1. Introducing Deep Disagreement

Consider the following case:

Let's say that disputants are in an ordinary disagreement when they disagree over p, p is a non-normative matter of fact, and that disagreement is best characterised in terms of the disputants having conflicting beliefs about p. Ordinary disagreements are just that – the stuff of everyday intellectual life, social-epistemic interactions, conversations, debates, and conflicts. On the surface, conspiracy resembles an ordinary disagreement. Tessa and Connie disagree over the proposition ‘Covid-19 was created in a lab’, that proposition refers to non-normative matters of fact, and it is apt to describe Tessa's and Connie's attitudes towards this proposition in terms of belief. Whilst, however, Tessa and Connie's disagreement resembles an ordinary disagreement at the level of belief, there is an underlying difference in terms of the kinds of consideration that each treats as relevant to determining the truth. I.e., Connie has a predilection for believing intentional explanations of events and phenomena, Tessa does not share this predilection. Crucially it is this underlying difference that explains how the two have come to disagree.

conspiracy is an example of deep disagreement. Other examples discussed in the literature include disagreements between practitioners of alternative and conventional medicine; disagreements over climate change (Kappel Reference Kappel2021); disagreements between those who follow scientific principles and those who follow the authority of religious texts (Lynch Reference Lynch, Haddock, Millar and Pritchard2010; Kappel Reference Kappel2012; Matheson Reference Matheson2021; Pritchard Reference Pritchard2021); and disagreements between people on opposite sides of the political spectrum (Pritchard Reference Pritchard2021).

Discussion of such disagreements has coalesced around several questions. We might describe these as follows:

It should not be surprising that these questions are, at times, treated as interconnected. For instance, Matheson (Reference Matheson2021) and Ranalli (Reference Ranalli2020) address the incommensurability question via consideration of whether those party to deep disagreement are permitted to continue believing the relevant propositions or whether they ought all to suspend judgement on those propositions. Both, then, proceed from the presumption that the normative and incommensurability questions are interdependent. Macintyre (Reference MacIntyre1977), Lynch (Reference Lynch, Haddock, Millar and Pritchard2010) and Kappel (Reference Kappel2012), on the other hand, introduce the practical question to discussion just because they posit that deep disagreements are irresolvable from the perspective of epistemic rationality. And so on.

At the same time, we should recognise that answering any one question does not necessarily settle any of the others. For instance, epistemic relativism need not entail that an individual agent is permitted to hold conflicting beliefs. So, the normative question remains open, even if the answer to the meta-epistemological question is yes. Deep disagreements may be rationally irresolvable without that implying anything specific about how one should respond to finding oneself in deep disagreement – practically or epistemically. And so on.

This paper addresses the normative question. Before turning to discuss that question proper, it will help to have an appropriate characterisation of deep disagreement in hand. I suggest that there are two features such a characterisation needs to capture if it is to be fit for that purpose. These can be described as follows:

NTN is important because many of us lack the theoretical and conceptual resources – let alone time and opportunity – required to uncover the kind of systematic difference in epistemic practices that we might associate with conspiracy or the other examples from the literature. Thus, if it were required that disputants realise or be able to realise that their disagreement is deep, vanishingly few disagreements would count as deep – including those taken to be paradigmatic of the class. ND is important on the presumption that those party to deep disagreement may face normative issues distinct from those posed by ordinary disagreement. Since, then, the loci of ordinary disagreements are beliefs about non-normative matters of fact, the loci of deep disagreements must lie with some other epistemically significant feature of the practices by which those party to such cases come to disagree.

With these features of deep disagreement in mind, what I suggest is that a natural way of describing deep disagreement is in terms of the epistemic norms that disputants followed in coming to disagree at the level of belief.Footnote ⁴

In general, following Boghossian (Reference Boghossian2008) and Littlejohn and Turri (Reference Littlejohn, Turri, Littlejohn and Turri2014), we might gloss epistemic norms as rule-like statements of the following form:

Let's say too that, when genuine epistemic norms have it that one ought to/ought not to/is permitted to F – the mandates of those norms will be indexed to whatever are the intrinsic success conditions of the relevant act. Most fundamentally, for instance, since belief aims at truth, genuine norms of belief encode conditions under which one ought to/ought not to/is permitted to believe p – for the sake of believing truths and not falsehoods.

