Defeat

In some cases of higher-order defeat, you rationally doubt whether your credence in p is rational without having evidence of how to improve your credence in p. According to the resilience framework proposed by Steglich-Petersen (Higher-order defeat and Doxastic Resilience), such cases require loss of doxastic resilience: retain your credence level but become more disposed to change your mind given future evidence. Henderson (Higher-Order Evidence and Losing One’s Conviction) responds that this allows for irrational decision-making and that we are better (...) off understanding higher-order defeat in terms of imprecise probabilities. We argue first that Henderson’s imprecise probability framework models the wrong kind of thing. Credal imprecision is neither necessary nor sufficient for higher-order doubt. Second, we offer two ways of understanding the practical import of higher-order defeat given loss of doxastic resilience. (shrink)

I argue that one ought not be epistemically akratic. Although this position may look self-evident, it is hard to pin down exactly what’s wrong with the akratic subject. Indeed, some philosophers argue that epistemic akrasia is permissible. The standard anti-akratic response focuses on the weird downstream implications of this state for action and assertion. This approach, however, is unsatisfactory, since it fails to explain the epistemic impermissibility of epistemic akrasia. Here, I argue that epistemic akrasia is impermissible on a purely (...) epistemic basis. Doing so brings out the connection between positive epistemic statuses and truth: it is that connection that explains the fundamental impermissibility of epistemic akrasia. (shrink)

Among those who think that emotions can provide epistemic reasons for belief, there is disagreement about whether emotions provide foundational reasons (ones that are not based on further reasons) or non-foundational reasons (ones that are based on further reasons). I argue in this paper that considerations about evidence of emotional unreliability favour the non-foundational view of emotional reasons. The argument starts with a set of counterexamples to the claim that evidence of emotional unreliability always defeats emotional justification. I then show (...) why only the non-foundational picture of emotional reasons is compatible with this finding. The upshot is 2-fold: first, the commonly held assumption that evidence of emotional unreliability always defeats emotional justification is false; and, second, this gives us a reason for preferring a non-foundational picture of emotional reasons. (shrink)

In this paper I examine a recent incarnation of common objection to evidentialism. According to this common objection, evidentialism gives the wrong verdicts in cases where the subject has been irresponsible in inquiry. Sandy Goldberg (2021) has argued that a particularly vivid instance of this problem occurs when an individual violates normative expectations that have been placed on them in their inquiry. Having laid out Goldberg’s case, I argue that the desirable verdicts can be better attained by endorsing evidentialism and (...) supplementing it with an account of robust justification that I have defended elsewhere. (shrink)

I will present a novel argument that there can be epistemically vicious knowledge. In the kind of case that interests me, the subject knows not despite but rather because of her vice. It is generally agreed that some kinds of epistemic luck doesn’t undermine knowledge. For instance, being lucky not to have misleading evidence doesn’t undermine knowledge. I will argue that this doesn’t change when the avoidance of misleading evidence depends on the subject’s vice. It does not prevent her belief (...) from being both safe and sensitive, nor does it have any bearing on whether her justifying reasons are ultimately defeated. To illustrate my point, I will draw a parallel with a certain way of thinking about resultant moral luck. I will then go on to consider the ramifications for virtue-theoretic analyses of knowledge and the doctrine of normative defeat. (shrink)

This paper does four things. First it lays out an orthodox position on reasons and defeaters. Then it argues that the position just laid out is mistaken about “undercutting” defeaters. Then the paper explains an unpublished thought experiment by Dorothy Edgington. And then it uses that thought experiment to motivate a new approach to undercutting defeaters.

This entry explains what the issue of weighing reasons is about and then discusses a number of theories concerning weighing reasons. The general issue concerns how reasons (or considerations or pros and cons) systematically interact to determine the normative status of some action, belief, or attitude. For example, it concerns how reasons determine whether an action is permissible, required, or what ought to be done. The general issue also concerns how reasons aggregate or themselves result from systematic interactions with the (...) broader context. Along the way, the entry considers whether reasons can be incommensurable (e.g., be on a par); whether reasons have more than one weight value (e.g., justifying, requiring, and commending); the relation between reasons for and reasons against; conditions (enablers, disablers); modifiers (amplifiers, attenuators); exclusionary reasons; higher order evidence; what happens when, say, morality and epistemic rationality conflict; and so on. (shrink)

