In this introductory chapter, I will first offer an overview of the two themes addressed in the present collection and their connection, then present the purpose and content of the volume. 1. DISAGREEMENT Disagreement is a pervasive feature of human life, not only because people constantly disagree with each other over almost any possible issue, but also because one tends to disagree with oneself over time. Although the mere existence of a disagreement does not by itself entail the impossibility of attaining knowledge or justified belief about the disputed matter, both personal experience and human history confirm that at least in many cases it is no easy task to find an effective way of settling controversies. Some disagreements are relevant from a merely theoretical perspective, but irrelevant from an ordinary viewpoint, not only because they do not arise in everyday life, but also because they have no bearing on our practical decisions. But there are also disputes with practical implications whose resolution depends on long, deep, and complicated theoretical discussions (e.g., disputes about abortion, euthanasia, torture, capital punishment, or drug legalization). The parties to such disputes engage in the practice of giving and asking for reasons with the aim of either convincing their rivals or else being convinced by them, an aim which most of the time is not achieved, and never achieved easily. It is of course possible to de facto settle disagreements of this kind even though one has not been able to determine which of the rival parties, if any, is rationally to be preferred over the others. This does not mean that the disagreement has been 'settled' properly speaking, but rather that one of the sides has in fact been chosen and that a given course of action will in fact be followed. This kind of 'resolution' may just be due to the pressure exerted by one of the contending parties on the basis of their influence or power. But it may also be due to the fact that one sometimes needs to arbitrarily choose a given course of action, even though one cannot justifiably affirm that it is the right one or even the most plausible one, for the Editor's Introduction Diego E. Machuca 1 2 Diego E. Machuca simple reason that one is dealing with urgent and vital matters. However, given what is at stake in some real-life situations, what one wants is to base one's decisions upon knowledge or justified belief. One wants to know or justifiably believe that one of the parties to a given dispute, if any, is right, because one thinks that the practical cost of error is high. Disagreement is thus of both epistemic and practical significance. From a philosophical perspective, one needs to explore the nature of both evidence and justification and the rules governing dialectical exchange. This would make it possible to develop effective ways of coping with disputes in general and of resolving those controversies which have a considerable bearing on everyday life. Classical epistemology has recently been criticized for being too individualistic, in that it assumes that cognitive achievements belong exclusively to the individual believer, thereby ignoring the crucial part that others play in the transmission and acquisition of knowledge or justified belief. This individualistic view is clearly not sufficient for a full appreciation of the epistemic significance of disagreement, since it does not take into account the impact that the opinions of one's dissenters may have upon one's beliefs. The narrow approach of traditional epistemology explains why there has been over the past few years an impressive progress in so-called social epistemology, which is the study of the social dimensions of knowledge and justification. Such progress is evidenced particularly in two areas, namely: the epistemology of trust-this includes the epistemology of testimony, which deals with trust in the testimony of others-and the epistemology of disagreement.1 Although research in these two areas has been conducted independently of each other, they are clearly connected. For in any recognized or acknowledged disagreement which is genuine, each disputant trusts the testimony of his rivals in the sense that each trusts that his rivals do believe what they claim to believe on the basis of what they take to be reliable evidence. In addition, whenever possible, one relies on the testimony of those whom one regards as experts in order to resolve a given controversy. Current research in the epistemology of disagreement has primarily focused on determining the properly rational attitude to adopt in the case of acknowledged2 disputes between epistemic peers,3 although some attention has also been given to acknowledged disputes involving epistemic superiors and inferiors.4 Discussion of peer disagreement has for the most part centered on two-person controversies, but some authors have also considered multiperson disputes-either between a person and a certain number of his like-minded peers or between groups of peers.5 What are epistemic peers or equals? Two individuals are deemed to be epistemic peers regarding a given question if and only if both are fully familiar with the relevant evidence and arguments, and are equal in their cognitive virtues or skills.6 An individual is an epistemic superior or inferior of another if and only if there is a difference with regard to either or both of those conditions. It should be noted that these definitions of epistemic peer and epistemic superior or inferior correspond to a highly abstract or idealized way of examining the epistemic Editor's Introduction 3 implications of disagreement, since they cannot be applied to real-life controversies. From a more realistic perspective, two persons are epistemic peers regarding a particular matter when they are acquainted with the available pertinent evidence and arguments to roughly the same extent, and possess similar cognitive virtues or skills. And a person is the epistemic superior or inferior of another when there is a considerable difference regarding either or both of those conditions.7 Two main views have been defended in discussions of peer disagreement, which are commonly labeled 'conciliationist' or 'conformist' and 'steadfast' or 'nonconformist'. As expected, each of these positions comprises variants. In what follows, I will offer a rough characterization of these two views and their most important versions, as well as of another view on disagreement which has recently been propounded in the literature. Conciliationism as a general position maintains that, in the face of revealed peer disagreement, all the parties to the dispute are rationally required to significantly revise their beliefs. That is, upon learning that a peer disagrees with me about whether p, I cannot rationally continue to believe that p or to hold it to the same degree or with the same confidence.8 The most prominent conciliationist view on peer disagreement is what Adam Elga has called the "Equal Weight View": Equal Weight View (EWV) It is rationally required to give equal weight to the opinions of all the parties to a peer dispute when there is no reason for preferring one opinion over the others which is independent of the very disagreement between the parties.9 This view can be interpreted in two different ways depending on whether one adopts a coarse-grained or a fine-grained approach to doxastic attitudes. On the former approach, one must suspend judgment with respect to p when one learns that a peer disagrees with one about this question, since there are only three