One of the appealing aspects of Jonathan Matheson’s book is its explicit defense of a disagreement-based skepticism. Although some of the authors who in the past few years have engaged with the epistemic significance of disagreement have adopted what may be regarded as skeptical views, this is the exception rather than the rule, and those authors are for the most part reluctant to describe their views as skeptical. The reason is that in the literature on the epistemology of disagreement skepticism is deemed absurd, untenable, or even damaging. The philosophical milieu in general considers it an intellectual sin to adopt any form of skepticism that is not both narrow and innocuous to our most cherished beliefs. This perhaps explains why Matheson himself is reluctant to (fully) embrace the radical skeptical consequences of his position. My aim in this short essay is both to critically examine the nature and extent of his disagreement-based skepticism and to consider three ways not discussed by him in which disagreement may pose, or contribute to posing, skeptical challenges. The essay will therefore be organized around four issues.

To begin with, what does Matheson’s disagreement-based skepticism consist in? It consists in part in his adoption of the conciliatory stance known as the Equal Weight View (EWV) in the face of disagreement between epistemic peers, which is a type of idealized disagreement (chs. 4 & 5). This is a skeptical position inasmuch as, on a coarse-grained approach to doxastic attitudes, it recommends that judgment always be suspended when confronted with a peer dispute. However, it is a purely theoretical or artificial form of skepticism in that it does not tell us how to cope with the disputes we constantly come across in everyday life. So the adoption of a skeptical stance in the face of idealized disputes does not imply or entail the adoption of a skeptical stance in the face of real-life disputes—or “everyday” disagreements, as Matheson calls them. In fact, some authors may be willing to adopt an “ethereal” disagreement-based skepticism in part because they think that such a stance cannot be carried over to real-world controversies. This is not Matheson’s case, since he claims (rightly, in my view) that even in the face of real-life disputes one is required to suspend judgment on account of the fact that, though there are typically epistemic asymmetries between the contending parties, it is often not clear which party is in the better epistemic position on the disputed matter (116). Now, what is the scope of this real-world disagreement-based skepticism? At the outset of the book, Matheson claims that

awareness of widespread disagreement on controversial issues in religion, philosophy, politics, and science has the consequence that we are much less epistemically justified in our controversial beliefs on those matters and that we often are not epistemically justified in holding them at all. (2)

Although the first consequence might be regarded as a form of mitigated skepticism that partially calls into question the epistemic justification of the controversial beliefs in question, I take it that Matheson considers only the second consequence as strictly skeptical, as seems to be confirmed by his claim that we should be skeptical about “a number of controversial claims” in the above areas (17). At one point he broadens the scope of his skepticism in saying that we are justified in suspending judgment about “many” of such controversial claims (128–29). He also points out that the skepticism recommended by EWV is restricted to “highly” or “heavily controversial propositions” (140–41, 146, 164).1 If I interpret him correctly, the reason skepticism is restricted to many, or a number of, controversial issues in politics, philosophy, religion, and science is that, regarding other issues in these areas about which laypeople disagree, there is nonetheless widespread agreement among experts (cf. 128).

Matheson is concerned to make it clear that his view is not a form of radical skepticism. Consider these initial remarks:

By stating that justification is “real,” I mean that the radical skeptic is mistaken. I am taking it that we can be justified in believing propositions about the external world, about morality, philosophy, science, and so forth. That is, there is no barrier to being justified in believing propositions on these matters, at least not in principle. That said, the view defended in this book has it that we are justified in believing many less propositions than we typically think. (9, cf. 141)

Also, when presenting his stance on real-world disagreements (ch. 6), Matheson tackles the objection according to which the principle of independence2coupled with his claim that, though it is doubtful that any two subjects are epistemic peers, it is in general difficult to establish which of the disagreeing parties is in the better epistemic position seem to leave one “epistemically doomed to radical skepticism” (117). He offers two responses (118). First, one can have recourse to other people’s opinions about one’s beliefs concerning the disputed matter, opinions that constitute a reason independent of one’s own reasoning about the matter. If they agree with one, then even though one’s disputant may reject their opinions, there is an important asymmetry in numbers. Second, one often possesses information about oneself—which is also independent of one’s reasoning about the disputed issue—that one lacks about one’s disputants. With respect to the first response, it should be noted that, at least regarding many disputed issues, numbers vary with the circumstances and we do not often have access to, or know about, all those who have, or may have, an opinion about the matter under dispute. Matheson himself later makes what I think are similar considerations in connection with the difficulty in determining the distribution of opinions about a disputed matter (129). As for the second response, one can apply the same considerations he makes in relation to private evidence (118–19): just as I can appeal to the information I have about myself to dismiss my disputant’s belief about the disputed matter, so too can he appeal to the information he has about himself to dismiss my belief about it. Although Matheson does not make the distinction in this context, it is useful to distinguish between the first- and the third-person perspectives. From the perspective of a third-party onlooker, it is clear that in this case there is epistemic symmetry between the contending parties. But there seems to be epistemic symmetry even from the first-person perspective of those involved in the disagreement in case they become aware of the fact that both have access to their own personal information and can reason likewise in dismissing their rival’s opinion. Such awareness would be a part of their total body of evidence. Hence, Matheson’s view does seem to lead to a strong form of skepticism.

