified and complicated to handle more realistic settings.

epistemology, agents update their beliefs on the basis of their experience as well as the experiences of those they are connected to in a social network. Furthermore, the original model assumes that agents weigh their experience and the experience of their peers equally. As a result, agents are essentially forced to adjust their beliefs in light of the findings of their peers. This may not be particularly problematic if agents are epistemically interchangeable. Yet in many instances, individuals are not equally capable of determining efficacy (consider, for instance, two scientists who are not equally skillful in their application of a scientific theory or method), nor is it always the case that all agents sincerely report their findings to others. For these reasons, individuals may benefit from cutting ties with certain agents and establishing new connections with those who are both competent and sincere. Holman and Bruner (2015) consider a novel network formation rule which allows agents in the epistemic network to forge, as well as cut, ties with peers. Individuals assign their peers a credibility score which in part determines the level of influence their colleague’s findings have on their beliefs. Those with a higher credibility score are more influential than those with a measly credibility score. Additionally, they allow individuals to differ in their credibility assignments, meaning two agents can both assign a different credibility score to a third party.

Recall that in this model of network epistemology agents are continuously gathering information and updating their beliefs regarding the efficacy of various actions. Agents are also updating the credibility score they assign to their peers. Agents who report results that are implausible given what the focal agent currently believes are seen as less credible in the eyes of the focal agent. Furthermore, agents who repeatedly report implausible results can lose all credibility (e.g. Matilda who told such dreadful lies, it made one gasp and stretch one’s eyes). Note that there is a potential for a positive feedback loop here, as the listener’s beliefs are in part influenced by the reports of the speaker. In the limiting case in which the speaker is the only agent the listener attends to, the speaker is almost always bound to be considered highly credible in the long run as their reports slowly shape the belief profile of the listener. Things are much more complicated, however, when multiple agents are involved and individuals play the dual role of listener and speaker. In these scenarios, it is not uncommon for an agent to receive no credibility at all from their peers, despite the fact that they are both sincere and competent.

This is clearly illustrated in Holman and Bruner (2015), who consider the introduction of a so-called ‘intransigently biased agent’ to the above set-up. This actor is insincere and systematically misreports their experiences to others so as to overstate the efficacy of a particular action. Holman and Bruner attempt to determine whether the remaining sincere individuals can learn to disregard the reports of the biased agent, and thereby minimize the deleterious effect dishonest agents have on the epistemic community. They find that in many cases, a large number of honest actors assign a high credibility score to the biased agent and no credibility at all to other honest individuals in the epistemic community.

In these cases, individuals are systematically ignoring the experiences of those who are both sincere and competent. This unfortunate state of affairs obtains for the following reason. A number of agents initially assign a credibility excess to the biased agent. The biased agent’s high credibility score means the hearer’s beliefs are heavily influenced by biased reports. Yet shifting her beliefs in response to the reports of the biased agents only widens the gap between the reports of honest agents and the focal agent’s beliefs, resulting in the hearer lowering the credibility score she assigns to honest agents. This, in turn, means honest agents have even less influence on the beliefs of the hearer in the future, resulting in a positive feedback loop where many honest agents in effect lose all credibility in the eyes of the hearer. This is obviously not

only problematic for epistemic reasons, but for moral reasons as well – competent and sincere individuals are denied all credibility, resulting in the speaker being undercut in her capacity as a knower.

Before moving on, it might well be worth attempting to address the foreseeable concerns some may have with the above model. For example, both Coady (1992, p. 210) and Fricker (2007, p. 75f) reject the idea that there can be a precise science of credibility or some exact “credibility ratio.” Fricker elaborates that her concern is that “the sheer range of contexts to which the ordinary human hearer needs to be sensitive in her credibility judgements is so vast… that it is simply not realistic to think that any sufficiently complex codification will be available” (p.75). Instead of applying some formula, she maintains credibility judgments happen reflexively and intuitively.

As a descriptive fact about credibility judgments, Fricker is certainly correct that people do not calculate credibility scores. Whether hearers would be better off if they did is an empirical question and there is considerable evidence from numerous other domains that statistical prediction rules are superior to expert judgment (Bishop & Trout, 2002). But more to the point, the purpose of formal modeling is not to capture every single nuance, but to expose simple mechanisms that can account for the observed phenomena. While we believe that the modeling work of Holman and Bruner (2015) clarify the dynamics of the credibility economy, the argument does not rest on it alone. For those who reject such modeling, we believe—as supported by the case studies—that the general argument goes through if the reader will grant us: (1) that credibility comes in degrees; (2) that people’s credibility can increase and decrease depending the track record of their past testimony; and (3) the extent to which a piece of testimony influences a hearer’s belief depends in part how credible she believes the speaker to be.

4. Collateral Epistemic Injustice In both the case study and the model above, we have seen how intransigently biased agents affect the dynamics of epistemic communities.8 Below, we will take advantage of systems oriented social epistemological framework to address the nature of epistemic injustice. We take issue with Fricker’s (2007) contention that epistemic injustice only occurs when a person who has rational authority is deprived credibility (i.e. a credibility deficit) due to an identity prejudice. She argues that credibility excess does not result in injustice, because credibility is not a distributive good and thus fairness norms do not apply. Rather injustice occurs when “someone is wronged specifically in her capacity as a knower” (Fricker, 2007, p.20).