In the simplest sense, I suggest, to say someone follows some specific norm is to say that they somehow regulate the relevant epistemic actions in accordance with what they perceive to be the prescriptions of that norm. Thus, to say a person perceives the situation as one in which a norm they follow requires or permits them to believe-p is to say that they perceive the situation as one in which they have reason to believe-p. To say they perceive the situation as one in which that norm proscribes against believing-p is to say they perceive the situation as one in which they do not have reason to believe-p. I shall give a fuller account of what it means to follow an epistemic norm in section 3. For now, the important points are that following an epistemic norm in the sense described is (i) something an agent does, not necessarily a matter of what they believe, and (ii) constitutively connected to what an agent treats as epistemic reasons. The former I take to be self-explanatory. The latter follows from the idea that questions about what we ought to believe are questions about what we have reason to believe. With this much said, we can characterise deep disagreement as follows:

Since following a norm is something that one does and not necessarily what one believes, and deep disagreements so defined come about via disputants following different norms, this definition fits with NTN. Since the loci of deep disagreements on this definition are differences in norms and since norm-following is directly relevant to questions about what we ought to believe, this definition fits with ND. To illustrate, let's return to conspiracy. Given Connie's favouring of intentional explanations, we might say that Connie follows the norm:

Given that Tessa does not, by default, favour any particular kind of explanation, we might say that Tessa follows the norm:

Crucially, as the case goes, Connie's norm says that a follower of that norm ought to believe ‘Covid-19 was created in a lab’. Tessa's norm mandates a follower of that norm to believe ‘Covid-19 was not created in a lab’. What explains the disagreement, then, is nothing so ordinary as a difference in evidence or personal-performance error. Instead, the disagreement is explained by the fact that Connie and Tessa competently followed the prescriptions of rival norms. Thus, even if neither Connie, nor Tessa have the theoretical resources that would allow them to think of it as such, their disagreement counts as a deep disagreement. Additionally, since deep disagreements on this definition entail – not only a difference at the level of norms – but a conflict in the beliefs that the disputants come to hold via following those norms, deep disagreements so understood are genuine disagreements. And since they are genuine disagreements, deep disagreements raise the normative question – i.e., epistemically speaking, how ought one to respond to the realisation of disagreement, when that disagreement is deep?

With this characterisation in hand, we are equipped to consider the normative question proper. Let's start by considering the general positions that theoreticians might take on that question.

2. Rational Options and Theoretical Positions

Since deep disagreements are constituted by differences at two levels (i.e., the level of norms and the level of beliefs), the ways in which disputants might respond to deep disagreement are complicated in a way they are not in ordinary disagreement. In the case of ordinary disagreement, the normative question is whether disputants ought to revise or retain their beliefs about the disputed propositions. In the case of deep disagreement, there are two such questions: Should the disputants revise or retain their original beliefs? And should the disputants continue to follow their respective norms? In contrast to the two possible responses to ordinary disagreement, then, there are four possibilities for how disputants might respond to deep disagreement:

1. (a) Stick by norms, retain beliefs.

2. (b) Stick by norms, revise beliefs.

3. (c) Reject norms, retain beliefs.

4. (d) Reject norms, revise beliefs.