In chapter 7, devoted to addressing the objections raised to EWV, Matheson returns to the question of skepticism. He considers the objection according to which that view has skeptical consequences that “are simply too great” (140). Part of his response consists in “softening the blow” of those consequences (144), and part of this “softening” consists in pointing out that he has been concerned only with the kind of epistemic reasons upon which epistemic justification depends:

None of these skeptical conclusions have any implications for what inquiries you should undertake, what research is profitable, what you should publish on, and so forth. The skeptical consequences infect only what doxastic attitude you are justified in adopting toward various controversial claims along the way. Controversial claims are still worthy of our attention. Research, inquiry, and public defenses of a claim do not require one to justifiably believe the claim in question. (144–45)

It is plain that these remarks would not comfort those deeply concerned with what they take to be the damaging skeptical consequences of EWV. For not only do they want to keep inquiring into controversial matters in politics, religion, science, and philosophy, but they want above all to hold epistemically justified beliefs about those matters. Matheson might be aiming to pacify the anti-skeptical objectors when he goes a step further and claims that

it may even be that intellectual developments out of conflict are best brought about when individuals believe the views that they are defending. In fact, psychological data regarding group inquiry indicates that groups that hold conflicting beliefs are more successful in their inquiry regarding the disputed proposition(s)…. What this indicates is that there are even good epistemic reasons to believe controversial propositions.…[T]hey simply are not the kind of epistemic reasons concerned with epistemic justification. (145)

I fail to see the plausibility of Matheson’s view. I suspect that, in the psychological studies he refers to, the individuals holding conflicting beliefs had not suspended judgment about the disputed matters, as does Matheson’s disagreement skeptic. Can one believe that p, and not simply keep inquiring into p, when one is aware that belief is not the doxastic attitude epistemically supported by the total body of available evidence bearing on p? Perhaps this is psychologically possible, and determining whether it is so depends on empirical research, about which I unfortunately have nothing to say. I will only observe that it seems more plausible to adopt some sort of fictionalism: for both pragmatic and epistemic reasons, one might come to the conclusion that it is worthwhile to pretend that certain controversial beliefs are epistemically justified when in fact they are not. I am sure that such a fictionalist stance will not appease those voicing deep concern about the skeptical consequences of EWV, but I do not believe this is a problem.

Even if we grant that Matheson’s disagreement-based skepticism is not radical with respect to its breadth, since he intends it to be restricted to highly controversial issues, it is clear that it is radical with respect to its depth, since the controversial issues it targets are probably among those that concern us the most. Consider also Matheson’s view on one particular case of extreme disagreement, namely, that about the truth of the proposition “2 + 2 = 4” (98–101). He claims that there are three possible reasons for thinking that one’s justification for believing that proposition is unaffected by being justified in believing that one is in an idealized disagreement about it, none of which provides, in his view, a defeater-defeater: it is a necessary truth; not only is it a necessary truth, but it is also believed to be so; the evidence very strongly supports that one is justified in believing it. This extreme disagreement is an idealized disagreement, and hence the skepticism about the truth of 2 + 2 = 4 is purely theoretical. But I imagine that most people would deem this skepticism to be threatening inasmuch as the justification for believing in mathematical propositions would seem to rely on contingent facts. Indeed, in order to dismiss the first two reasons for thinking that one has a defeater-defeater that nullifies the call to be conciliatory, Matheson appeals not to skeptical hypotheses, but to the fact that philosophers disagree about propositions they believe to be necessary truths, such as those concerning epistemic justification or the connection between free will and moral responsibility. One might then think that, on Matheson’s view, if at some point quite a number of philosophers or mathematicians started to deny that 2 + 2 = 4 and there were thus a real-life dispute, one would have to suspend judgment about its truth. No doubt will most people be uneasy with Matheson’s view, since they take it that one is justified in believing that 2 + 2 = 4 because one sees its truth through intuition or rational insight, and that on this basis one can definitely affirm that someone who denies that 2 + 2 = 4 cannot be one’s epistemic peer. Matheson explicitly discards this proposal as unsatisfactory (106–7). He claims, however, that were one to gain evidence in real life that someone disagrees with one about such obvious propositions, one “would also gain evidence independent from the mere fact of disagreement that the party is malfunctioning” (107). He emphasizes that the reason to dismiss the dissenter’s view provided by such additional evidence “would not come simply from the mere fact of disagreement . . . ; it would come from other information that was gained about the interlocutor in the process of discovering the disagreement” (108). Most people would find this comforting strategy too precarious, because they believe that one can be certain of the truth of the proposition that 2 + 2 = 4 solely on the basis of the evidence directly pertaining to it, even in the face of the higher-order evidence provided by a disagreement about it. They would find equally precarious Matheson’s further claim that in real life another reason independent of the disagreement to dismiss the opinion of someone who believed that 2 + 2 ≠ 4 would come from the awareness of the vast agreement about the sum of 2 and 2 (108).