possible attitudes that may be taken, namely: belief, disbelief, and suspension. On the latter approach, the disagreeing parties must split the difference in the degrees of confidence in their respective opinions. Within a Bayesian framework, the splitting-the-difference rule may lead to suspension when, e.g., the resulting credence falls outside what are considered the thresholds for belief and disbelief. It has been argued that it is preferable to interpret EWV in terms of the fine-grained approach because it makes it possible to apply the view to those disputes in which one of the parties suspends judgment about the contested matter. For what would be the middle term between disbelief and suspension?10 Given the widespread fear or dislike of skepticism among philosophers, the fine-grained approach has the additional advantage of weakening the connection between EWV and suspension of judgment. Note, in this regard, that one 4 Diego E. Machuca of the charges usually leveled against conciliationism more generally is that it ultimately leads to skepticism. I will have more to say about the connection between conciliationism and skepticism in the next section. The above formulation of EWV refers to a requirement, commonly called 'Independence,' which can be formulated as follows: Independence In order to resolve a peer disagreement over a given issue, the disputants must appeal to reasons which are independent of both their beliefs about the disputed issue and the reasoning on the basis of which such beliefs are formed.11 What conciliationists seek to avoid by this principle is any dogmatic or bootstrapping move by means of which anyone could dismiss out of hand his peer's dissenting opinion simply because it disagrees with his own, which is the correct one. Independence has been fiercely attacked by nonconciliationists, who claim that at least in many cases one's peer's disagreement over the question whether p shows that he has not rationally or reasonably responded to the relevant first-order evidence. This is so when, e.g., my peer disagrees with me about whether 12 x 5 = 60 or about whether there is a person sitting two feet in front of us or about whether a restaurant we have been visiting for the last ten years is on a given street. In each of these cases, it is argued, I begin with an extremely high level of rational confidence in the truth of my belief and the reliability of my faculties, and it is therefore absolutely clear that my peer is suffering from some kind cognitive malfunctioning or else being insincere-he may just be lying or pulling my leg. My first-person perspective grants me access to information about my reasons and cognitive states which I lack about my rival's.12 One may retort, however, that such cases can be accounted for without appealing to the belief about the disputed issue or the reasoning behind it, but to more general considerations. For it could be argued that, since it is highly unlikely that two people thinking lucidly about the kinds of simple issues in question hold rival opinions, the most probable explanation of their disagreement is that one of them is confused, disingenuous, or cognitively deficient (see Christensen 2009a, 2011). Another key thesis endorsed by at least the great majority of conciliationists is the so-called Uniqueness Thesis: Uniqueness Thesis (UT) The total body of available evidence E bearing upon proposition p epistemically justifies only one doxastic attitude towards p or one degree of confidence in p.13 What this thesis claims is that, on the basis of E, one should believe, disbelieve, or suspend judgment about p. Or if one prefers a fine-grained approach Editor's Introduction 5 to doxastic attitudes, then E justifies only one degree of confidence in p ranging from 0 to 1. Thus, given E, there is a unique doxastic attitude towards p which it is rational to take, or a unique level of credence in p which it is rational to possess. It seems plain why this thesis is endorsed by conciliationists. For, if in the face of peer disagreement one is rationally required to significantly diminish one's confidence in one's belief about the disputed matter, it is because at most one of the beliefs held by the disputants, or some other belief they could hold, can be right. Otherwise, if mutually incompatible beliefs about the same matter are epistemically justified by the same evidence and the disputants are therefore fully rational in their beliefs, then there would be no need for them to revise these beliefs. Richard Feldman (2007: 204–5) explicitly claims that rejecting UT implies accepting that there can be reasonable disagreements, which is precisely what conciliationists deny. Some critics of conciliationism (proponents of EWV in particular) have argued that it is indissolubly linked with UT in the sense that commitment to the former implies commitment to the latter, and that given that UT is an extremely implausible or unobvious claim, its strong connection with conciliationism is fatal to this view (e.g., Kelly 2010: 119–21).14 Those who reject UT adopt some kind of epistemic permissiveness, which might be formulated thus: Permissiveness The total body available evidence E bearing upon proposition p is compatible with different doxastic attitudes towards p or with different degrees of confidence in p.15 It is worth noting that the above formulation of UT rules out the possibility of there being a degree of belief which, albeit not maximally or perfectly rational, is still rationally permissible. David Enoch (2010: 957 n.9) has claimed that the discussion of UT and of epistemic permissiveness in the literature is misleading insofar as UT states that there is a unique degree of belief which is maximally rational. This thesis can therefore be denied by asserting that no one degree of belief is maximally rational, which leaves open the possibility of there being other rationally permissible degrees of belief. Although this way of construing UT is certainly possible, it is not necessary and, to the best of my knowledge, it is not the way in which its proponents interpret it. Conciliationism is rejected by those who adopt steadfast or uncompromising views on peer disagreement. According to these views, in at least quite a number of cases it is perfectly rational or reasonable to retain one's belief in the face of a dispute with someone whom in general one regards as an epistemic equal.16 There are two main nonconciliationist positions. Some claim that in certain cases one can legitimately ignore one's peer's belief about the disputed matter and retain one's own with unaltered degree of confidence. Others affirm that, although one is always required to give some 6 Diego E. Machuca weight to one's peer's belief, in some cases one can retain one's belief with a degree of confidence which is close to one's initial degree of confidence. Each of these views, in turn, may be further subdivided depending on whether or not one accepts epistemic permissiveness. Thus, those who take up the first view may claim either that only one of the disputants can dismiss his peer's opinion and retain his own with the same level of confidence or that both disputants can do so. For their part, those who take up the second view may contend either that only one of the disputants can retain his opinion with a slightly diminished level of confidence or that both can do so.17 It may be argued that acceptance or rejection of epistemic permissiveness is not the only basis for this distinction. For the question of the reasonableness or rationality of peer disagreement