Rational or epistemically justified beliefs are often said to be defeasible. That is, beliefs that have some otherwise justification conferring property can lose their epistemic status because they are defeated by some evidence possessed by the believer or due to some external facts about the believer’s epistemic environment. Accordingly, many have argued that we need to add a so-called no defeater clause to any theory of epistemic justification. In this paper, I will survey various possible evidentialist as well as responsibilitst (...) no-defeater clauses and develop a general taxonomy of defeater cases against which these clauses can be tested. Despite influential arguments that evidentialist understandings of justification are ill-equipped to handle the full spectrum of defeater cases, I will demonstrate that evidentialism has the right tools to make sense of all kinds of defeaters, including propositional and normative defeaters. Moreover, I will demonstrate that the proposed solution avoids recently influential objections against the notion of defeat. (shrink)

According to the Doctrine of Normative Defeat (‘the DND’), you may lose justification to believe that p if you fail to possess negatively relevant evidence that you ought to possess. This paper presents an objection to the DND as it’s standardly developed: it carries with it an absurd implication regarding how one’s knowledge can be restored once one’s associated epistemic justification is presumed to be normatively defeated. I defend the force of this objection before closing with a note about what (...) my argument means for the DND's motivation. (shrink)

In the contemporary epistemological literature, peer disagreement is often taken to be an instance of a more general phenomenon of “higher-order evidence.” Correspondingly, its epistemic significance is often thought to turn on the epistemic significance of higher-order evidence in general. This chapter attempts to evaluate this claim, and in doing so to clarify some points of unclarity in the current literature – both about what it is for evidence to be “higher-order,” and about the relationship between disagreement and higher-order evidence. (...) We will begin by considering some candidate definitions of “higher-order evidence,” and offering our own definition that attempts to capture the phenomenon of interest. We will then consider, in light of this definition, whether disagreement and its epistemic significance are best-understood as a kind of higher-order evidence. We’ll argue that although peer disagreement can be epistemically significant qua higher-order evidence, this role doesn’t exhaust its significance, and that it can also serve as straightforward first-order evidence. Finally, we’ll suggest that inattention to this latter point has made broadly conciliatory views about peer disagreement seem somewhat easier to resist than they in fact are. (shrink)

Conciliationism is the family of views that rationality requires agents to reduce confidence or suspend belief in p when acknowledged epistemic peers (i.e. agents who are (approximately) equally well-informed and intellectually capable) disagree about p. While Conciliationism is prima facie plausible, some have argued that Conciliationism is not an adequate theory of peer disagreement because it is self-undermining. Responses to this challenge can be put into two mutually exclusive and exhaustive groups: the Solution Responses which deny Conciliationism is self-undermining and (...) attempt to provide arguments which demonstrate this; and the Skeptical Responses which accept that Conciliationism is self-undermining but attempt to mitigate this result by arguing this is either impermanent and/or not very worrisome. I argue that, by Conciliationism’s own lights, both kinds of responses (almost certainly) fail to save Conciliationism from being self-undermining. Thus, Conciliationism is (almost certainly) permanently self-undermining. This result is significant because it demonstrates that Conciliationism is likely hopeless: there is likely nothing that can save Conciliationism from this challenge. I further argue that Conciliationism, like any view, should be abandoned if it is (almost certainly) hopeless. (shrink)

Drawing on the puzzling behavior of ordinary knowledge ascriptions that embed an epistemic (im)possibility claim, we tentatively conclude that it is untenable to jointly endorse (i) an unfettered classical logic for epistemic language, (ii) the general veridicality of knowledge ascription, and (iii) an intuitive ‘negative transparency’ thesis that reduces knowledge of a simple negated ‘might’ claim to an epistemic claim without modal content. We motivate a strategic trade-off: preserve veridicality and (generalized) negative transparency, while abandoning the general validity of contraposition. (...) We criticize various approaches to incorporating veridicality into domain semantics, a paradigmatic ‘information-sensitive’ framework for capturing negative transparency and, more generally, the non-classical behavior of sentences with epistemic modals. We then present a novel information-sensitive semantics that successfully executes our favored strategy: stable acceptance semantics, extending a vanilla bilateral state-based semantics for epistemic modals with a knowledge operator loosely inspired by the defeasibility theory of knowledge. (shrink)

In Appearance and Explanation, McCain and Moretti raise three objections to Phenomenal Conservatism: the problem of explaining defeaters, the problem of reflective awareness, and the bootstrapping problem. I address all three problems and then raise three objections to Phenomenal Explanationism: the problem of necessary truths, the problem of unreflective observers, and the problem of excessive flexibility. I conclude that there is no need to supplement Phenomenal Conservatism with Explanationism.