The second issue I would like to discuss concerns the so-called Agrippa’s trilemma, which Matheson nowhere considers and which might be part of the new directions that research on the epistemology of disagreement might take (ch. 8, sect. 1). In his Pyrrhonian Outlines (1.164–77), Sextus Empiricus presents three sets of modes designed to induce suspension of judgment. One of these sets is the one known as the Five Modes of Agrippa: disagreement, relativity, reciprocity, infinite regress, and hypothesis—these last three constituting the trilemma. Although Sextus sometimes uses the mode from disagreement to induce suspension independently of the trilemma, he often uses it in conjunction with the trilemma: the mode from disagreement presents the material upon which the trilemma operates by blocking any attempt at resolving the dispute under consideration. Agrippa’s trilemma has been the object of much discussion in contemporary epistemology as posing the justificatory challenge that has come to be known as the “Pyrrhonian problematic.” Curiously enough, almost no attention has been paid to the mode from disagreement among epistemologists discussing the Pyrrhonian problematic. Equally curious is the fact that the trilemma has received almost no attention in the literature on the epistemic significance of disagreement. The reason is perhaps that appealing to it in the analysis of how to resolve disagreements would look odd or artificial. But if this were the reason, it should be noted that it would not be more odd or artificial than examining idealized disputes in the discussion of the epistemic significance of disagreement, or examining the trilemma in the discussion of theories of knowledge and justification. Now, consideration of the trilemma is important because it could be argued that, even if one left aside peer disagreement for being highly idealized, epistemic symmetry can be achieved in the case of real-life controversies by applying the Agrippan modes: in defending their view in the dialectical context of disagreement, each contending party falls into an infinite regress, or reasons in a circle, or makes an arbitrary assumption, and when attempting to escape from one of these traps, they fall into the other two. I would be interested to know both whether Matheson takes the justificatory challenge posed by the trilemma to be part of the general skeptical worries he sets aside in the book (115, cf. 9), and particularly whether he agrees with me that consideration of the trilemma would enrich the current epistemological inquiry into the significance of disagreement.

The third issue I would like to briefly address is that of basic epistemic disagreements. Matheson refers several times to disputes between laypersons and experts, mainly scientists (e.g., 19–20, 120, 126), pointing out that it is plain that the former should defer to the experts’ opinions. Leaving aside that even in such disputes one could make use of the Agrippan trilemma, we do typically take it as unquestionable that one should defer to the opinion of an expert in a given field, particularly in the hard and natural sciences. Of course, at present quite a number of laypersons call into question scientific experts’ opinions about, e.g., the benefits of vaccination, but those laypersons’ view are taken to be caused by ignorance or blindness to the evidence. Other cases seem to be different. Consider, first, the disagreement between scientists who defend evolutionary theory and those religious believers who defend the intelligent design theory. This disagreement is due to the fact that the parties defend conflicting basic epistemic principles and disagree about what is a reliable source of information or a reliable method of inquiry. Those who defend the intelligent design theory call into question the very status of expert of those who defend the theory of evolution. Deep disputes of this kind do not seem epistemically resolvable insofar as the basic epistemic principles in question cannot be defended, when challenged, by means of noncircular reasons. Note, secondly, that whereas quite a number of fine epistemologists not only are religious believers but also defend the rationality of religious beliefs—particularly, Christian beliefs—at least many scientists regard belief in a personal God, miracles, or Marian apparitions as being as irrational as belief in astrology, cartomancy, or witchcraft. Here too we seem to be confronted with a basic epistemic disagreement. It would be interesting to know what Matheson thinks of disagreements of this kind, in particular whether they do not call for a wider disagreement-based skepticism.

I move on to the final issue. In the introduction (2–5), Matheson briefly addresses the prospect of adopting either a relativistic or an anti-realist stance in the face of disagreement. In the case of anti-realism, he focuses on moral non-cognitivist anti-realism (4–5), according to which moral claims are not propositions or assertions—and hence are neither true nor false—but prescriptions or expressions of emotions. Matheson claims that

rather than being supported by the disagreements in some domain, anti-realist views must posit that we do not have cognitive disagreements in that domain. To the extent that we have reason to believe that there are genuine cognitive disagreements in a domain, we also have reason to be realists about that domain. (5)

I consider this issue because in metaethics anti-realism is viewed as a form of skepticism, namely, as ontological moral skepticism. Epistemologists tend to deny that moral anti-realism is a form of skepticism because they take skepticism to be an exclusively epistemic affair. However, viewing moral anti-realism as a skeptical stance makes sense insofar as, in denying the existence of moral facts or properties, one undermines the truth of moral beliefs and hence their epistemic justification. Now, Matheson does not consider the moral skepticism of J. L. Mackie, who defends cognitivist moral anti-realism: basic moral claims are propositions but they are all false.3 I would like to know if also with regard to cognitivist moral anti-realism Matheson believes that moral disagreement points to objectivity, for Mackie does not deny that in moral disagreements the rival parties adopt incompatible doxastic attitudes toward a proposition that is truth-apt.

Disagreement is a common feature of our interpersonal relationships. Its prevalence is, perhaps, one reason its epistemic significance has only recently garnered philosophical attention; we disagree so often with so many others that we could easily fail to recognize, in virtue of its being an indelible facet of our epistemic lives, disagreement’s unique epistemic features. Jon Matheson’s book is a pleasure to read not only because he aims to elucidate disagreement’s epistemic significance, but also because he moves the discussion from idealized cases to real-world scenarios. Jon’s thorough and clear analysis of ideal disagreement paves the way for his insightful discussion of the role peer disagreement should play in our daily lives. Jon’s project has encouraged me to think more deeply about epistemic peers, and so in turn I now invite Jon to think alongside me as I propose two critical curiosities—the first I offer because I harbor skepticism about the possibility of epistemic peers and the second because I think reconsideration of one seemingly inconsequential stance would enrich and expand his project.

Peers: Impossible or Improbable?

I will put my first question sharply: do epistemic peers exist? Jon initially refers to Thomas Kelly’s account of epistemic peers to later discuss idealized disagreements. “Two individuals are epistemic equals with respect to some question,” Jon quotes, “if and only if they satisfy the following two conditions: (i) they are equals with respect to their familiarity with the evidence and arguments which bear on that question, and (ii) they are equals with respect to general epistemic virtues such as intelligence, thoughtfulness, and freedom from bias” (21). Although Jon does a thorough job noting the nuances and caveats of this definition, he nonetheless leaves readers with a conflicting message. At times Jon suggests that epistemic peers not only exist, but also that it is possible to know when we have encountered a peer: e.g., when Jon says that he has never disagreed with an epistemic peer, he implies both that he has an epistemic peer to disagree with and that he was able to identify this peer. Yet other times Jon explicitly states that it is highly unlikely that epistemic peers exist, and he is often reluctant to claim that we can know when we have encountered our peers.