Fricker (2007) considers the case where someone is granted more credibility than they merit and asks what wrong has been done. She reasons that if a person is over esteemed, the typical results of this credibility excess will be in her favor, she will be more likely to receive good employment, respect, and status. Even if by some bad break the credibility excess leads to misfortune, the recipient of a credibility excess has not been undermined, insulted, or otherwise been denied proper respect “qua subject of knowledge; so in itself it does her no epistemic injustice” (Fricker, 2007, p.20). The wrong done in a case of epistemic injustice, at least as far 8 In the DES case study, detailers, but not the Smiths seem to intransigently biased. Whereas the Smiths scaled back their position over time, the detailer that wrote the memo disclosing the fact that elite physicians nation-wide had found Stilbetin (his company’s proprietary name for DES) was ineffective at preventing miscarriage, ended the memo “For myself, I’m still plugging Stilbetin” (Quoted in Dutton, 1988, p. 58).

as Fricker is concerned, occurs when the hearer denies the speaker “her capacity as a giver of knowledge” (p. 44). Because a credibility excess facilitates the speaker’s ability to transmit knowledge (to the extent they have any knowledge to transmit), Fricker argues that a credibility excess does not constitute epistemic injustice.

What is clear from Fricker’s description is that she is focused on the two-person exchange at a given moment in time. Here, we might agree that the credibility excess does not result in an epistemic injustice to the speaker, but this is not to say no epistemic injustice occurs at all. Fricker’s (1998, 2007) account is grounded in Craig’s (1990) state of nature story in which a community of agents is involved in acquiring knowledge. Similarly, Fricker’s primary examples of testimonial injustice (i.e. Tom Robinson from To Killing a Mocking Bird and Marge Sherwood from The Talented Mr. Ripley) are not scenarios involving a mere two-person exchange. The jury is not merely weighing Tom Robinson’s testimony, but his testimony and that of Mayella Ewell. Likewise, Herbert Greenleaf hears the testimony of Tom Ripley in addition to Marge Sherwood on a number of occasions.

Elsewhere, Fricker (2008) has stressed the importance of expanding the boundaries of epistemology to encompass both (a) multiple agents and (b) a temporal dimension. We argue that such an expansion entails the fact that while credibility excess does not result in direct testimonial injustice (i.e. injustice to the recipient of the credibility excess), it does (typically) result in collateral injustice (i.e. other members of the epistemic community are systematically undercut in their capacity as a knower). Below we identify both diachronic and synchronic forms of collateral injustice. The diachronic credibility economy is prominently illustrated in the DES case example. Recall that numerous sources in the epistemic community, sources like University of Chicago Professor William Dieckmann, whose large and methodologically rigorous study appeared prominently in the American Journal of Gynecology and Obstetrics, should have transmitted the knowledge that DES was ineffective (it certainly should have done so in light of every other similarly rigorous study testifying to the same conclusion).9 Doctors who rejected the ability of “science” to determine efficacy and who put their trust in the “art” clinical experience would have been informed by expert clinicians that DES was “of no value at all.” Even those doctors who only trusted their own clinical experience lacked any evidence that DES was effective. For most doctors, the reason that any and all of these credible sources failed to transmit the knowledge that DES was ineffective was the long-standing credibility excess enjoyed by detailers. If we consider the credibility economy in this situation we find a case where agents with rational authority are making a claim (e.g. DES is ineffective and harmful) and this claim is contradicted by agents without rational authority. Moreover, detailers are not hidden among doctors, they are a distinguishable group of testifiers and thus bear what Fricker (1998) terms “working indicator properties.” An epistemically responsible hearer would not have assigned the detailer a high level of credibility; they were wolves in wolves clothing. Yet doctors took detailers to be their “friends and educators” and to be an “excellent source on indications.” As Podolosky (2014) has documented, one consequence of the repeated divergence between clinical researchers and pharmaceutical companies was the development of prejudice against clinical researchers which in turn functioned to blunt the effect of their testimony.10 For 9 Fricker (2007, p. 27) is clear she considers writing a form of testimony 10 The power dynamics of this case are complex. While it is true that such researchers would eventually have hermeneutic power to construct notions like “efficacy” that would eventually be used by the FDA to regulate

example, consider the popular reaction when the FDA considered removing a fixed-dose combination antibiotic from the market in 1963. The FDA convened a panel of experts to assess the product led by the eminent clinical pharmacologist Harry Dowling. The panel concluded that the evidence that the drug was effective was questionable and even if some of the subcomponents like caffeine provided symptomatic improvement, “in no instance was there justification for any such product to contain an antimicrobial agent” (Dowling, as quoted by Podolsky, 2015, p. 89). When the FDA decided to remove the product from the market on this basis, they received 7,500 letters decrying the tyranny of the “ivory tower.”11

This rhetoric had emerged among some doctors as a result of repeated disagreements between clinical pharmacologists and pharmaceutical companies. Early on one leading medical expert of the day worried that there was a growing group of doctors he called “Professional Illiterates” who “sneer at the ‘Ivory Tower Boys’ who ‘just don’t realize what the practice of medicine and the problems clinical research amount to’” (Lasagna, 1955, p. 185). While it is no doubt the case that some clinical research lacked a sufficient appreciation for realities of daily practice, the blanket use of the term “ivory tower boys” constitutes a slur that simultaneously marks out group allegiance and a judgment about university researchers (Camp, 2013). That said, as far as slurs go, it is an odd one indeed

On a first pass the slurs used to attack clinical researchers and their “test tube” medicine, can be seen as a form of epistemic resistance against those in positions of power. By identifying researchers with the “ivory tower,” rank-and-file doctors acknowledge that clinical researchers have a certain refined sort of knowledge, but also confine that knowledge to a domain that is irrelevant to their daily practice. Thus, in one fell swoop, there is first a sort of deference, and then an “othering” that banishes a potential community member that would otherwise have rational authority to challenge the doctor’s beliefs.