The child objection is a major challenge for reductionism, which requires hearers to have positive reasons for testimonial justification. However, it has been pointed out that anti-reductionism, which requires only the absence of negative reasons, or defeaters, suffers from the same kind of problem. The child objection presupposes the empirical thesis that “children do not have the capacity to consider reasons,” but the plausibility of this assumption may be revealed by developmental psychology research on selective trust. This paper uses recent (...) epistemological studies as a guide to narrow down the types of defeaters that children are required to consider, and then clarifies what kind of reasons various experiments can be said to test the ability to consider, and in what sense children who pass the test can be said to be “considering” reasons. In doing so, we clarify the scope and limits of the implications that selective trust studies can have for reductionism and anti-reductionism. We then suggest what future psychological research is desired from an epistemological interest to go beyond the current limitations. (shrink)

The paper proposes an account of the rational response to higher‐order evidence whose key claim is that whenever we acquire such evidence we ought to engage in the inquiring activity of double‐checking. Combined with a principle that establishes a connection between rational inquiry and rational belief retention, the account offers a novel explanation of the alleged impermissibility of retaining one's belief in the face of higher‐order evidence. It is argued that this explanation is superior to the main competitor view which (...) appeals to the notion of defeat. (shrink)

In this paper, I will present a problem for reductive accounts of knowledge-undermining epistemic luck. By “reductive” I mean accounts that try to analyze epistemic luck in non-epistemic terms. I will begin by briefly considering Jennifer Lackey's (2006) criticism of Duncan Pritchard's (2005) safety-based account of epistemic luck. I will further develop her objection to Pritchard by drawing on the defeasible-reasoning tradition. I will then show that her objection to safety-based accounts is an instance of a more general problem with (...) reductive accounts of epistemic luck. In short, they face a dilemma: they can either fail to vindicate the intuitive verdicts about cases or they can illicitly appeal to the epistemic vocabulary they are trying to reduce. The upshot is that we can only understand epistemic luck in terms of the assessment of the subject's reasons and we can't give a reductive account of that. (shrink)

In this paper I investigate whether there are any cases in which it is rational for a person to hold inconsistent beliefs and, if there are, just what implications this might have for the theory of epistemic justification. A number of issues will crop up along the way – including the relation between justification and rationality, the nature of defeat, the possibility of epistemic dilemmas, the importance of positive epistemic duties, and the distinction between transitional and terminal attitudes.

When and why does awareness of a belief's genealogy render it irrational to continue holding that belief? According to explanationism, awareness of a belief’s genealogy gives rise to an epistemic defeater when and because it reveals that the belief is not explanatorily connected to the relevant worldly facts. I argue that an influential recent version of explanationism, due to Korman and Locke, incorrectly implies that it is not rationally permissible to adopt a “sparse” ontology of worldly facts or states of (...) affairs. I then propose a new explanationist account of genealogical defeat capable of accommodating rational belief in ontological sparsity. According to my account, awareness of a belief’s genealogy gives rise to a defeater when and because it reveals that the belief is not explanatorily connected to its truthmaker. (shrink)

This chapter presents a typology of the different kinds of inductive inferences we can draw from our evidence, based on the explanatory relationship between evidence and conclusion. Drawing on the literature on graphical models of explanation, I divide inductive inferences into (a) downwards inferences, which proceed from cause to effect, (b) upwards inferences, which proceed from effect to cause, and (c) sideways inferences, which proceed first from effect to cause and then from that cause to an additional effect. I further (...) distinguish between direct and indirect forms of downwards and upwards inferences. I then show how we can subsume canonical forms of inductive inference mentioned in the literature, such as inference to the best explanation, enumerative induction, and analogical inference, under this typology. Along the way, I explore connections with probability and confirmation, epistemic defeat, the relation between abduction and enumerative induction, the compatibility of IBE and Bayesianism, and theories of epistemic justification. (shrink)

We offer a general framework for theorizing about the structure of knowledge and belief in terms of the comparative normality of situations compatible with one’s evidence. The guiding idea is that, if a possibility is sufficiently less normal than one’s actual situation, then one can know that that possibility does not obtain. This explains how people can have inductive knowledge that goes beyond what is strictly entailed by their evidence. We motivate the framework by showing how it illuminates knowledge about (...) the future, knowledge of lawful regularities, knowledge about parameters measured using imperfect instruments, the connection between knowledge, belief, and probability, and the dynamics of knowledge and belief in response to new evidence. (shrink)

