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Fallibilism: Evidence and Knowledge

Fallibilism: Evidence and Knowledge Jessica Brown

1

3

Great Clarendon Street, Oxford, OX2 6DP, United Kingdom Oxford University Press is a department of the University of Oxford.

It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries © Jessica Brown 2018 The moral rights of the author have been asserted First Edition published in 2018 Impression: 1 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by licence or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this work in any other form and you must impose this same condition on any acquirer Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America British Library Cataloguing in Publication Data Data available Library of Congress Control Number: 2017955562 ISBN 978–0–19–880177–1 Printed and bound by CPI Group (UK) Ltd, Croydon, CR0 4YY

For my mother

Contents Preface

ix

1. Human Fallibility and Fallibilism about Knowledge

1

2. The Evidential Commitments of Infallibilism

26

3. Infallibilism and Evidential Support

45

4. The Knowledge View of Justification and Excuse

67

5. Closure and Defeat

100

6. Undermining Defeat

126

7. Knowledge, Chance, and Practical Reasoning

153

8. Conclusion

184

References Index

187 195

Preface For much of the twentieth century, most non-sceptical epistemologists embraced a fallibilist view on which one can know a proposition on the basis of evidence which doesn’t guarantee the truth of the proposition known. However, more recently, infallibilist ways of thinking have become increasingly popular. Moreover, many contemporary infallibilists insist that they can avoid scepticism. This book examines the prospects for non-sceptical infallibilism. In particular, it focuses on the possibility of a non-sceptical infallibilism which rejects any kind of shifty view of knowledge, whether contextualist, relativist, or subject-sensitive invariantist.

The availability of a non-shifty non-sceptical infallibilism seems to depend on whether such a view can defend a generous enough conception of evidence to allow us to have the knowledge we ordinarily take ourselves to have. In particular, such an infallibilist needs to allow that our evidence extends well beyond how things seem to us in our experience and includes claims about the external world. Thus, the infallibilism which is the focus of this book is committed to a generous conception of evidence. More precisely, I argue that it is committed to the following claims about evidence and evidential support: if one knows that p, then p is part of one’s evidence, and p is evidence for p. However, I argue that these claims about evidence and evidential support are problematic. Furthermore, I argue that fallibilism can overcome the most serious objections levelled at it. So, I conclude that epistemologists who aim to avoid both scepticism and a shifty view of knowledge should be fallibilists.

As some readers may be interested in different parts of the book, in what follows I give a brief sketch of its contents. (A more detailed description of each of the chapters can be found at the end of chapter 1.)

Chapter 1 sets the stage for the subsequent discussion. I distinguish between fallibilism and infallibilism, and outline some of the recent motivations for infallibilism. I explain the book’s focus on non-shifty versions of infallibilism and defend the entailment definition of infallibilism used throughout the book.

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PREFACE

In chapter 2, I consider the conception of evidence and evidential support to which a non-shifty infallibilist is committed if she is to avoid scepticism. I argue that she is committed to a factive conception of evidence on which knowledge is sufficient for evidence. Further, I argue that she is committed to the following claim about evidential support: if one knows that p, then p is part of one’s evidence for p. Those already convinced that a non-shifty infallibilist has these commitments may want to omit chapter 2, and move directly to chapters 3 and 4 in which I argue that these claims about evidence and evidential support are problematic.

Chapter 3 criticizes the view that if one knows that p, then p is part of one’s evidence for p. I argue that this view cannot explain why it is typically infelicitous to cite a proposition which is evidence as evidence for itself, whether by appeal to pragmatics or an error theory.

Chapter 4 criticizes a factive view of evidence on which knowledge is sufficient for evidence. As is well-known, this view has the counterintuitive result that certain pairs of subjects who are intuitively equally justified, e.g. a person and a BIV, are not equally justified. However, defenders of this view of evidence have attempted to reply to this objection by distinguishing whether a belief is justified from whether it is blameless. They endorse the knowledge view of justification according to which a belief is justified if and only if known. I argue against the knowledge view of justification that it has difficulty explaining the propositional and graded senses of justification. In addition, I argue that it fails to provide an adequate account of blameless belief.

After arguing that infallibilism faces serious problems, I turn to consider objections levelled at fallibilism. In chapters 5 and 6, I consider the objection that fallibilism undermines closure for knowledge. In reply, it’s been argued that closure fails for reasons quite independently of the fallibilism–infallibilism debate, specifically because of defeat. If that’s right, then closure provides no reason to prefer infallibilism over fallibilism. However, the very idea of defeat has come under recent attack. Thus, the most substantial contribution of chapters 5 and 6 is to provide an extended defence of a variety of kinds of defeat including rebutting, undermining, and higher-order. Thus, I conclude that closure provides no reason to favour infallibilism over fallibilism.