I ask Jon whether or not he thinks epistemic peers exist in part to satisfy my curiosity and in part because I think his answer will have implications for his larger arguments. For many, philosophizing about disagreement is worthwhile only if epistemic peers actually exist. If there are no epistemic peers, disagreement can be explained by one party’s objective epistemic position relative to her interlocutor. Of course—and Jon makes this clear—disagreement is also worth discussing if it is impossible or extremely difficult to know which party is in the better epistemic position. While we can hypothesize epistemic peers in idealizations, we often find ourselves in scenarios where it is difficult to discern who is in the best epistemic position. Even if we don’t have a definitive answer about the existence of epistemic peers, we can ask many of the same prescriptive questions in cases where there might be an epistemic asymmetry, but where it is not obvious whose beliefs should be given greater weight.

Jon does well to notice that we are often faced with situations where we are not sure if we are better placed than our interlocutor, but I wonder if he is subtly but meaningfully changing the definition of epistemic peer when he moves from ideal disagreements to real-world cases. I also wonder if he should argue for a new conception of epistemic peer. In cases where epistemic asymmetry is not obvious, Jon argues that we should give each party’s perspective equal weight just as we would if we encounter an idealized disagreement. But if ideal peers don’t occur in the real world, should we think that the notion of epistemic peer is simply reduced to our ability to discern our placement in an inevitable epistemic asymmetry? If epistemic peers do exist in the real world, should we really treat real and merely apparent peers the same way?

It’s also worth having an answer to the question of the existence of epistemic peers because Jon spends so much time using idealized cases with ideal peers as a baseline for real-world scenarios. It is certainly an attractive strategy, and it can be interesting to think about ideal cases. If, however, ideal cases cannot or do not occur in the real world, we should ask if they have meaningful bearing on everyday cases, and we should ask if using them as a baseline is the best strategy for saying anything useful about real-world disagreements.

Revealing Epistemic Asymmetry

In what could be overlooked as a minor remark late in the book, Jon notes that “any relevant defeater-defeater will need to indicate that that subject is in a better epistemic position on the disputed matter. Without having such a reason, the mere existence of asymmetries in epistemic positions will not affect the call to split the difference” (118). Put another way: in cases where relative epistemic position is not obvious, we should ascribe each party equal weight, and doing otherwise would require some indication that the subject is in a better epistemic position. What is striking about this passage is Jon’s claim that the mere existence of asymmetric epistemic positions is not enough to affect his equal weight view. It is this point that I ask Jon to reconsider and expand upon.

On the one hand, Jon’s stated position makes sense: if we cannot tell who is in a better epistemic position, for practical purposes we should treat them as an epistemic peer, grant equal weight to both views, and only evidence speaking to which individual is in the better epistemic position would upset the call for equal weight. That is, only evidence revealing that an ostensible peer is not in fact a peer should call into question the equal weight view.

On the other hand, it is not obvious when equal weight should be granted to both parties. Jon says that we should grant equal weight when relative epistemic placement is not obvious, but at what point should we decide that our relative placement is not obvious?

I ask this question because there are many times when an epistemic asymmetry is present and would be apparent with minimal investigation. Indeed, I think that we engage in investigative acts of this sort all the time when we first enter into a dispute with someone. I have my beliefs, and in most cases if I am being epistemically responsible, I will converse with my interlocutor to see if there are reasons to think that she is in a better position. In this scenario I might not know at the outset who is in the better epistemic position, but minimal conversation would reveal our positions. But when should I ascribe equal weight? At the first sign of disagreement? Or could I, knowing that asymmetry is likely, withhold ascribing equal weight until it is apparent to me that uncovering the asymmetry would be impossible or unduly difficult?

Insofar as we might think that dissolving disagreement is just our ability to figure out who is in the better epistemic position, it matters how dedicated we are to uncovering the asymmetry. I worry that ascribing equal weight too early would at best stifle the investigation and at worst serve as misleading evidence for or against someone’s view. If ascribing equal weight ends the investigation too early, we could argue that this is epistemically irresponsible and not ultimately satisfying. If ascribing equal weight too early gives a kind of credibility to the other’s view when minimal conversation would reveal a vast epistemic disparity, this too strikes me as irresponsible. I don’t want us to get bogged down in the details of these conditionals; I merely use them as examples to suggest that it is not clear when it is most appropriate to implement the equal weight view, but the answer has consequences for Jon’s project that I’d like him to consider further.

Now, I take it that the kinds of cases Jon is most interested in are cases where it is not going to be easy to reveal the asymmetry. It is also important to remember that when disagreements occur in everyday life, our ability to engage in this investigative process is limited by many factors. Still, I’d like Jon to say more about how he envisions any standards or guidelines for his view in real-world cases. When should we adopt his view? Should we ascribe equal weight immediately when epistemic positions are not obvious and then keep investigating? Should we withhold equal weight until the time that we lack resources to continue uncovering the asymmetry? Does the time at which we adopt his view problematically affect the outcome of the disagreement?