As far as rational options go, we can immediately rule out (c). In the absence of support for believing as they do via some other uncontested norm, it will not be rational for someone engaged in a deep disagreement to reject their norms yet retain the beliefs formed in accordance with those norms. Consider Tessa in conspiracy. As the case is described, any reason that Tessa has for believing ‘Covid-19 was not created in a lab’ comes by way of her being permitted to follow the norm by which she came to hold that belief. Tessa's being rationally permitted to hold that belief, thus, entails that she is permitted to follow the relevant norm. Correspondingly, if, in the face of deep disagreement, Tessa ought to reject the contested norm, then, she will lose whatever reason she had to believe ‘Covid-19 was not created in a lab’ that came by way of her following that norm. And so, since she has no support for believing ‘Covid-19 was not created in a lab’ from another uncontested norm, it cannot be the case that Tessa ought to reject her norms and retain that belief. In other words, other things being equal, (c) is not a rationally viable response to the disagreement. More generally, this helps us to recognise the following principle:

(The ceteris paribus clause here reflects the possibility alluded to above that one may have an epistemically appropriate route to the same belief via some other norm.)

I shall return to the significance of this principle shortly. First, a note on the plausibility of (b). Like (c), (b) calls for a different response at the levels of norms and beliefs (i.e., stick by norms, revise beliefs). However, unlike (c), (b) will be appropriate in some cases of deep disagreement. This is for the simple reason that epistemic norms can be defeasible. To say that norms are defeasible, is just to say that one can be in the situation where one has no reason to reject one's norms in any general fashion, but one ought to withhold from following the prescriptions of those norms in the specific context. The mixed response at (b) should be understood in this way. (To pre-empt the later discussion, (b) may be appropriate in some cases where the disputants are not in a position to realise that their disagreement is deep.)Footnote ⁶

Given these points, then, (a), (d), and (b) – properly understood – are all theoretically viable responses. Leaning on terminology from the literature on ordinary disagreement, let's label (a) the steadfast response to deep disagreement, and (d) the conciliatory response.Footnote ⁷ And, in so far as it requires conciliation at one level and steadfastness at the other, let's label (b) the mixed response to deep disagreement. With that said, we can categorise the possible views of deep disagreement in terms of the range of cases in which they prescribe or permit these different responses. So, we can call accounts that prescribe the conciliatory response in all cases uniform-conciliationist views of deep disagreement. Accounts that permit at least one disputant to stay steadfast in all cases we can call uniform-steadfast views. (Or, at least in all cases where it is not so that neither disputant was permitted to follow the relevant norms to start with.) Finally, we can recognise the possibility of non-uniform accounts of deep disagreement, whereby which of the steadfast, conciliatory, or mixed responses is appropriate will depend upon the circumstances of the particular disagreement. In sections 3–5, I offer an account of what it is to follow a norm that supports a non-uniform view of deep disagreement.

Before doing so, it is worth considering some motivations we might have for endorsing a non-uniform account of deep disagreement independently of the merits of the account to follow.

Consider the principle of Total Revision. On a uniform-conciliationist account of deep disagreement, this principle would apply in all cases of deep disagreement. In a case such as conspiracy, however, this would have wide-ranging and comprehensive sceptical consequences. Why? Because, whilst the disagreement between Tessa and Connie concerns biological and political matters, the norms that explain that disagreement are not specific to those domains. As described, Connie's norm mandates favouring intentional explanations in any and all instances where such explanations are salient by her lights. Tessa's norm rules out such a general bias. Thus, if uniform-conciliationism is correct, Tessa and Connie should, according to Total Revision, withhold judgement on any and all issues in which non-intentional and intentional explanations support different conclusions. Just as Tessa's and Connie's norms are fully general, however, they are such that we might expect swathes of disagreement between followers of those norms across many – if not all – domains. And so, we might expect too that a conciliatory response to the disagreement would require the pair to revise a great many of their beliefs.

Of course, as per the ceteris paribus clause on Total Revision, these sceptical consequences may be mitigated if Tessa and Connie have support for any of the relevant beliefs that is grounded in some other undisputed norm. Here, though, it is worth reiterating that the norms in question are both general and fundamental (just as is the practice of inference to the best explanation that they in some sense specify). And, I would suggest, the more general and fundamental a norm is, the less likely it is that any belief formed via following that norm will be well-supported by some other (undisputed) norm. If that is correct, then, whilst some of the beliefs Tessa and Connie have formed via their rival norms may be safe from the sceptical consequences of Total Revision, the majority will not. And, again, since we would expect there to be swathes of disagreement between followers of the two norms, we would still expect the sceptical consequences of a conciliatory response to be great.