Knowledge defeat occurs when a subject knows that _p_, gains a defeater for her belief, and thereby loses her knowledge without necessarily losing her belief. It’s far from obvious that externalists can accommodate putative cases of knowledge defeat since a belief that satisfies the externalist conditions for knowledge can satisfy those conditions even if the subject later gains a defeater for her belief. I’ll argue that virtue reliabilists can accommodate defeat intuitions via a new kind of error theory. I argue (...) that in cases where the subject holds dogmatically onto her belief in the face of an apparent defeater, her belief never qualified as knowledge, since the belief was not gained via an exercise of her epistemic virtues. In cases where the subject suspends her judgment upon receiving the putative defeater her original belief might have qualified as knowledge, but crucially, in such cases knowledge is lost due to loss of belief, rather than due to the epistemic force of the defeater. Therefore, knowledge defeat isn’t a genuine phenomenon even though there are no cases where a subject knows what she originally believed after receiving the putative defeater. (shrink)

How, if at all, is knowing how to do something defeasible? Some, the “intellectualists”, treat the defeasibility of knowledge-how as in some way derivative on the defeasibility of knowledge-that. According to a recent proposal by Carter and Navarro (Philos Phenomenol Res 3:662–685, 2017), knowledge-how defeat cannot be explained in terms of knowledge-that defeat; instead, knowledge-how defeat merits and entirely separate treatment. The thought behind “separatism” is easy to articulate. Assuming that knowledge of any kind is defeasible, since knowledge-that and knowledge-how (...) are fundamentally different beasts, the best accounts of their defeasibility must reflect the underlying differences between them. I reject a separatist treatment of the defeasibility of knowledge-that and knowledge-how. One can acknowledge certain important differences between knowledge-that and knowledge-how without thereby needing two theories of defeasibility. Ultimately, though, I’ll argue that the defeasibility of basic knowledge-how, unlike non-basic knowledge-how, is a much more difficult issue than has been acknowledged. (shrink)

Sometimes, learning about the origins of a belief can make it irrational to continue to hold that belief—a phenomenon we call ‘genealogical defeat’. According to explanationist accounts, genealogical defeat occurs when one learns that there is no appropriate explanatory connection between one’s belief and the truth. Flatfooted versions of explanationism have been widely and rightly rejected on the grounds that they would disallow beliefs about the future and other inductively-formed beliefs. After motivating the need for some explanationist account, we raise (...) some problems for recent versions of explanationism. Learning from their failures, we then produce and defend a more resilient explanationism. (shrink)

According to principles of modal security, evidence undermines a belief only when it calls into question certain purportedly important modal connections between one’s beliefs and the truth (e.g., safety or sensitivity). Justin Clarke-Doane and Dan Baras have advanced such principles with the aim of blocking evolutionary moral debunking arguments. We examine a variety of different principles of modal security, showing that some of these are too strong, failing to accommodate clear cases of undermining, while others are too weak, failing to (...) do their advertised work of blocking evolutionary moral debunking arguments. If there is a security principle that slips between the horns of this dilemma—one that is both viable and debunker-blocking—it remains to be formulated. (shrink)

Matthew McGrath has recently challenged all theories that allow for immediate perceptual justification. This challenge comes by way of arguing for what he calls the “Looks View” of visual justification, which entails that our visual beliefs that are allegedly immediately justified are in fact mediately justified based on our independent beliefs about the looks of things. This paper shows that McGrath’s arguments are unsound or, at the very least, that they do not cause genuine concern for the species of dogmatism (...) called “Phenomenal Explanationism”, recently introduced and defended by Kevin McCain and Luca Moretti. (shrink)

One emerging issue in contemporary epistemology concerns the relation between animal knowledge, which can be had by agents unable to take a view on the epistemic status of their attitudes, and reflective knowledge, which is only available to agents capable of taking such a view. Philosophers who are open to animal knowledge often presume that while many of the beliefs of human adults are formed unreflectively and thus constitute mere animal knowledge, some of them—those which become subject of explicit scrutiny (...) or are the result of a deliberative effort—may attain the status of reflective knowledge. According to Sanford Goldberg and Jonathan Matheson (2020), however, it is impossible for reflective subjects to have mere animal knowledge. If correct, their view would have a number of repercussions, perhaps most notably the vindication of a dualism about knowledge, which would frustrate attempts to provide a unified account of knowledge-attributions to human adults, very young children, and non-human animals. I discuss Goldberg and Matheson’s proposal, outline some of the ways in which it is insightful, and argue that it is ultimately unsuccessful because it neglects the inherent temporal dimension of knowledge acquisition. While the article is pitched as a reply to Goldberg and Matheson, its primary aim is to highlight significant connections between the debates on the relation between animal and reflective knowledge, propositional and doxastic justification, and the theory of epistemic defeat. (shrink)