This othering can be most clearly seen in the way that clinical researchers attempted to resist the process. One such attempt is plain in William Hewitt’s (founder and chief of the infectious disease division at UCLA) 1969 congressional testimony on fixed-dose combination antibiotics:

I would like to emphasize that I am not an ivory tower basic scientist…. I have had a practice of my own for 20 years and even to the present rely on this type of activity for one-third the income I derive from professional activities… [the members of this committee] were not sitting in libraries writing textbooks and giving lectures to medical students but rather were daily seeing sick patients… All of us participate in liberally in local and national societies, membership of which consists largely of “general physicians” concerned with both general and specific medical problems. Quoted in Podolsky, 2015, p. 122

Interestingly, Hewitt doesn’t claim that his evidence is based on clinical experience, rather his emphasis on clinical practice is an attempt to be seen as a part of the ingroup whose testimony cannot be ignored because of his social identity. Indeed, he goes so far as to explicitly invoke market entry (Carpenter, 2010), they lost credibility among many rank-and-file doctors and thus in the short-term, suffered from a credibility deficit in their testimonial exchanges. 11 For example, a specific attack on Harry Dowling (University of Illinois) who among his many credential was chairing the AMA council of pharmacy and chemistry, which established, in large part, to determine treatment efficacy read as follows: “I question whether the honorable emeritus professor of medicine [presumably Dowling] has seen a patient in person from or in his ivory tower for some time. However, in my 22 years of vigorous practice…” (Quoted in Podolsky, 2015, p. 124)

membership in the same professional societies. Despite such attempts to maintain credibility, over the course of the 1950s and 1960s, repeated conflicts between products promoted heavily by pharmaceutical companies and opposition by clinical pharmacologists led to so many disputes that officials at the FDA worried that there would be a complete bifurcation between academic researchers and practicing physicians.

The modeling work of Holman and Bruner (2015) suggests one way that such bifurcations can come about. In a group where initial credibility assignments include a credibility excess to a biased agent (i.e. an agent with mere credibility), a hearer receives conflicting testimony. Even supposing that both sources are given credibility initially (i.e. there is no initial credibility deficit), in repeated interactions the two speakers begin to acquire track records and these track records inform the credibility assignments of the listener. If the credibility excess granted to the biased agent is sufficiently large, the hearer will end up with beliefs that mirrors the biased agent’s and be at odds with the experiences of the speaker who actually possesses rational authority. The latter’s accurate and forthright testimony will increasingly appear biased and implausible. This, in turn, will lead to corresponding gradual loss of credibility.

In some cases, as in Fricker’s honest used-car salesperson, a person suffers a credibility deficit that does not constitute an injustice. In this case, the speaker uses a reliable stereotype to assign low credibility to the salesperson. Fricker contends “the hearer cannot be blamed for the grounds of her flawed credibility judgment” (2007, p. 42) since the stereotype she leans on is generally reliable–it is just an unfortunate accident, but not an injustice, that this rare honest salesperson is denied credibility. However, in the case under consideration, the hearer may well be blamed. In Fricker’s claims the ethical aspect of testimonial injustice “derives from some ethical poison in the judgement of the hearer” (p. 22), in her central cases, this ethical poison is prejudice. We assert the ethical poison here is the hearers extreme negligence in their credibility assignments, specifically in the credibility excess that doctors assigned to detailers. Detailers bore working indicator properties that should have led an epistemically responsible doctor to give them little credibility. Their epistemic negligence thus infects the resulting credibility deficit and makes it a case of collateral epistemic injustice.12

5. Ne Quid Nimis Originally, Fricker (1998) maintained that either a credibility deficit or a credibility excess could result in testimonial injustice. Fricker (2007) retracted the claim, explaining that

as I was working on the book, however, I gradually came to the view that while it is certainly true that credibility excess is an epistemic dysfunction (knowledge is attributed where there is none), and while there can of course be cases of credibility excess that are zero sum so that one person’s excess is another’s deficit, it is only the cases of deficit that constitute a testimonial injustice. That is because in a case of credibility excess no one need be wronged; no one insulted, discriminated against, or otherwise undermined in their capacity as a knower. Fricker, 2010, p. 164

12 Note, that this is not (merely) a case where the testimonial injustice damages the epistemic system, this is a case where a person has been denied their status as a subject of knowledge.