I make these points here since much of the discussion in the literature on deep disagreement has focused on cases such as conspiracy. As we saw in section 1, common examples include disagreements between practitioners of alternative and conventional medicine, those who follow scientific principles of inquiry and those who follow the authority of religious texts, people on opposite sides of the conservative/progressive political divide, and so on. All these, though, are examples in which we might expect the rival norms to be general in scope and cover a range of issues broad enough that any sceptical consequences of the disagreement will be comprehensive – if not global.Footnote ⁸ An additional feature that is common to these cases, including conspiracy – and one that I think stems from just the kinds of sceptical worries at issue – is that intuitively at least one of those party to such cases ought to stay steadfast both in norms and in beliefs.Footnote ⁹ Indeed, amongst those who discuss the normative implications of deep disagreement, steadfastness is the more popular choice. So, for instance, Ranalli writes:

Kappel writes:

It is important to reiterate that Ranalli and Kappel (and Matheson) are focusing on cases such as conspiracy where the disagreement involves norms that are general in scope. By focusing primarily on such cases, however, there is a danger that we are too easily tempted into endorsing, not just the steadfast response in the particular case, but a uniform-steadfast account of deep disagreement. Too readily giving into that temptation, I think, would be a mistake. For, the differences between those party to deep disagreement are not always so extreme as in conspiracy or the various other examples listed. Indeed, it strikes me that some of the most interesting examples of deep disagreement will be ones in which the disputants are in many ways, so to speak, following the same rulebook, yet are embroiled in deep disagreement nonetheless. In these cases, it is far less clear that either side to the dispute should stay steadfast. Nonetheless, such disagreements can be just as intractable and resolving them just as problematic as the cases typically discussed. To illustrate these thoughts, consider the following case:

In doctors, Empany and Evitt disagree about the truth of a narrow set of propositions, i.e., ‘treatment-A is best’ and ‘treatment-B is best’. However, the disagreement is not explained by their having different evidence, referring to different guidelines, or by any personal performance error when assessing the relevant evidence. Instead, the roots of the disagreement lie in the weight each gave to their empathy with the patient's expressions of concern about treatment-B. What is more, in doing so, each followed the general understanding of how medical beliefs ought to be formed into which they had been inculcated during their medical training. In this respect, I would suggest, the difference in how the pair came to their beliefs can be characterised in terms of epistemic norms.

So, we might say, Empany follows the norm:

Evitt follows the norm:

Since it is the difference in these norms that explains the disagreement, similarly to conspiracy, doctors counts as a deep disagreement as defined. Unlike conspiracy, however, Empany's and Evitt's norms do not prescribe how one ought to or ought not to form beliefs in all circumstances – but only when deliberating on the truth of propositions that fall within the medical domain. In this respect, we might say that this is a domain specific deep disagreement. Reflecting that, to leverage a concept from the wider literature, we might note also that the pair should think of each other as epistemic peers – at least that is independently of the difference in their norms. Where, as it is most commonly described, disputants are peers when there is rough symmetry in (i) their access to and familiarity with the relevant evidence and (ii) factors that affect how competent they are at processing that evidence. These include, for instance, the possession of relevant virtues and cognitive abilities and circumstantial factors that might impair or enhance disputants’ ability to process the evidence in the particular context (see, for instance: Christensen Reference Christensen2009; Kelly Reference Kelly, Feldman and Warfield2010; Lackey Reference Lackey, Haddock, Millar and Pritchard2010; Matheson Reference Matheson2015).