In the end, then, I’d like to hear more from Jon on these particular issues but I would also like to mention that the questions I pose here all point to a larger issue that would enrich and expand Jon’s project regardless of precisely how he responds to my worries. Put simply: what responsibility, if any, do we have to discover the details of epistemic asymmetries in disagreements before we decide that we should be less sure of our own controversial beliefs?

Jon Matheson’s book The Epistemic Significance of Disagreement is clearly written and packed full of interesting arguments about the significance of qualified peer disagreement. The book’s aim is bold: convince us that “we are justified in believing many less propositions than we think” (9). Matheson’s boldness is admirable because if correct, we ought to be skeptical about our moral, political, religious, and even scientific beliefs. Such beliefs arguably lie at the center of our doxastic network, and abandoning them opens up the possibility for shock waves to reverberate through the entire network. But a bit of epistemic shock and awe might not be that bad even if it requires us to suspend judgment about our deeply cherished beliefs in controversial domains of inquiry.

Matheson’s view of what one ought to do epistemically depends solely on synchronic considerations: one’s total evidence at a time T irrespective of concerns for consequences to or qualities of one’s doxastic network. Among one’s evidence at T is the fact of disagreement with a qualified epistemic peer, and this fact is significant. Its significance derives from deeming one’s peer to be in equal epistemic position to oneself (22–24). Equality of position amounts to their ability to process the evidence and get the “right” conclusion about p. There are no contextual or other factors that would cause peerhood to fall out of the evidential mix so to speak (29). If that’s right, then disagreement with a peer provides one with an undefeated defeater for their doxastic attitude with respect to p.

Surprisingly, though correctly I think, Matheson explains, “[Qualified] peer disagreement is highly idealized—so much so that it is doubtful whether it ever actually occurs. Two individuals rarely, if ever, have equally good evidence regarding some claim. Further, they rarely, if ever, are equally good at processing that evidence” (33). Due to our agreement here, along with space limitations, I will focus my analysis on what Matheson has to say about “everyday disagreements” after we strip off the idealizations (114ff.). Does the fact of disagreement provide one with an undefeated defeater for their doxastic attitude toward p in everyday disagreements as he suggests? I think not.

After granting that all parties to a peer disagreement will lack the same evidence about p and also vary in their evidential processing abilities, Matheson goes on to argue that this asymmetry of epistemic position is insufficient to provide one with a defeater-defeater. Since “it is not clear which party is in the better epistemic position on the matter . . . there simply being a difference in the quality of epistemic position needn’t give either party a reason to give more or less weight to the other party’s opinion. . . . The mere existence of those epistemic asymmetries does not provide either party with a defeater-defeater, canceling the call to conciliate, if the parties are entirely unaware of their existence” (116).

Two responses to this argument are in order. First, there is nothing “mere” about the fact of our failing to share an equal epistemic position. Plausibly, one might argue, it is likely that nearly all peer disagreements in religion, politics, science, and morality include kinds and qualities of evidence that provide a significant asymmetry between the parties to the dispute. And it’s precisely our awareness of these differences that break the symmetry in evidential position in a significant way. Consider, for example, a case where you and your family have apparently lost a family member due to their plane having crashed in the Atlantic. After days of rescue efforts, the experts report that not a single survivor has been found. Much of the plane has been recovered, but for every passenger recovered, they’ve all been dead. For those not found, experts have urged families to wait for the bodies to hopefully wash ashore. On the basis of this evidence, and your knowledge that your family member can’t swim well, you all form the justified belief that this person is dead. A week after you formed this belief, your missing family member knocks on your door and discloses to you that she is alive but says she cannot stay long. Later that night you eagerly testify to your family about this person’s appearing to you, though they have left before others could “see for themselves” that they are alive. While your family has no reason to discount your testimony (you’re not prone to lying, hallucinating, etc.), they continue to believe the expert consensus (that there are no survivors) over your testimony; but you believe on the basis of your firsthand experiential evidence that your family member is alive.1

Two observations seem clear to me. On the one hand, it seems clear to me that the evidential inequality and each party’s awareness of this inequality is significant precisely because it is not “just here or there.” Your firsthand experiential evidence can rightly be given more weight than the testimonial evidence of the rescuers; whereas your family’s giving the testimonial evidence of the experts more weight can be seen as right. The divergent responses by you and your family members is both understandable and epistemically above board. Both parties are aware of the evidential inequality here, and they are justified to believe as they do (and to remain steadfast in their beliefs) precisely because they are justified to give more weight to the kind and quality of evidence that is salient for them in the evidence processing and belief updating. On the other hand, one’s belief about the evidential inequality is a higher-order consideration about one’s first-order evidence. To see this, notice how considerations about evidential inequality do not and need not figure into one’s belief about p given E. An explanation about evidential inequality arises only after disagreement is known. Highlighting the fact of evidential inequality is like highlighting the fact of disagreement with a qualified peer—both are higher-order considerations about the evidence regarding p. If that’s right, then it seems to me that this higher-order consideration can count as a partial (if not a full) defeater for the defeater from disagreement. In other words, having a justified explanation about why we disagree and thereby fail to be in an equal epistemic position causes peerhood to “fall out” at least partially if not fully, so I need not conciliate.