may be couched either in terms of which of the contending positions is in fact warranted by the evidence or rather in terms of whether from a first-person perspective each of the disputants has valid reasons for preferring his own position over his rival's.18 Being reasonable or rational in one sense does not entail being reasonable or rational in the other, so even if one rejects epistemic permissiveness, there may still be a sense in which all disputants can be reasonable or rational in sticking to their guns. Accordingly, acceptance or rejection of UT is relevant to the question of the reasonableness or rationality of peer disagreement only if this question is tackled in terms of which of the rival views is in fact best supported by the evidence bearing on the disputed issue. What all steadfast views have in common is their rejection of Independence, since they maintain that a person can prefer his own position over that of his rival by appealing to the very disagreement between them. That is, one can demote or downgrade one's opponent without having recourse to reasons which are independent of either one's belief about the disputed matter or the reasoning supporting this belief. As observed above, conciliationism and steadfastness are the two main views adopted in the literature. But there are other notable alternatives which have recently been propounded, in particular Jennifer Lackey's "justificationist" account of the epistemic importance of disagreement (Lackey 2010a, 2010b), which is in some respects very similar to the view advocated by Ernest Sosa (2010). Lackey rejects both conformism and nonconformism on the basis that each can adequately account for only some of the cases of epistemically relevant controversies. This shows, in her view, that the thesis of uniformity, endorsed by both conformists and nonconformists, should be rejected: Uniformity Disagreement with epistemic peers functions the same epistemically in all circumstances. (Lackey 2010a: 302) Thus, according to this view, controversies between epistemic peers in any area or about any topic present the same epistemological problem, and hence the way of dealing with them should be the same. That is, if, in the Editor's Introduction 7 face of peer disagreement, one thinks that doxastic revision is necessary or instead that one can retain one's belief, then one should adopt such an attitude across the board. What Lackey's justificationist view maintains is that one can retain one's belief in the face of ordinary peer disagreement when one's personal information-i.e., information about the functioning of our own cognitive capacities-provides one with a high degree of epistemically justified confidence in one's belief. If one knows that one finds oneself in optimal epistemic conditions, then the probability of one's belief being false is extremely low. Thus, the reason why in some disputes steadfastness is the correct response is that one's degree of justified confidence in one's belief is high, and the reason why in other disputes conciliationism is the correct response is that one's degree of justified confidence in one's belief is low.19 Let me note that it actually does not seem to be the case that all (or even most) conformists and nonconformists endorse Uniformity. Sosa (2010), for instance, does not think that controversies regarding certain perceptual experiences or certain mathematical calculations are on a par with controversies about political and moral matters. Moreover, despite the differences between the two main positions on peer disagreement, some proponents of both positions agree that there is no general answer to the question how one should rationally respond to that kind of disagreement.20 For one must take into account the epistemically relevant characteristics of each particular dispute, such as the comparative weight of the first-order and the higher-order evidence and the background beliefs of the disputants. Of course, the answer will also vary depending on whether the controversy is examined from the perspective of the disputants or from that of a third-party onlooker. 2. SKEPTICISM Another topic of lively discussion in contemporary epistemology is skepticism, particularly so-called Cartesian skepticism, but also Pyrrhonism, the former consisting in the denial of the possibility of knowledge in general or in a specific area, and the latter consisting in global suspension of judgment about the possibility of knowledge and justified belief. There is clearly a close connection between skepticism and disagreement, since skepticism is always latent as a possible stance to adopt in any discussion of disagreement. For instance, on the dialectical conception of justification, the very existence of a dispute triggers a demand for justification: a competent and responsible cognizer should be able to defend his beliefs when these are challenged by his epistemic rivals. There is a crucial difference within those who adopt this conception of justification: whereas dialectical foundationalists affirm that only some disagreements pose a challenge that needs to be met, dialectical egalitarians maintain that any disagreement poses such a challenge.21 But for present purposes the important point is that, if such dialectical defenses do not yield definite and agreed upon answers in favor of any one of the parties 8 Diego E. Machuca to a given dispute, then one may conclude either that justified belief about the topic in question is impossible or that it is necessary to suspend judgment about which of the competing beliefs, if any, is justified. Even if one rejects the dialectical conception of justification, disagreement still poses a skeptical threat in case one adopts a no-defeaters condition on justification. For the very existence of a dispute about a given issue can be taken to yield a full or partial defeater for the justification of each disputant's belief. If none of the parties can provide a defeater-defeater, then one must either deny that the competing beliefs are (fully) justified or suspend judgment about which of them, if any, is (fully) justified. As we saw in the previous section, agnostic skepticism is the skeptical stance considered in current epistemological discussions of disagreement, where the question is posed whether the right attitude to adopt in the face of peer dispute is suspension of judgment or, at the very least, significant belief revision. Conciliationists give an affirmative answer, but it is a mistake to think that their views necessarily entail widespread skepticism, much less global skepticism. The reason is that one can infer skepticism only if the antecedents of the conciliationist epistemic principles are satisfied, something which their proponents do not think happens always or most of the time. To make this clear, it will be useful to briefly consider the views of the most prominent supporters of conciliationism. David Christensen (2007, 2011) maintains that epistemic peers must split the difference in the degrees of confidence in their respective beliefs, and so his view does not entail that one is required to suspend judgment in each case of peer disagreement. In addition, peer disagreement is unequally distributed: whereas many moral, religious, political, and philosophical beliefs are subject to significant peer dispute, most mathematical, scientific, and everyday beliefs are not. Although Adam Elga (2007) frames the discussion in terms of degrees of credence, he claims that EWV requires suspension of judgment. However, cases of peer dispute are rare, and so the