Why think that Empany and Evitt should think of each other as peers in this way? For one thing, Empany and Evitt have equal access to and familiarity with both the clinical and scientific evidence and the information gained by empathising with their patient. For another, there are no circumstantial factors that might enhance or impair either of their ability to process this evidence. Moreover, both are aware of these features of the case. Thus, the question of whether the pair should think of each other as peers is the question of whether they have evidence that they are similarly competent in a more general sense. There are two reasons for thinking they will have such evidence – moreover there are two reasons for thinking that each will have such evidence by the light of their own norms:

Firstly, though allowing space for evidence-from-empathy, Empany's norm still mandates that one place significant weight on the clinical and scientific evidence. Secondly, and more significantly, for Empany to competently follow her norm, she will have had to have honed her judgement of the import of evidence-from-empathy through medical training and practice. More specifically, she will have honed it – even if not explicitly – against standards and norms operative in the medical community. These will include the standards explicitly formulated in medical guidelines, as well as those explicitly or implicitly instantiated in the practice of other qualified medical professionals, including someone such as Evitt. Given this, though, one would not expect a competent follower of Empany's norm to disagree widely with a competent follower of Evitt's norm. If that is so, however, then given their similar experience and competence, we would also expect Empany and Evitt's track records to provide considerable evidence that both of the pair are competent by the lights of either Empany's or Evitt's norm. Presuming that the pair have some access to such evidence, then, and in the absence of some other difference-making feature, the pair should think of each other as epistemic peers in the way described.

What is the significance of the differences between the two cases?

For one thing, a conciliatory response to a domain specific deep disagreement – even granting the principle of Total Revision – would not have as comprehensive sceptical consequences as in a case such as conspiracy. The anti-sceptical motivation for a uniform steadfast view of deep disagreement stems from the thought that, if all cases of deep disagreement are like conspiracy, then, given the sceptical consequences of conciliating in such cases, allowing that all deep disagreements require a conciliatory response would be to cede the mountain to the sceptic. However, the possibility of domain-specific deep disagreements undercuts this anti-sceptical motivation. Granted the consequences of conciliating for, say, Empany and Evitt would still be extensive – but they would not be so-near global. Thus, we might allow the possibility that the conciliatory response is appropriate in some cases without such concessions to the sceptic as would be were conciliation always the appropriate response.

For another thing, the possibility that the relevant norms of those party to a deep disagreement might be sufficiently close that they should view each other as peers undercuts the intuition fuelled by cases such as conspiracy that at least one party to the disagreement ought not to harbour any doubts about their practices. In cases such as conspiracy, it is appealing to think that someone in Tessa's position should not doubt her practices for the reason that, by her lights, Connie is unlikely to seem in any way a competent agent. But such intuitions do not hold up in a case such as doctors. As noted, in this case, despite their conducting their medical practices according to conflicting epistemic norms, there is reason to think that each party will have significant evidence that the other is in fact competent. But that being so, the intuition that, say, Empany ought not to question herself in respect to the practices by which she came to believe ‘treatment-A is best’, simply because Evitt follows different norms, has far less traction than the parallel intuition re Tessa in conspiracy.

In light of these differences, then, we are faced with the following question: Is it possible that the appropriate response for Tessa in conspiracy is to be steadfast, whilst Empany and Evitt in doctors ought to be conciliatory? We might refer to this question as the ‘Normative Problem of Deep Disagreement’. To resolve it, I suggest, we need to look to the defining characteristic of deep disagreements: i.e., that they are explained by the disputants following rival epistemic norms. More specifically, we need to consider (i) how we come to have the norms we do and (ii) how we implement those norms once we have them. Or, to put it more simply, we need to consider the question of what it means to follow an epistemic norm. I turn to this question in the next section.