This chapter explores global debunking arguments, debunking arguments that aim to give one a global defeater. I defend Alvin Plantinga’s view that global defeaters are possible and, once gained, are impossible to escape by reasoning. They thereby must be extinguished by other means: epistemically propitious actions, luck, or grace. I then distinguish between three types of global defeater—pure-undercutters, undercutters-because-rebutters, and undercutters-while-rebutters—and systematically consider how one can deflect such defeaters. Lastly, since I draw insights from the literature on perhaps the most (...) widely discussed global debunking argument in the literature, Plantinga’s evolutionary argument against naturalism, I end up responding to many potential problems for it. This includes the so-called conditionalization problem, as well as those raised by Bergmann (2002), Law (2012), Deem (2018), Hendricks and Anderson (2020), and Wielenberg (in Craig and Wielenberg (2021)). (shrink)

I will discuss a variety of cases such that the subject's believing truly is somewhat of an accident, but less so than in a Gettier case. In each case, this is because her reasons are not ultimately undefeated full stop, but they are ultimately undefeated with certain qualifications. For example, the subject's reasons might be ultimately defeated considered in themselves but ultimately undefeated considered as a proper part of an inference to the best explanation that is undefeated without qualification. In (...) each section of the paper, I consider different qualifications and show how in each case we get an epistemic standing I call “coach-class knowledge”. First-class knowledge requires justifying reasons that are undefeated without qualification. Coach-class knowledge only requires qualified lack of defeat. I will use this distinction to bring debates over knowledge from falsehood and fake barns to an ecumenical resolution. In both cases, the subject enjoys coach-class rather than first-class knowledge. I will also show that the defeasible reasoning tradition can better account for graded accidental truth than safety theories. (shrink)

Reasons rationalize beliefs. Reasons, when all goes well, turn true beliefs into knowledge. I am interested in the relationship between these aspects of reasons. Without a proper understanding of their relationship, the theory of knowledge will be less illuminating than it ought to be. I hope to show that previous accounts have failed to account for this relationship. This has resulted in a tendency to focus on justification rather than knowledge. It has also resulted in many becoming skeptical about the (...) prospects for an analysis of knowledge. The skepticism is misplaced and the tendency can be fixed without sacrificing any insights. The solution is to see how good reasons (in a sense to be articulated) are apparent (in a sense to be articulated) to the knowing subject. Once this claim is unpacked, we see that it is an illuminating analysis of knowledge in terms of distinct but intimately related aspects of epistemic assessment. It helps us see the value of knowledge (over and above true belief) and it affords us a unified, “reasons-first” metaepistemology. The resulting picture is neither a familiar kind of internalism or externalism. (shrink)

Here I will develop a naturalistic account of epistemic reflection and its significance for epistemology. I will first argue that thought, as opposed to mere information processing, requires a capacity for cognitive self-regulation. After discussing the basic capacities necessary for cognitive self-regulation of any kind, I will consider qualitatively different kinds of thought that can emerge when the basic capacities enable the creature to interiorize a form of social cooperation. First, I will discuss second-personal cooperation and the kind of thought (...) that emerges from its interiorization. Then, I will discuss third-personal cooperation and the kind of thought that emerges from its interiorization. We will see that epistemic reflection is the interiorized version of interpersonal argumentation, which is the epistemic component of third-personal cooperation. In developing this account, I will draw heavily on the work of Michael Tomasello and other cognitive scientists advocating the “social intentionality hypothesis”. However, I will show how work done in the defeasible reasoning tradition can provide us with a deeper explanation of some claims made by advocates of the social intentionality hypothesis. Additionally, we will see that work done on social intentionality can help us better understand the significance of knowledge and justification as understood by the defeasible reasoning tradition. We will see that the social intentionality hypothesis and the defeasible reasoning tradition are mutually illuminating. By drawing equally on both, I will provide a novel account of the foundations of knowledge. (shrink)

Public life abounds with examples of people whose beliefs—especially political beliefs—seem suspiciously convenient: consider, for example, the billionaire who believes that all taxation is unjust, or the Supreme Court Justice whose interpretations of what the law says reliably line up with her personal political convictions. After presenting what I take to be the best argument for the epistemological relevance of suspicious convenience, I diagnose how attempts to resist this argument rest on a kind of epistemological ideal theory, in a sense (...) to be made precise. And I argue that the ways in which this ideal theory can be deployed in defense of suspiciously convenient beliefs brings out the pernicious and distorting nature of such ideal theory in epistemology. (shrink)