suspension of judgment in question is restricted to very specific circumstances. For his part, Richard Feldman (2005, 2006, 2007) adopts an all-or-nothing conception of belief, and hence claims that one is rationally required to suspend judgment in the face of peer dispute. He is one of the few conciliationists to characterize his view as skeptical, albeit in a limited sense, since peer disagreement-and hence suspension of judgment-does not extend across the board but rather covers a significant number of cases. For instance, unlike full-fledged skeptics, Feldman maintains that, if one's rival disagrees with the claim that astrological beliefs are false or that cruelty is not to be prized, then it is plain that he is unreasonable (2006: 230; 2007: 211–12). In sum, the connection between conciliationism and skepticism is much weaker than usually thought. Conciliationists argue either that discovery of peer disagreement does not always mandate suspension of judgment; or that, even if it does, this kind of dispute is infrequent; or that, despite being a common phenomenon, peer disagreement does not extend across the board. In addition, since the current discussion of the epistemic Editor's Introduction 9 significance of disagreement focuses almost exclusively on peer dispute, even the most widespread skepticism entailed by conciliationism will be limited in scope, leaving intact large bodies of our beliefs. Thus, the type of agnostic skepticism found in the literature on disagreement has little to do with the radical agnostic skepticism adopted by the ancient Pyrrhonian skeptics, who suspended judgment across the board on the basis of arguments applicable to any kind of disagreement. When reading the current epistemological literature on disagreement, some may come to think that the skeptical problems posed by the existence of controversies have only now started to be taken into careful consideration. But this is inaccurate for at least the following four reasons. First, the epistemic and practical implications of disagreement were a central focus of discussion in the ancient Pyrrhonian tradition. The argument from disagreement was one of the Five Modes of Agrippa and underlay the Ten Modes of Aenesidemus. This is why the connection between disagreement and skepticism in its agnostic form has been examined in the literature on ancient Pyrrhonism.22 In relation to this first reason, let me note the curious fact that those contemporary epistemologists who have carefully analyzed the challenges posed by the Agrippan modes have focused almost exclusively on the three modes which constitute the so-called Agrippa's Trilemma- infinite regress, reciprocity, and hypothesis-paying little or no attention to the mode from disagreement.23 Conversely, in the growing literature on the epistemology of disagreement there is no discussion of the trilemma. This is certainly regrettable because there is much to learn from the two lines of inquiry; in fact, the trilemma and the mode from disagreement were normally used by Pyrrhonian skeptics as part of the same argumentative strategy. It is likewise unfortunate that, just as most specialists on ancient Pyrrhonism are unaware of the great deal of attention that the problem of disagreement has recently attracted from contemporary epistemologists, so too do most of the latter ignore the Pyrrhonian discussion of the skeptical implications of pervasive controversies. This is something regrettable because ancient philosophy scholars interested in the Pyrrhonian treatment of disagreement could profit from the depth and sophistication attained in the current disagreement literature, whereas contemporary analytic philosophers could get familiarized with a unique and intriguing skeptical stance. As already noted, in the modernday philosophical scene, the variety of skepticism commonly addressed is that which denies the possibility of knowledge in general or in a particular domain and which is based on arguments which are purely theoretical or at least quite remote from real-life concerns. The variety of skepticism consisting in suspending judgment in the light of certain kinds of disagreement we all face in our lives is sometimes wrongly taken as some sort of philosophical novelty due to the lack of knowledge of Pyrrhonian skepticism. Second, modern philosophers were much concerned with the skeptical implications of disagreement. This was due in part to the rediscovery of Sextus Empiricus' Pyrrhonian works in the Renaissance. The most prominent 10 Diego E. Machuca example is probably Montaigne, who in his Essays constantly appeals to philosophical, religious, and scientific controversies to argue that humans are unable to know the truth by themselves. In the Rules for the Direction of the Mind and in the Discourse on the Method, Descartes takes diversity of opinions as an indication that the disputants lack knowledge or that their views are false. In the Enquiry, Hume maintains that the competing miracle claims of the world's religions cancel each other out, which is a reason for rejecting belief in miracles. In the Critique of Pure Reason, Kant appeals to dispute and opposition to motivate skeptical arguments. Third, the skeptical implications of disagreement have since long been much debated in contemporary metaethics, where specialists have examined whether the very existence of unresolved moral disputes shows that there are no objective moral values, properties, or facts. The most prominent example of the use of disagreement to undermine ethical realism is no doubt John Mackie, who based his "moral error theory" on two arguments: the argument from queerness and the argument from relativity, which is actually an argument from disagreement. Ethical skeptics usually conceive of this argument as an inference to the best explanation: they claim that the best explanation of the existence of persistent and widespread disputes about moral issues is that moral beliefs do not reflect an objective moral reality, but merely the perspectives of those holding such beliefs.24 Some authors have also recently examined whether the argument from moral disagreement shows that knowledge about controversial moral matters is not possible.25 Finally, philosophers of religion have for some time now explored whether religious disagreement calls into question or undermines the epistemic justification or the rationality of religious belief. The discussion of the challenges posed by religious diversity has been conducted particularly within the framework of the debate between religious pluralism, religious exclusivism, and religious skepticism. Whereas the religious pluralist claims that the phenomenon of religious diversity shows that all religions are epistemically on a par, the religious exclusivist maintains that it is rational to believe that one's own religion is the true one whereas all others are either false or considerably deviate from the truth. However, they both agree on the existence of a supernatural entity to which we can have some sort of cognitive access, whereas the religious skeptic holds that awareness of religious diversity makes it rationally required to suspend judgment about both the existence and the knowability of such an entity.26 It is worth noting that the early papers on the epistemology of disagreement mention or discuss some of the purely epistemological views found in the literature on religious diversity. Before presenting the aim and content of the present volume, let me note that, in relation to the other main area of social epistemology, exploring the epistemic significance of disagreement and its connection with skepticism makes more pressing the examination of the reliability of the testimony of both our epistemic peers and our epistemic superiors and, hence, of whether we should trust them. Indeed, in order for disagreement with a person whom Editor's Introduction 11 we consider to be a peer to be epistemically relevant, we have to trust that his evaluation of the first-order evidence bearing on the disputed matter does support for him a view genuinely different from ours. And when we defer to the opinion of a person whom we regard as an expert or epistemic superior in order to settle a given controversy, we have to trust that he is being honest when expressing his views on the matter at hand. A radical skeptic would raise the question whether the evidential basis for our trust in others is ever sufficient to make our trust in the testimony of our epistemic peers and superiors epistemically justified or well-grounded. Although of considerable import, treatment of this issue will not be carried out in the present collection, and will have to wait for another occasion. 