The crucial shift for Fricker, was her new commitment to claim that credibility is not a finite good; as such, notions of distributive justice do not apply (Fricker, 2007, 19-20). Fricker reminds us of Hume’s lesson that in circumstances of abundance, concern with distribution does not arise (Hume, 1739/2000). Instead, Fricker grounds her argument in the claim that the wrong of epistemic injustice “wrongs someone in their capacity as a subject of knowledge, and thus in a capacity essential to human value; and the particular way in which testimonial injustice does this is that a hearer wrongs a speaker in their capacity to give knowledge, as an informant” (p. 5).

Fricker is clear: Because credibility is not a finite resource, a credibility excess to one informant doesn’t take away credibility from another. Though it might be epistemically dysfunctional on the part of the hearer, so long as a speaker that has rational authority is recognized as credible, no one is denied a capacity essential to human value. Without the later there is no epistemic injustice and a fortiori no testimonial injustice. However, we claim that if we return to Craig’s state of nature story (the grounding of Fricker’s account) we will see that credibility excesses cannot be ignored. In brief, the function of Craig’s (1990) state of nature story is to articulate the necessary qualities of the minimal epistemic community, that is, a group of people who can successfully discover truths about the world by interacting and pooling their information. As Fricker (2007) construes it, there are two values that apply to speakers: the ability to determine the truth (Accuracy) and the willingness to convey it (Sincerity). The third value applies to the hearer and it is one that is such that “hearers or inquirers in the State of Nature will need to be open to truths offered to them by their peers, and to be open without being credulous of testimony that is in fact false” (p. 114). She notes that because there will be a division of labor in the State of Nature, hearers will have to employ stereotypes to make credibility judgments. Moreover, some of these credibility judgments will wrongly deny credibility to those that have rational authority, and thus if a hearer wishes not to miss out on truths that would otherwise be available they will have to develop an anti-prejudicial sensitivity and Fricker names this virtue Testimonial Justice. What then does Testimonial Justice amount to? If, as it seems, that Testimonial Justice is the inverse of Testimonial Injustice, then a hearer must avoid assigning a credibility deficit to a speaker with rational authority. One sure fire way to do that is to trust everyone, but of course such a hearer would be credulous of testimony that is in fact false. To avoid that, a hearer must also avoid giving credit where credit is not due, that is they must avoid both credibility deficits and credibility excesses if hearer is to fulfill their role in the pooling of knowledge. If that’s the case, and it seems that it must be, Fricker is wrong to single out the avoidance of prejudice as constitutive of Testimonial Justice. The motivation of the virtuous hearer must be to assign credit in proportion to a speaker’s rational authority.13 It might be contested that on a charitable reading of Fricker, prejudice can result in both credibility excesses and deficits. If so, then Testimonial Justice is indeed the avoidance of prejudice. This reading seems hard to square with Fricker’s claim that testimonial injustice only occurs from credibility deficits, but irrespective of what the right reading is, the avoidance of prejudice is insufficient as a regulatory ideal for Testimonial Justice.

13 Alternatively, if the purpose of the state of nature story is just to show that Fricker can recover the anti-prejudicial virtue in the state of nature, then our argument shows that we can similarly recover our more expansive virtue (i.e. proportionality). Candidly, we have doubts about the value of such just-so stories; we offer the argument here to show that if this is the kind of justification one plumps for, it is available for our account as well.

We grant that identity-based prejudice may be a particularly pernicious and important form of prejudice and that prejudice is one way that credibility can fail to be assigned in proportion to rational authority, but an unprejudiced hearer does not necessarily assign correctly assess credibility. A careless assignment of credibility may function in just the same way. So too would the unprejudiced dupe and so on. Just as the virtue of Accuracy homes in on what is strictly required of the speaker, we claim that the hearer who has the virtue of Testimonial Justice is distinguished by the fact she takes great care to learn the markers of rational authority and that she is motivated to assign credibility proportionately. Above we have argued that collateral epistemic injustice is a diachronic phenomena, below we argue for a type of synchronic collateral epistemic injustice—injustice that occurs when the hearer has failed to exhibit the virtue of proportionality.

Such case can be seen in Dr. Irving’s reception to the Deickmann et. al., (1953) results. Recall that confronted with the facts that the recommendations of Harvard professor’s Olive and George Smith are both unfounded and contradicted by superior evidence, Dr. Irving responds, “As a former Bostonian, I would be entirely lacking in civic loyalty if I had not used [DES] in my private practice.”14 It goes without saying that “being from Boston” is not a stereotype that reliably sorts good informants from bad informants. The fact that he esteems the Smiths to such a degree causes him to dismiss contravening evidence. To use DES on the basis of the Smiths endorsement is to simultaneously ignore the editors of the Journal of the American Medical Association (JAMA, 1949), the editor of the American Year Book of Obstetrics and Gynecology (Greenhill, 1949), and the criticism contained in the commentary of the Smith’s presentation of their evidence (Smith and Smith, 1949; see especially, Dieckmann, Page and Allen). Moreover, assuming that out of a sense of civic loyalty Dr. Irving continued his use of DES after hearing the testimony of Dieckmann this would be yet another case of synchronic testimonial injustice.15 A number of aspects of this case are worth mentioning. The first is that unlike the previous case, Dr. Irving neither dismisses the specific evidence that Dieckmann presents nor does he call into question Dieckmann’s status as a knower by classifying him as an ivory tower boy. In other words, Dieckmann does not suffer a credibility deficit. Instead Dr. Irving amplifies the credibility of the Smiths to such an extent that epistemically superior contravening testimony of Dieckmann fails to convey knowledge. It seems that Dieckmann has been wronged as a speaker in his capacity to give knowledge, but without a credibility deficit, Fricker’s account cannot account for this. Our alternative construal of Testimonial Justice accounts for the injustice committed by Dr. Irving. He grants that Dieckermann is a credible source, but— motivated by civic pride— he assigns a credibility excess to the testimony of the Smiths and as a result prevents Dieckermann from transmitting knowledge.16 According to Fricker, the unjust denial of a capacity to transmit knowledge is an unjust denial of a capacity essential to human value, and thus, despite their being an absence of a credibility deficit, Dr. Irving’s actions result in a testimonial injustice because he has failed to exhibit the virtue of proportionality.