Second, it seems to me that the evidential inequality here “seeps through” to my reasoning about your evidential evaluation capabilities, and this provides each of us with a defeater-defeater for disagreement. Consider the following argument. Suppose we grant equal evidential evaluative abilities to the other party. Plausibly we’re equals at least with respect to our having similar cognitive capacities qua human beings. If we add that we’re able to exercise those capacities the same barring any mitigating factors, we both look like Matheson stipulates even if we’re not in an idealized scenario. That is, I have every reason to think you are equally likely to get it right even though we lack the same perceptual, private, personal, or some other kind of evidence (116–19). Barring an extra special reason to think you are “inferior” in your abilities here, I still lack a defeater-defeater for disagreement. But we do have such a reason, and here’s why. Even if two or more parties have equal capacities for evaluation (qua being human), their lacking the same evidence entails their lacking the relevant kind and quality of evidence necessary to utilize those capacities to evaluate the p-relevant evidence. Since the capacities cannot be used in the relevant way and to the relevant degree at this time, one is justified to believe their peer is in an inferior epistemic position (qua utilization of particular human capacities) to oneself. After all, I am aware that my evidence is of a better kind and quality in my consideration of p, and this higher-order evidence seeps through to boost my status of position. If so, Matheson is mistaken to claim that I have no reason to think my capacities are better than yours and that the “epistemic effect of our disagreement remains unchanged” (117).

In addition, should one’s peers possess the same kinds and qualities of evidence to oneself, they would likely come to agreement with me about p. Not only would they have sufficiently similar evidence, they would also be able to utilize the relevant capacities to evaluate the evidence necessary for coming to agreement. Of course there is no guarantee, for as Matheson rightly points out, we are fallible knowers. It seems to me, then, that Matheson’s conditions (ii) and (iii) (the requirements of strict peerhood between the subjects and that the two have access to their own and each other’s’ evidence) can be stripped away; and when they are, the effect of disagreement on one’s justification is not as he argues. The deflated effect here is not due to a broadly spread distrust in one’s interlocutors (123). Rather, deflation occurs even if we take each other at our word, because we can’t in principle use the capacities the other is using to evaluate the unique kinds and qualities of evidence the other alone has access to.

My argument can be extended to nearly all cases of intractable disagreement in religion, philosophy, politics, etc. Generally there will be kinds and qualities of evidence from experience, testimony, etc., that provides a reason to think there’s an evidential inequality, and this seeps through to affect our equality of position in matters of processing. For example, moral philosophers and philosophers of religion often highlight their experiences (or lack thereof) to explain their beliefs about p. Contrast, for example, John Corvino and Robert George in moral philosophy and Alvin Plantiga and Daniel Dennett on religious knowledge. While I agree that “such inequalities will typically have the result, that one party is in a better epistemic position on the matter, they needn’t” (121), I am inclined to think my argument will apply more often than Matheson has suggested throughout his book. Stated bluntly, while everyday disagreement with a qualified interlocutor does not necessarily give me the kinds or qualities of evidence that will provide me with a defeater-defeater to enable me to remain steadfast, it is highly likely that it will more often than not. Here we must emphasize that this is good news not only due to the looming skepticism (128–34) of his view, but due to the centrality of these beliefs to our doxastic networks.

Matheson may reply along the lines articulated in multiple places throughout chapter 6: “The mere fact that there is some evidence that is unshared does not on its own create any epistemic asymmetry” (119). He may go on to say that even though we will often have a reason to discount our interlocutors on the basis of the kinds, qualities, and amounts of evidence, we need not, because “some evidential differences may be quite insubstantial” (121). I have two replies. First, I agree that generally evidential differences may not matter much, but in cases of intractable disagreement it seems that the evidential differences are quite substantial. If Plantinga claims to have experienced God, yet Dennett claims to lack this kind of experience, this matters in substantive ways in their assessment of whether God exists and how we might know such a being exists at all. Second, I agree that unshared evidence all by itself isn’t doing the epistemic heavy lifting. As I’ve tried to show above this kind of evidence isn’t “just here, there, or out there” so to speak. It’s not a “mere fact” as Matheson says. Rather, unshared evidence creates an asymmetry when it provides one with a salient reason with respect to p, and this reason is higher-order evidence, providing one with a defeater-defeater for disagreement. Notice I have not claimed the significance of the inequality is due to the evidence being mine. What is doing the epistemic work here is the kind and quality of evidence as such, not who possesses it. This explains how a steadfast proponent like myself might go on to say that all parties to the dispute are justified to maintain their same doxastic stance after disagreement, evidential inequalities, and epistemic position inequalities are considered. We can, after all, have justified false beliefs.

Multi-Party Disagreements and Diachronic Epistemic Considerations

How might the argument above fare when we consider Matheson’s discussion of multi-party disagreements? Intractable disagreements in religion, politics, ethics, etc., face what he calls “an explosion of higher order evidence” (128). Here one is aware of many expert opinions to give weight to, and this can affect one’s evidential position regarding p. One’s higher-order evidence might come by way of “epistemic election.” Functionally this is equivalent to polling the experts and tethering one’s belief to majority opinion on the matter. But there’s a “complication” Matheson rightly points out. Expert opinion is weightier to the degree that individuals’ opinions are arrived at independently of one another, and to the degree we can discern what to make of the election results (127–28).

Two observations are in order here. On the one hand, I am skeptical about there being any multi-party disagreements where the opinions are arrived at independently. Nearly every dispute in philosophy, etc., takes place within an ongoing conversation. Being a part of this conversation renders it highly unlikely that any conclusion one draws will be strictly independent of the views of others. Furthermore, one often has kinds and qualities of evidence that many in the election lack. As I’ve argued above, this can make a significant difference to the net impact of disagreement on one’s doxastic stance. Might this also apply in multi-party disagreements, whether or not my view is with the majority or the minority in the election results? It seems so, because the seepage of kinds and qualities of evidence to defeat my single interlocutor’s epistemic position could be extended to my contrary group in the election.