3. THE PRESENT VOLUME We have seen that the relationship between disagreement and skepticism is a focus of analysis in the burgeoning area of epistemology concerned with the significance of disagreement. Still, the relationship has arguably not received the full attention it deserves. For there has been no systematic and thorough exploration of the skeptical implications of disagreement, part of the reason being that any robust and genuine form of skepticism is regarded by at least many philosophers as an absurd, untenable, or incoherent stance which cannot be considered a real option. Such a dismissive view is surprising because it seems to be based not only on a lack of recognition of the sophistication and subtlety of the arguments for radical skepticism, but also on ignorance of the undeniably crucial role that the distinct skeptical traditions have played in the history of philosophy since antiquity. Although the low regard in which skepticism is held is in no way exclusive to epistemology, in other areas of philosophical inquiry it has not prevented researchers from examining in depth the connection between disagreement and skepticism. The present volume proposes to explore in detail the possible skeptical implications of disagreement in different areas and from different perspectives, with an emphasis on the current debate over the epistemic impact of disagreement. Although other volumes have recently been devoted to the philosophical significance of disagreement,27 their main theme is not the connection between skepticism and dispute, and few of their contributions touch upon this link. The thirteen new essays collected here deal essentially with four issues: (i) the Pyrrhonian approach to disagreement and its relevance to the current epistemological discussions of the topic, (ii) the relationship between disagreement and moral realism and antirealism, (iii) disagreement-based skeptical arguments in contemporary epistemology, and (iv) disagreement and the possibility of philosophical knowledge or justified belief. As for the contributors, the guiding idea was to include essays by both senior and younger scholars who have consistently been working on either or both of the themes of the volume. 12 Diego E. Machuca The first five essays explore the skeptical implications of disagreement in areas in which such implications have been a central focus of attention, namely, Pyrrhonian skepticism and metaethics. There follow six essays which examine the significance of disagreement exclusively from the perspective of contemporary epistemology. The final two essays look at the challenges that persistent dispute poses for philosophical inquiry in general. Otávio Bueno takes issue with some points of Jonathan Barnes' influential interpretation of the Agrippan mode from disagreement. Two of these points are the claim that this mode cannot induce suspension of judgment by itself, but needs to interact with the three modes that form Agrippa's trilemma; and the claim that, by suspending judgment, the Pyrrhonist becomes a part of the disagreement. With respect to the first point, Bueno argues that Thomas Kelly's Total Evidence View, according to which the correct response to a peer disagreement is determined by the total body of available evidence bearing on the disputed matter, may provide a sufficient condition for inducing suspension on the basis of disagreement alone. For, if one comes to the conclusion that the total available evidence does not favor any of the disagreeing parties, then suspension is the natural outcome. As for the second point, Bueno contends that most disagreements are not disagreements in attitude, but positive disagreements, i.e., disputes between incompatible answers or solutions to a given question. If so, then the Pyrrhonist is not a part of the disagreement precisely because, in suspending judgment, he makes no claim about the correct answer or solution to the question under dispute, but expresses his inability to provide such an answer or solution. As noted above, contemporary epistemological discussions of disagreement have not in general recognized the full extent of its connection with skepticism. Markus Lammenranta's essay sheds light on at least one of the reasons for this. Arguing that disagreement plays a key role not only in the Pyrrhonian but also in the Cartesian skeptical arguments, he contends that these arguments are intuitively sound and that their intuitiveness cannot be accounted for unless we assume a dialectical conception of justification. As we saw, this view maintains that one is justified in holding a belief if and only if, when appropriately challenged, one is able to defend it by offering reasons for it. Lammenranta claims that such a conception of justification should be accepted because it is rooted in our ordinary epistemic practices, and that most epistemologists fail to appreciate and explain the strength of disagreement-based skeptical arguments because of their adoption of an individualistic and nondialectical epistemology. My chapter approaches the current epistemological debate on peer disagreement from a neo-Pyrrhonian perspective, thus adopting a form of skepticism which is more radical than those discussed in the literature. It makes use of argumentative strategies found in ancient Pyrrhonism both to show that such a debate rests on problematic assumptions and to block some maneuvers intended to offer an efficacious way of settling a considerable number of peer disputes. The chapter takes issue with three views held in Editor's Introduction 13 the peer disagreement debate: there is an objective fact of the matter about at least most controversial questions; we possess theory-neutral evidence bearing on those questions which grants us access to the truth of the matter; and many peer controversies are resolved by attending to which disputant has correctly evaluated the objective evidence. With respect to the first two views, it is argued that the belief in both objective facts and theory-neutral evidence is subject to fierce dispute, and should not therefore be taken for granted in the discussion of peer disagreement. As for the third view, it is argued that from either a firstor a third-person perspective, there seems to be epistemic symmetry between the disputants which makes it necessary to suspend judgment. As already observed, the question whether skepticism is the proper response to moral disagreement has