14 We will charitably assume that Dr. Irving believed, on the basis of the Smiths’ testimony, that DES was safe and effective, rather than far more grotesque view that Dr. Irving believed that DES was unsafe and ineffective, but prescribed it to his patients nonetheless. 15 Though we don’t know whether Dr. Irving continued to use DES, it has been established that proximity to Boston increased the likelihood of doing so. Irrespective of whether Dr. Irving reformed his personal practice, thousands of doctors did not. 16 The extent to which it is intelligible to talk about degrees of credibility will be considered in section QQQ

Again, the modeling work of Holman and Bruner (2015) clarifies the analysis. Fricker is absolutely correct that qua hearer an agent has an unlimited amount of credibility to assign. However, qua believer the agent must somehow weigh all of the different sources of information in order to update their current beliefs in light of the new evidence. Usefully we might distinguish between credibility and influence. As the hearer considers the testimony of a larger number of people with equal credibility, the influence of each of the individuals is decreased. Thus, while credibility is not finite, influence is, and thus the norms of distributive justice do apply.

If the hearer is virtuous (as we defined above) then each speaker will influence the hearer in proportion to the speaker’s rational authority. On the contrary, if the hearer assigns credibility wantonly, a speaker with rational authority can be drowned out and prevented from transmitting knowledge. This point has been anticipated by Elizabeth Anderson, who notes that in contexts where “one person’s word must be weighed against another’s […] credibility excess granted to one speaker may be a testimonial injustice against the other” (Anderson, 2012). We are in agreement and take the simulations of Holman and Bruner (2015) to demonstrate the mechanisms by which widespread harm can result when certain individuals are inappropriately elevated as epistemic agents. In this case, because the wronged party is not immediately involved in dyadic relation that is the cause of the injustice, it constitutes a case of synchronic collateral epistemic injustice.

6. The Ethics of Gaslighting In closing, we note that it has not escaped our attention that one of the features that may seem to give rise to collateral epistemic injustice is the inability for the individual to simply determine which of the conflicting reports is correct. If, confronted with two opposing testimonies, a hearer could simply verify which account was correct, there would be no credibility excess and thus no collateral injustice.

Be that as it may, there will certainly be cases like this even in the state of nature. Just because I fail to catch my prey does not mean the person who testified that the location is a good hunting ground was misleading me, some things are just uncertain. Moreover, the agents in Holman and Bruner’s model are able to access reality in just this way. Indeed, one of the results they highlight is that an agent that assigns the intransigently biased agent a credibility excess may come to doubt her own capacity as a knower. Fricker notes a similar harm can be caused when credibility deficit is internalized. Perhaps the best reason to countenance both excess and deficits as injustice is that they can produce all the same harms.

For all this, Fricker holds that credibility excess is merely epistemically rather than ethically problematic. Only if prejudice poisons the credit economy is it injustice. Yet consider one of the most famous representations of the potential harms of credibility excess in the classic movie Gaslight. In the film, Gregory Anton systematically drives his wife (Paula) insane first by isolating her from the outside world and next by frequently telling her (and the house staff) that she is forgetful, anxious, and acting strangely. He subsequently steals things from her and accuse her of losing them. For all intents and purposes, Paula's epistemic world is confined to Gregory, and to a lesser extent Elizabeth (the cook), and Nancy (the maid). Because of the credibility excess assigned to Gregory by the other inhabitants of the house, all three become convinced that Paula is indeed losing her mind. This all despite the fact that all three had initial evidence to the contrary. Early on in the process, Nancy questions Elizabeth in the Kitchen:

Nancy: She looks 'ine to me, is she really sick

Elizabeth: I dunnow. Not s’far as I can tell, but the master keeps tellin' 'er she is. If we examine the credibility economy we find that early on each woman in the house assigned to Gregory a credibility excess despite visible evidence he was untrustworthy. As a result, they each participated in (and suffered from) synchronic collateral testimonial injustice (they couldn’t transmit their knowledge that Paula was sane). As a result of a repetition of such events, Paula becomes the victim of diachronic collateral testimonial injustice, losing all credibility with the staff (who subsequently dismiss her claims that the gaslight dims each night, a real phenomena caused by the actions of Gregory). Paula not only loses her confidence in herself as a knower, she actually begins a process of coming to resemble Gregory's characterization (viz. she starts to in fact become anxious, act strangely, etc.).