On the other hand, even if we grant that we should be skeptical about the election results, it would not follow we should suspend judgment about the propositions these elections are about (129ff.). The election results are just too complex and opaque to count one way or the other, and that’s why our evidence from them is not of a quality sufficient to discern what weight one ought to give each opinion or the entire election. But this is not the case for one’s other first and higher-order evidence about p. While I agree with Matheson that truth is an epistemic good, there are other epistemic goods related to our justification, and they are not reducible to synchronic epistemic or pragmatic concerns. Other epistemic goods include at least the following: (a) coherence among one’s beliefs and (b) stability in one’s doxastic system. I suggest that if we have good reasons to think p, we have kinds and qualities of evidence that partially defeat the purported defeater from disagreement, and there’s some diachronic consideration applicable to my stance toward p, I am justified to remain steadfast about p even when an epistemic election looms large.

Suppose that Plantinga and Dennett disagree about God’s existence. Each is aware of the p-relevant evidence, and each has come to their belief about p prior to disagreement being known. Each is prima facie justified to believe as he does. They get together and compare notes, and each has crucially different kinds and qualities of evidence than the other philosopher. Plantinga reports that he’s had religious experiences that figure in while Dennett has not; and Dennett has experienced or is aware of certain kinds of evils that Plantinga has not. Besides their disagreement being known, each is aware of many other philosophers that have thought about this issue and take varied stances on the matter. Now at T1 when they discuss all of this, it’s unclear what they’re to make of an epistemic election that’s recently been published on a noted philosopher’s blog. As a result, each is inclined to remain steadfast in his original belief. How should we evaluate the epistemic situation?

According to Matheson, we are to evaluate the situation as each philosopher having acquired a defeater for their prima facie justification two ways: via disagreement and the epistemic election. I demur. Each is justified and reasonable to remain steadfast in his original belief for two reasons.

First, justification is partly dependent on synchronic concerns such as one’s evidence at a time and whether one is epistemically well-positioned. Each meets the requirement for having good evidence for p as far as each can tell from the first-person perspective. Also, each has a reason to think their interlocutor is not as well-positioned to oneself. So, it seems their prima facie justification at T1 is still undefeated.

Second, justification and the positive epistemic status of one’s beliefs is partly dependent upon diachronic considerations. If one’s beliefs have positive epistemic status at an earlier time (prior to disagreement being known), this has a partial role to play in our epistemic evaluation at a later time. This point is broadly analogous to concerns in the free-will and moral responsibility discussion. On some views, one’s responsibility at T1 is partially dependent upon whether they had a role to play in the formation of their character that contributed to performing the action at T1. If they did contribute in the relevant way at an earlier time, then their responsibility at a later time receives an evaluation partly dependent upon these diachronic considerations. Why not think of justification in light of disagreement and the epistemic election in a similar way. If one comes to the dispute with prima facie justification for p, and there are other diachronic considerations that bear on p, then one is justified to remain steadfast. For example, if one considers the doxastic impact of moving to a skeptical stance on the basis of an opaque and complex epistemic election, and if one regards overall network stability as valuable as having truth-aimed beliefs, one has a diachronic reason for remaining steadfast until she can figure out how best to weigh the results of the election. Since either party could have diachronic features at their disposal, both parties could be justified to remain steadfast about p.2

Professor Matheson has written a fine book on disagreement. Matheson’s main concern appears to be practically weighty: “Given that disagreements exist and that we are aware of them, what affect, if any, should our awareness of them have on what we believe?” (2). Matheson motivates his discussion with the idea that we need guidance or advice, taking the form of epistemic principles or norms, in order to rationally respond to our awareness of widespread disagreement. He’s concerned with the “real-world implications” (113) of his epistemological theorizing. His idea is that by reflecting on disagreement, we can improve our intellectual lives by making our opinions more rational.1

To that end, one central part of Matheson’s discussion is to build a kind of bridge between abstract, idealized questions about disagreement and the practical, “real-world” questions that motivate reflection on disagreement in the first place. The idealized questions are raised by “toy” cases featuring thinkers who disagree under uncommon conditions. For example, one of Matheson’s idealized conditions holds just when two thinkers each have “access to their own evidence, processing of it, or resultant attitudes relevant to [some proposition p at a time t], and this access is no better or worse than the access to the other individual’s evidence processing of it, or resultant attitudes relevant to p at t” (29). By stipulating that such a condition holds for two thinkers in a dispute, Matheson then examines the normative judgments we would make about the thinkers’ dispute. He then uses those judgments to construct a theory about the normatively appropriate response to learning about disagreement under the idealized conditions.

But, as Matheson contends, actual disagreeing thinkers will only rarely, if ever, satisfy each of the idealized conditions. That being so, he observes that it is a “curious fact that while the debate over the epistemic significance of disagreement is typically motivated by looking at real-world . . . disagreements, nearly all of the literature has focused on the highly idealized cases of peer disagreement” (113).2 Thus, after exploring idealized disagreements (see chs. 2–5), Matheson relaxes the idealized conditions and applies the conclusions he has gleaned from reflection on idealized cases to some non-ideal ones. The idealized cases are supposed to help illuminate how learning about disagreement should determine what is rational for us to believe in everyday disagreements (see chs. 6 and 7).