long been one of the key topics of debate in metaethics. Accordingly, two essays have been included which provide fresh insights on the connection between moral disagreement and skepticism. In the first of them, Folke Tersman explores both whether merely possible moral disagreement is as epistemically threatening as actual moral disagreement and whether skeptical arguments based on the possibility of moral disagreement necessarily lead to global skepticism. In relation to the first question, he maintains that there are skeptical arguments which allow one to draw an antirealist conclusion on the basis of actual moral disagreement but not on the basis of merely possible moral disagreement. For instance, only a skeptical argument that appeals to the actual existence of radical moral disputes-i.e., moral disputes between individuals with no discernible cognitive shortcomings-can undermine the pro-realist argument which affirms the actual existence of moral consensus and claims that moral realism is the best explanation of such a consensus. In connection to the second question, Tersman argues that, whereas one can construct an argument for moral antirealism on the basis of the possibility of radical disagreement, this type of argument is not viable in those areas in which disagreements are clearly explained by some sort of cognitive flaw. Although the analysis is mainly focused on disagreement in morality, the essay also takes account of the current epistemological debate on peer dispute. Curiously enough, whereas many moral skeptics have claimed that the existence of moral disagreement calls into question the possibility of moral truth and knowledge, some moral realists have contended that its very existence implies that the disagreeing parties are committed to such a possibility. In his contribution, Zed Adams critically engages with this debate. He claims that both sides have been insufficiently interested in identifying the peculiar features of moral disagreement, an oversight which has led them to adopt distorted accounts of the nature of moral thought. Disagreementbased skeptical arguments have underestimated the widespread and persistent character of moral dispute, which has led them to mischaracterize the role reason-giving plays in moral debate. Disagreement-based realist arguments have overlooked the variety of forms which disagreement can take, 14 Diego E. Machuca which has led them to neglect the possibility that certain moral disputes might turn out not to concern genuinely truth-evaluable questions. The moral that Adams draws from these oversights is that neither skeptical nor realist views about the nature of moral thought are adequately equipped to acknowledge the fragile basis of moral disagreement. It is often argued that, whereas conciliationism ultimately leads to skepticism, nonconciliationism ultimately leads to dogmatism. Since both skepticism and dogmatism are considered to be unacceptable or objectionable, their respective intimate connections to conciliationism and nonconciliationism are regarded as fatal to these views. The next two essays of the volume examine whether these connections actually hold. In their contribution, Brandon Carey and Jonathan Matheson explore the ways in which EWV may result in skepticism. After offering a detailed characterization of EWV, they discuss and reject two standard arguments to the effect that this view entails that one's awareness of either an actual or a merely possible disagreement with an epistemic peer or superior requires one to suspend judgment about the contested issue. The possible-disagreement-based argument is unsound because awareness of merely possible disagreement does not have the same epistemic impact as awareness of actual disagreement. The actual-disagreement-based argument is unsound because it disregards the fact that most disagreements are not two-person disputes, but involve more people (including other peers and superiors) whose opinions are hardly ever symmetrically distributed. If one's peers or superiors tend to agree with one on the disputed matter, then this fact constitutes a reason to discount the opinion of one's dissenting peer or superior which is-as EWV requires-independent of one's disagreement with him. The authors nonetheless claim that we have insufficient information about both the exact distribution of opinions in a great many instances of disagreement and the precise weight that should be given to each of these opinions. Such ignorance together with our reasons to doubt that the distribution of opinions is an accurate indicator of what the first-order evidence in fact supports lead to suspension of judgment about an important number of controversial issues. Thus, EWV does have significant skeptical implications. For his part, Duncan Pritchard argues that not all forms of nonconciliationism or nonconformism are dogmatic. He distinguishes between strong nonconformism-according to which in the face of peer dispute one can retain one's belief with the same degree of confidence-and moderate nonconformism-according to which one can do so only if, upon reflection, one comes to the conclusion that the epistemic basis for one's belief is sound. Only moderate nonconformists can construct track-record arguments (all of which are inductive in nature) that establish without circularity or bootstrapping, and hence without failing into dogmatism, that one is epistemically superior to one's presumed epistemic peer. For the premises of such arguments are representative samples insofar as careful reflection shows that the epistemic basis for each premise is solid. Pritchard further argues that the Editor's Introduction 15 nonconformist's strategy is successful against the local skeptical challenge posed by peer disagreement, but not against the much more radical skeptical challenge posed by disagreement between incommensurable worldviews. Clayton Littlejohn's essay offers a qualified defense of EWV and the skeptical argument based upon it. Although he finds the view quite plausible, he abstains from endorsing it. This is why his aim is not to prove that EWV is correct, but to show both that there is an intuitively compelling argument for it and that two arguments recently advanced against it are unsuccessful. The argument for EWV is based on an analogy: just as one should suspend judgment when two instruments disagree and there is no reason for thinking that one of them is more reliable than the other, so too should one suspend judgment when involved in a disagreement with an epistemic peer. The arguments against EWV intend to establish that it is self-defeating, and that adopting a first-person perspective undermines the agent-neutral epistemic norm on which it is based. The reason why EWV is not self-defeating is that it does not claim that one should believe it no matter what the evidence indicates about its correctness, but only implies that one should believe it provided the evidence supports it. And the egoist argument fails because it is not justified to claim that one can have greater confidence in one's views than in one's peer simply because they are one's own. Nathan King argues that disagreement-based skepticism cannot successfully use the conciliationist principles we are familiar with as premises in an argument for wide-ranging suspension of judgment. One reason for this is that those principles appeal either to the notion of epistemic peerhood or to that of epistemic symmetry, notions that may be applicable in the case of idealized disagreements, but not in the case of actual or real-life