Focusing on only Nancy and Elizabeth for a moment, there is no doubt that the credibility excess that Gregory enjoyed stemmed from living in a class-based, patriarchic society. For Fricker, it is these prejudices that make it a case of epistemic injustice. If the situation had been different and the credibility excess had come about merely because Elizabeth and Nancy were careless or lazy with their credibility, Fricker would classify it as an epistemic dysfunction, but not injustice. In contrast, we take seriously the ethical fundamentality of a person's status as a knower. Accordingly, if Nancy and Elizabeth's lapses in epistemic judgment were due to extreme carelessness rather than social prejudice, we assert that their actions would be even more blameworthy and the injustice suffered by Paula would remain. We contend that it is proportionality that is the prime virtue of testimonial justice and that it is missing in both cases. Finally, given that proportionality is the characteristic virtue of Testimonial Justice, credibility excesses matter to the ethics of knowledge and this should remain clear as long as we keep epistemic justice social.

7. Technical appendix

Here we present a precise formal framework that can help us better understand the influence that credibility excess can have on an epistemic community. In particular, we examine a network of individuals all confronted by the so-called bandit problem, a situation in which one is presented with two slot machines and must determine which to play. Zollman suggests this is analogous to a doctor determining which of two medications to administer.

Doctors are modeled as Bayesian learners, who update their belief when presented with new evidence, and are myopic in the sense that they simply administer the drug they believe is more efficacious. Moreover, there is no guarantee that an individual doctor will correctly identify the more efficacious drug. Consider the following scenario: a doctor has observed 5,566 successes upon administering drug A 10,000 times, and only 10 successes upon administering drug B 20 times. In this case our agent will believe drug A is superior, but clearly since comparatively little is known about drug B, the optimal long-run strategy may include

prescribing it to gain more information. The myopic doctors considered in the course of this paper, however, will only begin to prescribe B if the success rate of A falls under 50%.17

In our model, the doctors do not know the true success rates of drugs A and B. In each interval doctors administer the drug they believe to be superior to their N patients—where each patient has probability pA (or pB) of recovering—and record what percent recover. Doctors are embedded in a social network and treat results obtained by their neighbors on par with their own experience. As Figure 1 indicates, epistemic agents are represented as nodes in a graph and those nodes connected by a line are said to be “neighbors.”

Figure 1. Each node is an agent and in Zollman’s model each line represents a two-way communication channel between the agents. We relax this assumption and allow for asymmetric connections.

With the society of knowers in view, we can now ask some interesting questions; chief amongst them, how should the group communicate in order to maximize the likelihood that every member will learn which drug is superior? While agents in the maximally connected graph reach consensus more quickly, the agents in the cycle are more likely to reach a true consensus (Zollman, 2007). This counterintuitive finding occurs because, as connection density increases, the entire group is likely to be converted from the superior option by a chance wave of bad results. By contrast, the cycle promotes situations in which the group as a whole stays undecided for longer and there is at least one member collecting data on each option, a phenomenon Zollman (2010) calls “transient epistemic diversity.”

Holman and Bruner (2015) showed that these results only hold so long as agents are epistemically pure. Generally speaking, an impure agent is an agent interested in convincing the group of a view irrespective of the truth. An epistemically impure agent in the medical field is an agent, such as a pharmaceutical company, who attempts to encourage doctors to use a drug irrespective of which drug is more efficacious. In our simulations, epistemically impure agents

17 Myopia is plausible in several cases including where a doctor feels ethically prohibited from giving a patient a drug perceived to be worse just to increase the doctor’s confidence the drug is inferior.

administer only their favored drug and the results they obtain are produced by a biased distribution. So, if the actual probability of success is 56% and the bias is 10%, the impure agent reports data as if the probability of success is 66%. Specifically, their data comes from a binomial distribution with a mean of 56%+b, where b is the strength of the bias. This is our attempt to capture, in our idealized model of medical epistemology, the fact that pharmaceutical manufacturers find numerous ways to subtly bias their results.

We focus primarily on the “worst case scenarios” in which the pharmaceutical company promotes the inferior drug and is connected to all doctors. Briefly, the exact set-up is as follows. Agents are randomly assigned beliefs regarding the two available drugs. Doctors, as well as the biased agent, administer the drug they believe to be most efficacious. This generates N data points, and all share their data with those they are connected to. Doctors then update their beliefs in a fashion outlined by Zollman (2010) and then repeat this process.