Before doing so, it is worth considering whether we already have an explanation of how the appropriate response to disagreement for Empany and Evitt could differ from the appropriate response for Tessa. That is, the norms in doctors are domain-specific, whilst those in conspiracy are not. And, connected to that, Empany and Evitt should think of each other as epistemic peers, whereas Tessa is under no such pressure to think of Connie as her peer. This seems correct.Footnote ¹² As it stands, though, this difference in the two cases offers only a partial explanation of why the appropriate response to the disagreement for Empany and Evitt will differ from that for Tessa. For one thing, it remains an issue of debate within the literature as to whether conciliationism, steadfastness, or some non-uniform view is the correct account of peer disagreement.Footnote ¹³ And, if questions about the significance of peer disagreement more generally remain unsettled, we cannot only appeal to the fact that Empany and Evitt are peers to explain how they should respond to their disagreement – one way or the other. For another, the discussion of peer disagreement has largely focused on cases of ordinary disagreement between individuals. That being so, however, then even if the question of peer disagreement were settled in ordinary cases, we cannot straightforwardly presume that whatever is the correct account of ordinary disagreement will apply to cases of deep disagreement. If, then, we want a full explanation of why the appropriate response for Empany and Evitt should differ from the appropriate response for Tessa to hers, we want also an account of why and how the difference between the two cases re attributions of peerhood is significant in the specific context of deep disagreement. It is in the service of providing just such an explanation that I suggest we need to consider the question of what it means to follow an epistemic norm. So, let's do that.Footnote ¹⁴

3. Epistemic Norms as Social Practices

In the first half of the paper, I suggested that we can usefully characterise deep disagreements as disagreements that occur when disputants have come to hold conflicting beliefs via their following different epistemic norms. In relation to that, I suggested that whatever is the correct response to any case of deep disagreement will turn upon what it means to follow an epistemic norm. What I want to suggest in this section is that to follow an epistemic norm is to somehow regulate one's beliefs in accordance with one's norms. Where, for most of us at least, the regulation of beliefs in accordance with epistemic norms can be explained by one's having been inculcated into normatively loaded ways of perceiving the world via exposure to the epistemic practices of the communities, and members of the communities, of which we are a part. And, once so inculcated, trusting oneself in respect to the reliability of those ways of perceiving the world. We might call this the ‘inculturation and self-trust’ model of norm following. As we shall see later, what it means to have the kind of self-trust described is directly relevant to the normative problem of deep disagreement.

Precedent for this ‘inculturation and trust’ model can be found in a wide range of literature. This includes McDowell's (Reference McDowell1978, Reference McDowell1979) work on moral virtue, Fricker's (Reference Fricker2007) work on testimony and epistemic injustice, accounts of trust and self-trust from Faulkner (Reference Faulkner2011) and Jones (Reference Jones2012a, Reference Jones2012b), and Sripada and Stich's (Reference Sripada, Stich, Carruthers, Laurence and Stich2012) work on the psychology of social and moral norms. Given the breadth of this literature, I shall not endeavour to lay out a systematic account of this understanding of norms and norm acquisition. Rather, I draw on the aforementioned work to explore the features of norms and norm-following that I take to have significance when it comes to discussion of the normative significance of deep disagreement.

4. Responding to Deep Disagreement

In this section, I return to the normative problem of deep disagreement. In section 1, I suggested that deep disagreements can be characterised as disagreements that are explained by the disputants following different epistemic norms. In section 3, I suggested that it is apt to describe the way in which we (typically) come to follow and implement our epistemic norms as the manifestation of a certain kind of socially grounded epistemic self-trust. (Since this is a mouthful, from here on I'll talk more simply of trusting one's norms) Taken together, then, the normative problem of deep disagreement amounts to whether and when it is permissible in the context of deep disagreement to maintain trust in one's norms.