Among epistemologists, it is common to assume that insofar as coherence bears on the justification of belief, the only relevant coherence relations are those _within_ an individual subject’s web of beliefs. After clarifying this view and exploring some plausible motivations for it, we argue that this individualistic account of the epistemic relevance of coherence fails to account for central facets of scientific practice. In its place we propose a social account of coherence. According to the view we propose, a scientist (...) _S_’s belief that _p_ is _prima facie_ unjustified if this belief negatively coheres with justified scientific claims in her scientific community. This account of coherence yields an epistemology for scientific belief which, we argue, has all of the benefits and none of the liabilities of its more individualistic predecessor. (shrink)

The recursive aspect of process reliabilism has rarely been examined. The regress puzzle, which illustrates infinite regress arising from the combination of the recursive structure and the no-defeater condition incorporated into it, is a valuable exception. However, this puzzle can be dealt with in the framework of process reliabilism by reconsidering the relationship between the recursion and the no-defeater condition based on the distinction between prima facie and ultima facie justification. Thus, the regress puzzle is not a basis for abandoning (...) process reliabilism. A genuinely intractable problem for recursive reliabilism lies in the gap between the reliability of the entire path to a belief and that of its parts. Confronted with this puzzle, reliabilists can orient themselves toward ‘reliable-as-a-whole reliabilism’ instead of ‘reliable-in-every-part reliabilism’, including recursive reliabilism, which is found to be not well-motivated. (shrink)

In addition to the notion of defeat, do we need to expand the epistemological repertoire used in accounting for the context dependence of justification? It has recently been argued that we ought to admit a hitherto unrecognized fundamental epistemic kind called ‘disqualifiers’. Disqualifiers are taken to be not reducible to any other epistemic notion. Rather, they are meant to be primitive. If this is correct, it is a surprising and novel discovery, and so it is worthy of further epistemological investigation. (...) In this paper I shall first argue that the cases given do not motivate positing the notion of a disqualifier. Conclusions drawn about the existence of disqualifiers do not follow from the considerations advanced. Second, I shall directly argue that an essential core claim of those who would posit disqualifiers, that so-called disqualifiers actually do prevent epistemic bases from conferring justification, is false. In sum, I shall argue that there are no disqualifiers. (shrink)

In the 1980s, Pollock’s work on default reasons started the quest in the AI community for a formal system of defeasible argumentation. The main goal of this paper is to provide a logic of structured defeasible arguments using the language of justification logic. In this logic, we introduce defeasible justification assertions of the type t : F that read as “t is a defeasible reason that justifies F”. Such formulas are then interpreted as arguments and their acceptance semantics is given (...) in analogy to Dung’s abstract argumentation framework semantics. We show that a large subclass of Dung’s frameworks that we call “warranted” frameworks is a special case of our logic in the sense that Dung’s frameworks can be obtained from justification logic-based theories by focusing on a single aspect of attacks among justification logic arguments and Dung’s warranted frameworks always have multiple justification logic instantiations called “realizations”. We first define a new justification logic that relies on operational semantics for default logic. One of the key features that is absent in standard justification logics is the possibility to weigh different epistemic reasons or pieces of evidence that might conflict with one another. To amend this, we develop a semantics for “defeaters”: conflicting reasons forming a basis to doubt the original conclusion or to believe an opposite statement. This enables us to formalize non-monotonic justifications that prompt extension revision already for normal default theories. Then we present our logic as a system for abstract argumentation with structured arguments. The format of conflicting reasons overlaps with the idea of attacks between arguments to the extent that it is possible to define all the standard notions of argumentation framework extensions. Using the definitions of extensions, we establish formal correspondence between Dung’s original argumentation semantics and our operational semantics for default theories. One of the results shows that the notorious attack cycles from abstract argumentation cannot always be realized as justification logic default theories. (shrink)

This paper develops a logical theory that unifies all three standard types of argumentative attack in AI, namely rebutting, undercutting and undermining attacks. We build on default justification logic that already represents undercutting and rebutting attacks, and we add undermining attacks. Intuitively, undermining does not target default inference, as undercutting, or default conclusion, as rebutting, but rather attacks an argument’s premise as a starting point for default reasoning. In default justification logic, reasoning starts from a set of premises, which is (...) then extended by conclusions that hold by default. We argue that modeling undermining defeaters in the view of default theories requires changing the set of premises upon receiving new information. To model changes to premises, we give a dynamic aspect to default justification logic by using the techniques from the logic of belief revision. More specifically, undermining is modeled with belief revision operations that include contracting a set of premises, that is, removing some information from it. The novel combination of default reasoning and belief revision in justification logic enriches both approaches to reasoning under uncertainty. By the end of the paper, we show some important aspects of defeasible argumentation in which our logic compares favorably to structured argumentation frameworks. (shrink)