In addition to Zolman’s basic model, we include a means for agents to assign each other (and themselves) a credibility score. Modeling network formation is an active area of research in a number of disparate fields.18 Unfortunately, none of the canonical models can be appropriately applied to our epistemic community because our agents are continuously generating data. As in Zolman’s model, a doctor i is connected to doctor j if i is somehow influenced by the experimental findings of j. However, in this model, network connections now vary continuously and are no longer symmetric, meaning that i can be strongly connected to j, while j is only weakly connected to i. In this case, i is strongly influenced by j while j is only slightly influenced by i. Similar arrangements no doubt do occur as when the work of a senior scientist is very influential on a junior scientist, but this influence is not reciprocal. In general, j assigns more credibility to i if i’s experimental findings are somehow in line with j’s subjective beliefs. Likewise, j assigns less credibility to i the more that i’s experimental findings seem to clash with j’s beliefs. Making this precise is difficult and highlights why many models of endogenous network formation used in economics and sociology are not applicable when thinking about our epistemic network. Our model of endogenous network formation replicates basic hypothesis testing inside an epistemic community of agents continuously experimenting. Consider a network of D doctors. Each doctor has D+1 bins (one for each doctor and one for the detailer (i.e. the biased agent)) that initially have anywhere from zero to 100 balls in them. Let Bi be the vector < 𝑏𝑖1, 𝑏𝑖2, … , 𝑏𝑖𝐷+1 > where bi1 is the number of balls in agent i’s first bin. These bins correspond to the credibility that a doctors assign to the testimony of their peers. As such credibility comes in degrees, and just as Fricker (2007) notes, credibility is not finite. If a speaker demonstrates they are reliable, the hearer can add balls to the speakers bin (i.e. assign them more credibility) without altering the bins of any other agents. Yet there is a significant difference between credibility and influence. Supposing that there is only one credible agent, they have both full credibility and full influence. However, supposing that four more equally credible agents are added to the community, the influence of the first agent will clearly decrease to 1/5th of what it was before. Thus, when updating beliefs we need a measure of influence and this measure needs to take into account the relative credibility scores. Specifically, how much influence agent j has on agent i is determined by the proportion

18 See Jackson (2005) for an overview.

𝑏𝑖𝑗∑ 𝑏𝑖𝑘𝑘∈𝐷+1

⁄ . This measure of influence determines how much weight i puts on the

experimental findings of j (call this wij). Agent i updates her beliefs regarding drug A as in Zollman (2010), except the results are weighted as follows: P (drug A works | agent j has s successes in N trials) = (α + wij s) / (α + β + wij N) where α and β are the agent’s values from the previous round. Ceteris paribus, the more balls agent i has in her jth bin, the more credibility she assigns to agent j and thus the larger impact agent j has on i’s beliefs. Individuals adjust their connections in the following fashion. Upon receipt of N data points from agent j, agent i conducts a one-sample t-test based on her subjective beliefs. Let tij be the t-score agent i assigns to agent j’s experimental results in round r. The number of balls in bij is then updated by the following equation:

𝑏𝑖𝑗(𝑟 + 1) = 𝑏𝑖𝑗(𝑟) + 𝑓(𝑡𝑖𝑗), 𝑤ℎ𝑒𝑟𝑒 𝑓(𝑥) = Λ(1.96 − |𝑥|) and Λ > 0.

Where bij (r) is the number of balls in agent i’s jth bin at round r. Thus a t-score with an absolute value less than 1.96 results in an increase in the number of balls in the bin, while a t-score with an absolute value exceeding 1.96 results in a decline. One intuitive property this update rule satisfies is the following: if you are influenced by two individuals and they repeatedly provide you the same evidence then in the long run you should expect to assign these two individuals equal credibility. One’s initial credibility assignments “washes out” in the end.

References

Anderson, E. (2012). Epistemic justice as a virtue of social institutions. Social Epistemology, 26(2), 163-173.

Bishop, M. A., & Trout, J. D. (2002). 50 years of successful predictive modeling should be enough: Lessons for philosophy of science. Philosophy of Science, 69(S3), S197-S208.

Camp, E. 2013, “Slurring Perspectives,” Analytic Philosophy 54.3, 330-349. Caplow, T. (1952). Market attitudes: a research report from the medical field. Harvard Business

Review, 30(6), 105-112. Carpenter, D. (2010). Reputation and Power: Organizational Image and Pharmaceutical

Regulation at the FDA. Princeton: Princeton University Press. CDC. Center for Disease Control and Prevention. DES Update: Consumers. 2012

http://www.cdc.gov/des/consumers/index.html. CPC, Council of Pharmacy and Chemistry (1916). “Mark White Goiter Serum and Mark White

Iodinize Oil,” JAMA, 67: 969-970. Coady, C. A. (1992). Testimony: A philosophical study. Oxford: Clarendon Press Craig, E. (1991). Knowledge and the state of nature: An essay in conceptual synthesis. Oxford:

Clarendon Press. Davis, M. E., & Fugo, N. W. (1950). Steroids in the treatment of early pregnancy complications.

Journal of the American Medical Association, 142(11), 778-785. Dieckmann, W. J., Davis, M. E., Rynkiewicz, L. M., & Pottinger, R. E. (1953). Does the

administration of diethylstilbestrol during pregnancy have therapeutic value?. American Journal of Obstetrics and Gynecology, 66(5), 1062.

Dutton, D. B. (1992). Worse than the disease: pitfalls of medical progress. Cambridge University Press.

Ferguson, J. H. (1953). Effect of stilbestrol on pregnancy compared to the effect of a placebo. American journal of obstetrics and gynecology, 65(3), 592-601.

Fisher, S., & Apfel, R. (1984). To do no harm: DES and the dilemmas of modern medicine. Fricker, M. (1998). Rational authority and social power: Towards a truly social epistemology.

Proceedings of the Aristotelian Society, 98, 159-177. Fricker, M. (2007). Epistemic injustice: Power and the ethics of knowing. Oxford University

Press. Fricker, M. (2010). Replies to Alcoff, Goldberg, and Hookway on epistemic injustice. Episteme,

7, 164-178. Gaffin, Ben, and Associates, American Medical Association, & Pharmaceutical Manufacturers

Association. (1958). Attitudes of US Physicians Toward the American Pharmaceutical Industry. The Author.