As per discussion in section 1, many deep disagreements will be such that the disputants are not in a position to recognise that their disagreement is deep. Call these opaque deep disagreements. Opaque deep disagreements are a relatively simple affair. If disputants are not in a position to recognise that the disagreement is explained by a difference in norms and they would be permitted to trust their norms outside of the context of disagreement, it is not the case that they ought to doubt themselves in respect to those norms in that context. Rather than questioning themselves in respect to their norms, then, they should look for a more ordinary explanation of the disagreement – e.g., differences in evidence, or a performance error on one of their parts – and they should respond as is appropriate for what they find. In other words, questions about how disputants ought to respond to opaque deep disagreements will be settled by whatever is the correct account of ordinary disagreement and what that account prescribes in the relevant circumstances.Footnote ¹⁸

Whilst many deep disagreements will be opaque, in at least some cases we would expect the disputants to recognise the nature of their disagreement. Call such disagreements transparent deep disagreements. In principle, there is no reason that either domain-specific or disagreements involving more general norms cannot be transparent – this includes cases such as conspiracy and doctors.Footnote ¹⁹ That being so, we still need an explanation of how disputants ought to respond to transparent deep disagreement. More specifically, as per the normative problem of deep disagreement, we need an explanation which allows that, were each disagreement transparent, it would be permissible for Tessa in conspiracy to remain steadfast, whilst Empany and Evitt in doctors ought to be conciliatory.

What I want to suggest, then, is that this is a matter of whether it is reasonable to expect one to see one's rival's norms as a genuine epistemic alternative to one's own. This, in turn, is a matter of whether one has a sufficiently rich stock of shared social epistemic experiences with followers of one's rival's norms of the kind that typically undergird the internalisation of epistemic norms and coming to trust those norms. If one does, then, one ought to doubt one's norms. As such, one ought not to continue trusting oneself in respect to those norms. Thus, one ought to be conciliatory in the face of the disagreement. If one does not have such resources, then, it is not reasonable to expect one to see one's rival's norms as a genuine epistemic alternative to one's own and so the disagreement does not give one reason to doubt one's own norms – even if the disagreement is transparent. That being so, it will be permissible to maintain trust in one's norms and so steadfastness will be appropriate.Footnote ²⁰

Let's cash this out. First, I'll discuss what it is to see one's norms as a genuine epistemic alternative to one's own. Second, I'll discuss the conditions under which it is reasonable to expect one to see one's rival norms as a genuine alternative to one's own. Third, I will put this discussion into contact with our two examples.

As per the account given earlier, following epistemic norms is ordinarily a matter of being inculcated into a normatively loaded way of perceiving the world and trusting one's perceptions of the world to reliably track the application conditions and prescriptions of those norms. What I want to suggest here is that to see one's rival's epistemic norms as a genuine epistemic alternative to one's own is a matter of being able to imagine perceiving the world in just this way whilst following that person's norms. We might think of this as one's being able to manifest a kind of virtual self-trust that is grounded in one's ability to imaginatively inhabit a way of perceiving the world different from one's own. The greater the difference in norms the greater the leap of imagination required. This kind of imaginative act may be aided by the disputants reflecting upon the evidence they have that a disagreement is deep – but such intellectual consideration will not suffice to make the leap wholesale. Rather, much as I have suggested we typically come to internalise our own norms through exposure to the practices of others, this kind of leap would typically require an agent to have a rich stock of shared social-epistemic experiences with followers of the rival norm on which to draw. These are the kinds of experience that involve the recognition of epistemic authority, relationships of dependence and trust, and epistemic cooperation and collaboration; i.e., just the kind of resources that will typically ground an agent's coming to follow and trust in their own epistemic norms.

Importantly, whilst this kind of imaginative act involves being able to reliably track the application conditions and prescriptions of one's rival's norms, it does not consist of that alone. What is crucial is that one be able to do so in the manner of trusting norms. This is important since there are ways of tracking one's rival's norms other than the kind of imaginative act described above. Most obviously, one could simply pay attention to what one's rival believes and in what conditions they believe as they do. Merely tracking the prescriptions of competing norms – this way or another – is not, however, enough to afford one reason to doubt one's own norms. This is because knowing what a norm prescribes is not reason to think that those prescriptions should be followed or that the corresponding norms are candidates for being good norms. In contrast, when one comes to see one's rival's norms as a genuine epistemic alternative to one's own in the way described, one grasps – not only what the prescriptions of those norms are – but what it would be like to be normatively compelled to comply with those prescriptions. Thus, mimicking the way one develops a genuinely normative and epistemic sensibility re one's own norms as described in section 3. And, it is this grasping of how the prescriptions of one's rivals norms could be normatively compelling – just as are the prescriptions of one's own – in respect to which it can be appropriate to doubt oneself in respect to one's own norms.Footnote ²¹