In this paper I will compare two competing accounts of assertion: the knowledge account and the justified belief account. When it comes to the evidence that is typically used to assess accounts of assertion – including the evidence from lottery propositions, the evidence from Moore’s paradoxical propositions and the evidence from conversational patterns – I will argue that the justified belief account has at least as much explanatory power as its rival. I will argue, finally, that a close look at (...) the ways in which assertions can be challenged and retracted reveals a certain advantage for the justified belief account. The paper will touch upon a number of further topics along the way, including the logical interaction between knowledge and justified belief, the nature of defeat, and the hypothesis that knowledge and justified belief are normatively coincident goals. (shrink)

According to the principle of Conjunction Closure, if one has justification for believing each of a set of propositions, one has justification for believing their conjunction. The lottery and preface paradoxes can both be seen as posing challenges for Closure, but leave open familiar strategies for preserving the principle. While this is all relatively well-trodden ground, a new Closure-challenging paradox has recently emerged, in two somewhat different forms, due to Backes :3773–3787, 2019a) and Praolini :715–726, 2019). This paradox synthesises elements (...) of the lottery and the preface and is designed to close off the familiar Closure-preserving strategies. By appealing to a normic theory of justification, I will defend Closure in the face of this new paradox. Along the way I will draw more general conclusions about justification, normalcy and defeat, which bear upon what Backes :2877–2895, 2019b) has dubbed the ‘easy defeat’ problem for the normic theory. (shrink)

One leading approach to justification comes from the reliabilist tradition, which maintains that a belief is justified provided that it is reliably formed. Another comes from the ‘Reasons First’ tradition, which claims that a belief is justified provided that it is based on reasons that support it. These two approaches are typically developed in isolation from each other; this essay motivates and defends a synthesis. On the view proposed here, justification is understood in terms of an agent’s reasons for belief, (...) which are in turn analyzed along reliabilist lines: an agent's reasons for belief are the states that serve as inputs to their reliable processes. I show that this synthesis allows each tradition to profit from the other's explanatory resources. In particular, it enables reliabilists to explain epistemic defeat without abandoning their naturalistic ambitions. I go on to compare my proposed synthesis with other hybrid versions of reliabilism that have been proposed in the literature. (shrink)

In recent years there has been an explosion of interest in Artificial Intelligence (AI) both in health care and academic philosophy. This has been due mainly to the rise of effective machine learning and deep learning algorithms, together with increases in data collection and processing power, which have made rapid progress in many areas. However, use of this technology has brought with it philosophical issues and practical problems, in particular, epistemic and ethical. In this paper the authors, with backgrounds in (...) philosophy, maternity care practice and clinical research, draw upon and extend a recent framework for shared decision-making (SDM) that identified a duty of care to the client's knowledge as a necessary condition for SDM. This duty entails the responsibility to acknowledge and overcome epistemic defeaters. This framework is applied to the use of AI in maternity care, in particular, the use of machine learning and deep learning technology to attempt to enhance electronic fetal monitoring (EFM). In doing so, various sub-kinds of epistemic defeater, namely, transparent, opaque, underdetermined, and inherited defeaters are taxonomized and discussed. The authors argue that, although effective current or future AI-enhanced EFM may impose an epistemic obligation on the part of clinicians to rely on such systems' predictions or diagnoses as input to SDM, such obligations may be overridden by inherited defeaters, caused by a form of algorithmic bias. The existence of inherited defeaters implies that the duty of care to the client's knowledge extends to any situation in which a clinician (or anyone else) is involved in producing training data for a system that will be used in SDM. Any future AI must be capable of assessing women individually, taking into account a wide range of factors including women's preferences, to provide a holistic range of evidence for clinical decision-making. (shrink)

This volume is about the notion of 'defeat' in philosophy. The idea is that someone who has some knowledge, or a justified belief, can lose this knowledge or justified belief if they acquire a 'defeater' - evidence that undermines it. The contributors examine the role of defeat not just in epistemology but in practical reasoning and ethics.