Matheson rigorously defends the view that when we learn that we disagree with intelligent, thoughtful people, we should quite often significantly revise our opinions (see 128ff.). I think that Matheson’s general normative proposal is quite plausible: reflecting on controversy should make us more modest about the extent of our knowledge and rational belief.3 But here I will comment briefly on Matheson’s effort to bridge the ideal and the non-ideal in the epistemology of disagreement. He suggests that reflection on disagreement can make our intellectual lives go better and that his project is motivated by precisely that alleged benefit. While I agree that epistemology should try to guide thinkers, we need to proceed cautiously when we make assumptions about what is required to reliably guide thinkers.

As I have noted, one purpose of Matheson’s theorizing in his book is to improve our controversial opinions. Matheson attempts to guide actual thinkers with various principles (or norms or reasoning schemas) for reasonably thinking about our controversial beliefs. But are his principles a good way to do that? I am unsure how to answer, even supposing his principles are correct. That is because, in general, it is easy to doubt the power of philosophical principles and reasoning to guide our thinking. If epistemological principles are not a reliable way to guide thinking, however, then it’s unclear whether Matheson can deliver the touted benefits of his epistemological reflection on disagreement.

For philosophers hoping to use principles to guide thinking, history offers cautionary tales. For example, in Discourse on Method Descartes professed his intention to “follow my reason in everything” (1637: ii, 21). For him that meant abiding by rules, one of which is to make careful, exhaustive reviews of evidence so he could be “assured of having omitted nothing” (ii, 18). Declarations aside, the truth is that Descartes was often uninterested in studying works by other scholars. Friends, admirers, and critics often sent him copies of books and manuscripts. Usually he ignored them. One biographer noted that “throughout his life he read few books, and he consistently avoided as much as possible the company of those who were regarded as learned” (Clarke, 2006: 68). Descartes’ inspection of the available evidence was a bit less exacting than the letter of his method might have suggested.

Of course, the Frenchman is not the only philosopher to fail to follow principles. In a well-known section from A Treatise of Human Nature, David Hume said he had been driven to skeptical doubts after reflecting on the “manifold contradictions and imperfections in human reason” (1738: 1.4.7.9). His philosophical thoughts pushed him to reject all of his beliefs, inducing a kind of intellectual paralysis: “Where am I, or what? From what causes do I derive my existence, and to what condition shall I return?” Hume was confounded by these questions, but his crisis was short-lived. After a dinner out with friends and a game of backgammon, he reports his bout of “philosophical melancholy and delirium” was cured. But his doubts were not dispelled by arguments or reasoning. It’s just that, once Hume left his study, his skeptical reflections ceased to grip him.

As these stories imply, approving of principles (or at least claiming to approve of them) is insufficient to be guided by them. Descartes seemed to endorse a method he did not follow often enough. His conduct revealed hypocrisy—saying one thing, doing another. Hume may have suffered from a kind of intellectual akrasia, when he believed something against his better judgment. Out of the crooked timber of humanity, no straight epistemic agent was ever made. The prevalence of intellectual failings like hypocrisy and akrasia pose a practical problem for epistemologists who aim to guide thinkers.

I should note that the general problem here is not exclusively for epistemologists. Philosophers since Socrates’ day have often said that moral reflection encourages people to be morally better. Many ancient philosophers thought that reason could directly motivate human action, so that theories and arguments could literally “steer” or “pilot” the philosopher’s life (see Cooper, 2012: ch. 1). Although the assumption that reason motivates action is not commonplace today, it is still true that many ethicists say the practice of moral philosophy is somehow tied to leading a moral life. But is there any reason to believe that contemporary ethicists live any better on average than the rest of us? Eric Schwitzgebel and Joshua Rust have noted some reasons for pessimism. In one study, Schwitzgebel (2009) compared the rate at which obscure ethics books—ones most likely to be borrowed exclusively by professors and advanced students of philosophy—were likely to be missing from academic libraries compared to non-ethics philosophy books. He found the ethics books were at least 50 percent more likely to have walked away from libraries than non-ethics books. Schwitzgebel notes that “in one domain in which ethicists could have displayed superior conscientiousness, honesty, and concern for others’ property, they failed to do so” (723). Compared to their non-ethicist peers, ethicists as a group were apparently less reluctant to use the five-finger discount.

Though I don’t know of any empirical studies of contemporary epistemologists’ tendency to live up to their principles, we can safely assume they too are an imperfect bunch. But here is one important detail: epistemologists’ tendency toward intellectual hypocrisy or akrasia poses no special problem for the majority of epistemologists at work today. That’s because most epistemologists apparently do not aim to guide thinking. Many popular epistemological theories would be successful, on their own terms, by accurately describing facts about the nature of knowledge, epistemic justification, evidence, and the like. Epistemologists who articulate and defend such theories are not trying to “do” anything with their theories. Their aim is to describe something, period. But Matheson apparently practices a different brand of epistemology. He is trying to improve intellectual life by describing correct epistemic principles. So he faces a practical challenge.

Here is one way to describe the challenge. Epistemic theories are abstract things. They are expressed in words or symbols and reflected on during quiet moments. But belief and inquiry saturate our waking life. We are opinionated, noisy, busy, distractible, and animated by the subterranean forces of our nature. Epistemological theories like the one Matheson has developed in his book are supposed to influence our opinions, but how can they do that, given the nature of epistemic theories and the vicissitudes of our lives? What must epistemological theories be like in order to reliably guide creatures like us?4

I believe epistemologists who aim to develop intellectual guidance must try to answer those questions. (I try to do so myself in a book manuscript, but I’ll leave my answers aside here.) If our motivation for reflection on disagreement is to improve our intellectual lives by guiding our thinking, and if our chosen means to that end is principles, we need to say more about how those principles guide. Fully bridging the ideal and the non-ideal requires grappling with that issue.

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