disputes. One might think that, given the widespread and deep feeling of uneasiness about skepticism among philosophers, King's conclusion will be most welcome by the majority of conciliationists: their view does not after all lead to skepticism. However, this welcome news will quickly wear out its welcome. For King argues that disagreement-based skeptical arguments applying the most commonly defended conciliationist principles fail for a second reason: the principles themselves are questionable. Still, he leaves open the possibility that there may be other epistemic principles that could be effectively used in an argument from disagreement that seeks to induce wide-ranging suspension of judgment. Trent Dougherty takes issue with skeptical arguments from peer disagreement, arguing that reasonable dispute is consistent with epistemic peerhood. Approaching the question through the lens of Richard Jeffrey's type of probabilism, he maintains that controversies between epistemic peers can sometimes be settled by relying on one's own perspective. The reason is not that one should prefer one's own position just because it is one's own, but that introspection as a source of evidence concerning one's own mental states normally provides stronger epistemic support than does testimony as a source of evidence concerning other people's mental states. Still, even 16 Diego E. Machuca though one can rationally retain one's belief in the face of peer dispute, one cannot do so with the same strength as prior to knowing about one's peer's disagreement. Dougherty also claims that special principles devised to handle controversies between epistemic equals create more confusion than clarity and are unnecessary insofar as such controversies can be dealt with by calculating the probability that one's belief is true given one's total evidence. Nathan Ballantyne's essay is concerned with what he calls "the problem of historical variability," which stems from the idea that people's beliefs about controversial matters vary in relation to, and hence are dependent upon, their different backgrounds. Although some authors have inferred therefrom that our disputed beliefs are arbitrary and should therefore be abandoned, they have not offered arguments in favor of this skeptical conclusion or even explained what exactly the problem is. This is why, after identifying what is worrisome about historical variability, Ballantyne constructs two arguments for the conclusion that beliefs about contentious issues are irrational. Whereas the first works by combining the historical variability thesis with a claim about the epistemic symmetry of the disagreeing parties, the second works by combining it with a claim about (a certain kind of) causal arbitrariness. These arguments differ from peer-disagreement-based arguments both in that they appeal to possible disagreements and in that they do not concern disputes between two different persons but between a person and his counterfactual self. Ballantyne is careful to note that, if his arguments are successful, the type of skepticism they induce is local, since it is restricted to those beliefs which are subject to dispute. As noted at the outset, disagreement is a common phenomenon of human life. However, there are certain areas in which it is particularly fierce, such as morality, politics, religion, and philosophy. The case of philosophy deserves special consideration. Anyone with a background in this discipline knows how much philosophers disagree with one another about nearly any of the subjects they happen to be investigating. This can be observed in present-day philosophical discussions, but the fact becomes much more salient when one turns to the history of philosophy: one sees that philosophers of all times have systematically disagreed with both their contemporaries and their predecessors. Such controversies have taken place even (and sometimes especially) within the same philosophical school, tradition, or movement. What renders philosophical dispute especially problematic is the fact that the persistence of disagreement cannot simply be explained by appealing to the foolishness, narrow-mindedness, ignorance, confusion, or lack of insight of one or more of the disputants. Of course, many of us suffer from one or more of these flaws, but even in the case of the best philosophical minds agreement is extremely hard to find. What can then be expected from philosophy when its practitioners are not able to come to agreed upon solutions to longstanding problems, despite devoting their lives to reflecting on them, being acquainted with the relevant evidence, knowing and understanding the rival arguments bearing on the disputed issues, and being competent, responsible, Editor's Introduction 17 and honest cognizers? Such continuous failure is the reason for the wellknown claim that there is no progress in philosophy-which should actually be qualified by saying that there is no substantial advancement in most areas of philosophical research, logic being one of the very few exceptions. This raises questions such as: What are we really doing when we do philosophy? What is the aim of philosophical investigation? And what can we reasonably expect to achieve? Some excellent work has recently been done on the difficulties posed for philosophical inquiry by widespread and deep-rooted disagreements,28 and the final two essays aim to further advance the debate. They have been chosen to conclude the volume because the problem they address can be observed in the philosophical disagreements between the other contributors. Hilary Kornblith claims that the situation of philosophical investigation is deeply problematic because the entrenched unresolved disagreements between "experts" entail that there is no philosophical progress and no philosophical knowledge, contrary to what paradigmatically occurs in the sciences. Indeed, whereas in the latter dispute tends to be settled over time and there is convergence to the truth, no such thing happens in philosophy. In the case of the sciences, both the layman and the specialist should defer to the opinion shared by the majority of experts, because it will most likely be correct. In philosophy, by contrast, this is not possible because in most areas there is no agreement among a majority of experts, and when there is no such agreement, the only rational attitude to adopt is suspension of judgment. Moreover, it is not even clear that in philosophy there are experts understood, not as socially recognized individuals, but as people who are well-placed to discover the truth about certain issues. Kornblith also addresses the objection according to which his view is self-refuting or self-undermining, which leads him to a sort of aporia: even though he cannot offer a satisfactory response to the charge, he believes that there is nothing wrong with the premises of his argument and that its conclusion validly follows from them. Like Kornblith, Sanford Goldberg espouses a form of skepticism about philosophy. He claims that some philosophical controversies are systematic peer disagreements, by which he means that they are nonlocal, widespread, and entrenched disputes between epistemic equals. Taking for granted that the systematic character of those philosophical controversies makes it unreasonable to think that there is knowledge or justified belief about the disputed philosophical matters in question, his purpose is to determine whether this skeptical stance undermines the viability of standard philosophical practice. More precisely, does such skepticism entail that