My aim in this paper is to cast doubt on the idea of undercutting defeat by showing that it is beset by some serious problems. I examine a number of attempts to specify the conditions for undercutting defeat and find them to be defective. Absent further attempts, and on the basis of the considerations offered, I conclude that an adequate notion of undercutting defeat is lacking.

Epistemic defeat is standardly understood in either evidentialist or responsibilist terms. The seminal treatment of defeat is an evidentialist one, due to John Pollock, who famously distinguishes between undercutting and rebutting defeaters. More recently, an orthogonal distinction due to Jennifer Lackey has become widely endorsed, between so-called doxastic (or psychological) and normative defeaters. We think that neither doxastic nor normative defeaters, as Lackey understands them, exist. Both of Lackey’s categories of defeat derive from implausible assumptions about epistemic responsibility. Although Pollock’s (...) evidentialist view is superior, the evidentialism per se can be purged from it, leaving a general structure of defeat that can be incorporated in a reliabilist theory that is neither evidentialist nor responsibilist in any way. (shrink)

Subjects who retain their beliefs in the face of higher-order evidence that those very beliefs are outputs of flawed cognitive processes are at least very often criticisable. Many think that this is because such higher-order evidence defeats various epistemic statuses such as justification and knowledge, but it is notoriously difficult to give an account of such defeat. This paper outlines an alternative explanation, stemming from some of my earlier work, for why subjects are criticisable for retaining beliefs in the face (...) of paradigm kinds of putatively defeating higher-order evidence: they manifest dispositions that are bad relative to a range of candidate epistemic successes such as true belief and knowledge. In particular, giving up belief in response to higher-order evidence only when that evidence is not misleading would require subjects to have dispositions that discriminate between cases in which their original cognitive processes is fine, and cases in which they merely seemed to be fine. But, I argue, such dispositions are not normally humanly feasible. I show that retaining belief in putative cases of defeat by higher-order evidence is problematic irrespective of whether veritism or some form of gnosticism is true. In the end I contrast my account of dispositional evaluations with similar-sounding ideas that have been put forth in the literature, such as consequentialist views that focus on instrumental means to success. (shrink)

In this paper, we propose a new theory of rationality defeat. We propose that defeaters are "indicators of ignorance", evidence that we’re not in a position to know some target proposition. When the evidence that we’re not in a position to know is sufficiently strong and the probability that we can know is too low, it is not rational to believe. We think that this account retains all the virtues of the more familiar approaches that characterise defeat in terms of (...) its connection to reasons to believe or to confirmation but provides a better approach to higher-order defeat. We also think that a strength of this proposal is that it can be embedded into a larger normative framework. On our account the no-defeater condition is redundant. We can extract our theory of defeat from our theory of what makes it rational to believe—it is rational to believe when it is sufficiently probable that our belief would be knowledge. Thus, our view can provide a monistic account of defeat, one that gives a unifying explanation of the toxicity of different defeaters that is grounded in a framework that either recognises knowledge as the norm of belief or identifies knowledge as the fundamental epistemic good that full belief can realise. (shrink)

This paper is about the epistemology of perceptual experiences that have enriched high-level content. Enriched high-level content is content about features other than shape, color, and spatial relations that has a particular etiology. Its etiology runs through states of the agent that process other perceptual content and output sensory content about high-level features. My main contention is that the justification provided by such experiences is not foundational justification. This is because the justification provided by such experiences is epistemically dependent on (...) having justification to believe certain claims about the content relevant for enrichment—claims about what I call the corresponding features. (shrink)

Phenomenal Conservatism (the view that an appearance that p gives one prima facie justification for believing that p) is a promising, and popular, internalist theory of epistemic justification. Despite its popularity, it faces numerous objections and challenges. For instance, epistemologists have argued that Phenomenal Conservatism is incompatible with Bayesianism, is afflicted by bootstrapping and cognitive penetration problems, does not guarantee that epistemic justification is a stable property, does not provide an account of defeat, and is not a complete theory of (...) epistemic justification. This book shows that Phenomenal Conservatism is actually immune to some of these problems, though not all of them. Accordingly, it explores the prospects of integrating Phenomenal Conservatism with Explanationism (the view that epistemic justification is a matter of explanatory relations between one’s evidence and propositions supported by that evidence). The resulting theory, Phenomenal Explanationism, has advantages over Phenomenal Conservatism and Explanationism taken on their own. Phenomenal Explanationism is a highly unified, comprehensive internalist theory of epistemic justification that delivers on the promises of Phenomenal Conservatism while avoiding its pitfalls. (shrink)