Gillam, R., & Bernstein, B. J. (1987). Doing harm: The DES tragedy and modern American medicine. The Public Historian, 9, 57-82.

Goldman, A. I. (2010). Why social epistemology is real epistemology. na. Greene, J. A. (2004). Attention to ‘details’: etiquette and the pharmaceutical salesman in postwar

American. Social Studies of Science, 34(2), 271-292. Greenhill, J. (1949). The 1949 Yearbook of Obstetrics and Gynecology. Chicago: Yearbook

Publishers.

Grim, P., Singer, D. J., Fisher, S., Bramson, A., Berger, W. J., Reade, C., ... & Sales, A. (2013). Scientific networks on data landscapes: question difficulty, epistemic success, and convergence. Episteme, 10, 441-464.

Hearings Before Senate Subcommittee on Antitrust and Monopoly (1961). Washington, D.C.: US Government Printing.

Heesen, R. (Forthcoming). Academic Superstars: Competent or Lucky? Synthese Heinonen, O. P. (1973). Diethylstilbestrol in pregnancy. Frequency of exposure and usage

patterns. Cancer, 31(3), 573-577. Holman, B. & and Bruner, J. (2015). The Problem of Intransigently Biased Agents, Philosophy

of Science, 82, 956-968. Holman, B & Bruner, J (Forthcoming). Experimentation by Industrial Selection, Philosophy of

Science Hong, Lu & Scott E. Page (2004). Groups of diverse problem solvers can outperform groups of

high-ability problem solvers. Proceedings of the National Academy of Sciences. 101, 16385-16389.

Hume, D (1739/2000). An enquiry concerning human understanding. Oxford University Press. IARC. International Agency for Research on Cancer. (2012) Diethylstilbestrol. A review of

human carcinogens. IARC Monograph Evaluation Carcinogenic Risks for Humans, 100, 175–218.

Jackson, Mathew. 2005. “A Survey of Models of Network Formation: Stability and Efficiency.” In Group Formation in Economics: Networks, Clubs and Coalitions, eds. Gabrielle Demange and Myrna Wooders, 11-57. Cambridge: Cambridge University Press.

JAMA (1949) JAMA, 139, 130. Kaufman, R. H. (1982). Structural changes of the genital tract associated with in utero exposure

to diethylstilbestrol. Obstetrics and gynecology annual, 11, 187. Kaufman, R. H., Adam, E., Hatch, E. E., Noller, K., Herbst, A. L., Palmer, J. R., & Hoover, R.

N. (2000). Continued follow-up of pregnancy outcomes in diethylstilbestrol-exposed offspring. Obstetrics & Gynecology, 96(4), 483-489.

Koppl, R. G., Kurzban, R., & Kobilinsky, L. (2008). Epistemics for forensics. Episteme, 5(02), 141-159.

Langston, Nancy. 2010. Toxic Bodies. New Haven: Yale University Press Lasagna, L. (1955). “Statistics, Sophistication, and Sacred Cows,” Clinical Research

Proceedings, 3, 185. Mayo-Wilson, C., Zollman, K., & Danks, D. (2013). Wisdom of crowds versus groupthink:

learning in groups and in isolation. International Journal of Game Theory, 42(3), 695-723.

McKinnon, R. (2016). Epistemic Injustice. Philosophy Compass, 11, 437-446. Meyers, Robert. 1983. DES: The Bitter Pill. New York: Seaview/Putnam. Podolsky, S. H. (2014). The antibiotic era: reform, resistance, and the pursuit of a rational

therapeutics. JHU Press. Reed, C. E., & Fenton, S. E. (2013). Exposure to diethylstilbestrol during sensitive life stages: a

legacy of heritable health effects. Birth Defects Research Part C: Embryo Today: Reviews, 99(2), 134-146.

Reid, D. D. (1955). The use of hormones in the management of pregnancy in diabetics. Lancet, 2, 833-836.

Robinson, D., & Shettles, L. B. (1952). The use of diethylstilbestrol in threatened abortion. American journal of obstetrics and gynecology, 63(6), 1330-1333.

Silverman, W. A. (1980). Retrolental fibroplasia: a modern parable. Saunders. Smith, O. (1948). Diethylstilbestrol in the prevention and treatment of complications of

pregnancy. American journal of obstetrics and gynecology, 56(5), 821-834. Strevens, M. (2003). The role of the priority rule in science. The Journal of philosophy, 100(2),

55-79. Swyer, G. I. M., & Law, R. G. (1954, January). An Evaluation of the ante-natal use of

Stilboestrol-preliminary report. Journal of Endocrinology, 10, vi-vii Troisi, R., Hatch, E. E., Titus‐Ernstoff, L., Hyer, M., Palmer, J. R., Robboy, S. J., ... & Hoover,

R. N. (2007). Cancer risk in women prenatally exposed to diethylstilbestrol. International journal of cancer, 121(2), 356-360.

Zollman, K. 2007. The Communication Structure of Epistemic Communities. Philosophy of Science 74: 574–87.

Zollman, K. 2010. The Epistemic Benefit of Transient Diversity. Erkenntnis 72: 17–35.