one should not have views on controversial philosophical issues, that one should not make claims about those issues, and that one would be insincere were one to make such claims? Goldberg maintains that none of these consequences follows. First, holding a view only requires that one regard it as defensible and commit oneself to defending it, something one can do even when acknowledging 18 Diego E. Machuca that one's reasons do not justify outright belief in it. Second, in the context of acknowledged systematic philosophical disagreement, one's claims about controversial philosophical issues are warranted provided they are defended when challenged, even though they do not conform to a norm of justified belief. Finally, in such a context, none of the parties to a philosophical debate expects that their opponents believe the views they are defending, but only that they regard these views as worthy of defense. As a result, none should accuse the others of insincerity for not believing their own views.29 NOTES 1. On the epistemology of trust in general, see Foley (2001) and Faulkner (2011). On the epistemology of testimony more specifically, see Coady (1992), Goldberg (2007, 2010), Lackey (2006, 2008), and Lackey & Sosa (2006). For a recent treatment of both trust and testimony, see McMyler (2011). For an overview of the epistemology of disagreement, see Christensen (2009a), Lackey (2010c), Thune (2010), and Frances (2011). For a cross section of the research currently conducted in social epistemology, see the essays collected in Haddock, Millar, & Pritchard (2010). 2. Henceforth, whenever I talk of 'peer disagreement', I mean peer disagreements which are recognized or acknowledged as such by the rival parties. 3. The now technical expression 'epistemic peer' was first used by Gutting (1982). 4. On disputes involving epistemic superiors and inferiors, see especially Frances (2010, 2011, 2012, 2013); also Carey and Matheson's chapter in this volume (chapter 7). 5. See, e.g., Conee (2009), Frances (2010, 2012), and Lackey (2010b). 6. Adam Elga offers a different definition of 'epistemic peer'. In his view, I can count a person as my epistemic equal with respect to the question whether p if and only if I think that, conditional on a disagreement about p arising, the two of us are equally likely to be mistaken. The reason for preferring this definition is that I can think that my rival, despite being clever, well-informed, and thorough, is more likely than I to be mistaken (2007: 487, 499 n.21). One might object that my assessment of such likelihood actually depends on my assessment of my and my rival's familiarity with the pertinent evidence and arguments, and of our intellectual virtues and skills. If so, then Elga's view is not different from the standard one. I assume this is the reason why, although Christensen adopts the standard definition of 'epistemic peer' (2007: 188–89, 192, 211), he occasionally casts the discussion in terms of whether the disagreeing parties are equally likely to be mistaken about the disputed issue (2007: 196–200, 203–4). 7. For the distinction between real-life and idealized disagreements, see Lackey (2010a: 303–5), King (2012), and King's chapter in this volume (chap ter 10). 8. The main proponents of conciliationism are Feldman (2003, 2005, 2006, 2007, 2009), Christensen (2007, 2011), and Elga (2007, 2010). Other conciliationists include Matheson (2009) and Kornblith (2010). 9. For Elga's own formulation of EWV, see Elga (2007: 490). This view is already found in Sidgwick (1895: 152–53, 1905: 464); cf. Sidgwick (1874: 321). Although at one point Christensen seems to endorse EWV (2007: 193), most of the time he adopts the more mitigated conciliationist stance according to which, in the face of peer dispute, one should significantly reduce one's confidence in one's belief about the contested issue (2007: 189, 203, 212). Editor's Introduction 19 10. See Kelly (2010: 117–18); cf. Sosa (2010: 279 n.3). 11. Similar versions of this principle are explicitly endorsed by Christensen (2007), Elga (2007), and Kornblith (2010). 12. For arguments against Independence, see, e.g., Enoch (2010), Lackey (2010a, 2010b), Sosa (2010), and Kelly (2013). This principle is also critically examined in Nathan King's chapter in this volume (chapter 10). 13. The expression "Uniqueness Thesis" is Feldman's (2007). Christensen (2007) speaks of "Rational Uniqueness." Proponents of UT include Christensen (2007), Feldman (2007), and Matheson (2011). Detractors include Douven (2009), Conee (2010), and Ballantyne & Coffman (2011). Strong doubts about the truth of UT are also voiced by Kelly (2010: 120–21). 14. Ballantyne & Coffman (forthcoming) agree with Kelly in criticizing conciliationism, but claim that this view does not necessarily commit one to UT because there is also a permissive form of conciliationism. In this regard, note that Christensen (2007: 211; 2009a: 763–64) already argues that some permissive accounts of rational belief are compatible with conciliationism. 15. For a detailed criticism of epistemic permissiveness, see White (2005), who nonetheless does not claim to endorse UT. 16. Steadfast positions are defended by Plantinga (1995/2000), van Inwagen (1996, 2010), Rosen (2001), Kelly (2005, 2010), Wedgwood (2007, 2010), Moffett (2009), Elgin (2010), Enoch (2010), Sosa (2010), and Weatherson (2013). 17. For instance, Rosen (2001), Wedgwood (2007), and Sosa (2010) claim that each of the disagreeing parties can reasonably or rationally hold his ground, while Kelly (2005) maintains that only one of the parties can do so. Kelly (2005) argued that one should give no weight to the opinion of one's opponent, a view he abandons in Kelly (2010). It is not clear to me whether or not Rosen, Sosa, and Wedgwood think that each of the disputants should give no weight to the opinion of his rival. 18. As far as I can tell, Kelly (2005) understands reasonableness or rationality in the first sense, whereas Wedgwood (2007) and Sosa (2010) understand it in the second. 19. Lackey thus rejects Independence, since she thinks that one can prefer one's own belief about the disputed matter by appealing to the very grounds for the belief (see Lackey 2010a: 324). 20. This view has been adopted, via different routes, by Bergmann (2009), Feldman (2009), Roush (2009), Enoch (2010), and Kelly (2010). 21. On this distinction, see Rescorla (2009a, 2009b). 22. See, e.g., Barnes (1990: ch. 1), Annas (1998), and Machuca (2011). 23. To the best of my knowledge, the only exception is Lammenranta (2008, 2011a, 2011b). 24. On the different versions of the argument from moral disagreement and the question of whether it succeeds in undermining moral realism, see, e.g., Mackie (1977), Brink (1984), Tolhurst (1987), Tersman (2006), Doris & Plakias (2008a, 2008b), Enoch (2009), and Sneddon (2009). 25. See McGrath (2008), and the discussion between King (2011a, 2011b) and McGrath (2011). 26. See, e.g., Gutting (1982), Plantinga (1995/2000), Schellenberg (1994, 1997), van Inwagen (1996), Hick (2001, 2004), and Feldman (2003). For an excellent overview, see King (2008). 27. See Christensen (2009b), Feldman & Warfield (2010), and Christensen & Lackey (2013). 28. See Goldberg (2009), Frances (2010, 2013), Fumerton (2010), and Kornblith (2010). 20 Diego E. Machuca 29. I am grateful to Nathan Ballantyne, and especially Nathan King, for their helpful comments on an earlier version of this chapter. Their feedback led to substantial improvements. REFERENCES Annas, J. (1998). 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