This brings us, then, to the question of when is it reasonable to expect one to see one's rival's norms as a genuine epistemic alternative to one's own – i.e. as per above, when the realisation that a disagreement is deep will afford one reason to doubt one's own norms. My suggestion here is that it will be reasonable to expect this just when one shares the kind of social-epistemic experiences and interactions with followers of one's rival's norms that would ordinarily facilitate a competent follower of one's own norms in manifesting the virtual self-trust in one's rival's norms described above. If one does have such resources, then, it is reasonable to expect one to see one's rival's norms as a genuine epistemic alternative to one's own – in which case, I suggest, realisation of the disagreement will afford one reason to doubt one's own norms. If one does not have such resources, then, it is not reasonable to expect one to see one's rival's norms as a genuine epistemic alternative to one's own – in which case, I suggest, realisation of the disagreement will not afford one reason to doubt one's own norms.

(It is worth noting that reasonable expectations so understood correspond to what the ordinary competent follower of one's norms is in a position to do. We could imagine agents who are, respectively, particularly gifted or particularly incompetent when it comes to the kind of imaginative act described. I presume, though, that it is neither reasonable to expect disputants to be particularly gifted, nor that incompetence gives one a free pass when it comes to epistemic oughts.)

With this account in hand we can return to the question of how it can be permissible for Tessa in conspiracy to remain steadfast, yet Empany and Evitt in doctors ought to be conciliatory.

Take conspiracy. In this case, the social dimensions of deep disagreement have a kind of inverted significance in respect to the rational status of Tessa's continued trust in her norms. That is to say that, given that the difference in norms is fundamental and wide, we would not expect Tessa and Connie to share the social-epistemic experiences and interactions that would ordinarily facilitate a competent follower of Tessa's norm's coming to see Connie's norms as a genuine epistemic alternative to her own. And, if that is so, on the account given here, it will not be reasonable to expect of Tessa that she see Connie's norms in this way. Thus, the realisation that the disagreement is deep will fail to undermine the rational status of her continued self-trust. Thus, even if the disagreement is transparent, Tessa can rationally respond in steadfast fashion.

As noted in section 2, the kinds of deep disagreement which threaten global scepticism tend to be of a kind with conspiracy. Thus, the thought that it can be rational to maintain trust in one's norms even in cases where the difference in norms is transparent allows us to stave off the sceptical worries that are associated with these kinds of case.

The flip side to this suggestion is that the possibility that those party to transparent deep disagreement will be permitted to stay steadfast in a narrower, domain-specific case of deep disagreement such as doctors will be comparatively lower. After all, as we saw in section 2, the contents of the rival's norms in this case are such that we would not expect followers of each to doubt each other's competence as a matter of course. Correspondingly, there is no reason to think that they would not have the rich stock of shared social experiences that might spur the imaginative leap to understanding the other's epistemic sensibilities that is required to see the other's norms as representing a genuine alternative to their own. If Empany and Evitt do have such resources, though, it is reasonable to expect them to see each other's norms as a genuine alternative to their own. In which case, they ought to doubt their norms. As such, the pair ought to respond to the realisation of the nature of the disagreement in conciliatory fashion. As noted earlier, such a response will still have revisionary consequences – though not the comprehensive and wide-ranging ones associated with cases such as conspiracy. Again, though, this seems to match up well with the intuitions that led us to consider such cases to start with and to consider whether a non-uniform approach to deep disagreement may be the correct approach to deep disagreement.

5. Comments and Clarifications

Before wrapping up, I shall briefly discuss two areas worth additional clarification.Footnote ²²