In chapter 7, I argue that while, at first sight, fallibilism might seem to have particular difficulties with practical reasoning and concessive knowledge attributions, in fact fallibilism and infallibilism face similar

PREFACE

xi

puzzles and have the same broad options of response. As a result, practical reasoning and concessive knowledge attributions don’t provide reason to reject fallibilism.

I conclude that those of us who want to reject scepticism within a traditional non-shifty view of knowledge should embrace fallibilism. To avoid scepticism, a non-shifty infallibilist is committed to problematic claims about evidence and evidential support. By contrast, objections to fallibilism often thought devastating can be answered. Given the pre-theoretical attractiveness of fallibilism, we should be fallibilists.

I have been thinking about the issues discussed in this book for many years. A Fellowship at the Institute of Advanced Study at Durham in 2016 enabled me to bring the material together into the form of a book.

Thank you to the Institute and its Director, Professor Veronica Strang, for this wonderful opportunity.

I have presented material from the book in a large number of different venues, including talks at the 2016 Episteme conference, South Africa; the 2016 APA Central Division meeting in Chicago; the 2015 Epistemic Norms conference at Leuven University; the 2015 Templeton Science of Intellectual Humility summer seminar at Pasadena, and Capstone conference at Catalina Island; the workshops Evidence and Reasons, and Rationality and Knowledge at Geneva (2014, 2015); the Evidence workshop at Kent (2014); the Aims and Norms workshop in Oslo (2013); together with seminars at Durham, Edinburgh, Oxford, Princeton, Rutgers, St Andrews, and Sheffield. I would like to thank all the philosophers who have provided useful feedback on these talks as well as draft chapters. There are too many to list, but I would like to particularly mention my colleagues at St Andrews, as well as Cohen, Comesana, Douven, Dutant, Engel, Gerken, Goldberg, Goldman, Graham, Dan Greco, Hawthorne, Kelp, Lackey, Lasonen-Aarnio, Littlejohn, McGrath, McGlynn, Nagel, Pryor, Rysiew, Schaffer, Schechter, Schellenberg, Schnurr, Schoenfield, Sillins, Simeon, Martin Smith, Sosa, Vogel, Weatherson, Weisberg, and Williamson. Further, I want to thank Ram Neta and Baron Reed who provided detailed comments on the draft of the whole book.

Several chapters of the book draw on previously published work. In particular, the third chapter draws substantially on two of my previously published articles (Brown, “Infallibilism, evidence and pragmatics”, Analysis 2013; and Brown, “Evidence and epistemic evaluation”, Oxford

xii

PREFACE

Studies in Epistemology volume 5, 2015). The fourth chapter employs some material from my 2017 article in Episteme, “Blame and wrongdoing”. The first half of chapter 6 draws heavily on my 2008, Noûs article, “Subject-Sensitive Invariantism and the Knowledge Norm for Practical Reasoning”. I want to thank the editors of these journals for permission to reuse material from these articles in this book.

Finally, thanks to Peter Momtchiloff at Oxford University Press for all his efficiency, good advice, and support.

1 Human Fallibility and Fallibilism about Knowledge 1.1 Introduction This chapter sets the scene for the rest of the book. I distinguish fallibilism and infallibilism, and outline the main motivations for each position (sections 1.2 and 1.3). I explain how contemporary infallibilists argue that they can avoid scepticism, either by appeal to a shifty view of knowledge such as contextualism, and/or by appeal to a generous conception of evidence. I explain why the book focuses on the second option—the availability of a non-sceptical infallibilism which rejects a shifty view of knowledge and accepts a generous conception of evidence (section 1.4).

I also defend the entailment definition of infallibilism used in the book from alternative accounts (section 1.5). At the end, I sketch the contents of the remaining chapters.

1.2 Fallibilism and Infallibilism We claim to know much about the world, including claims about material objects around us, the existence of other people with various mental states, claims about the future, and claims about the past. But there often seems to be a gap between our evidence and what’s known in the sense that our evidence doesn’t guarantee the truth of what is known.

For example, even if I can know from the weather forecast that tomorrow will be sunny, that the forecast says it will be sunny does not guarantee that it will be sunny tomorrow.

Sceptics attempt to exploit the apparent gap between our evidence and what we claim to know to undermine key types of knowledge, whether about the external world, other minds, the past, or the future. For



HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE

example, they argue that a recently envatted1 brain (or BIV) could have just the same experiences as a person even though the BIV’s experiences radically misrepresent its environment. So, that I’m now having an experience as of typing on a computer does not guarantee that I am typing on a computer. Instead, I might be a handless BIV merely being stimulated to have such experiences. Thus, if one’s perceptual evidence just consists in claims about how things seem to one in experience, then how does one know that one’s a person rather than a BIV? While sceptics hope to use the apparent gap between evidence and what we claim to know for sceptical ends, most contemporary epistemologists draw a different conclusion. They claim that one can know even if one lacks evidence which guarantees the truth of what’s known. They embrace ‘fallibilism’: one can know that p even though one’s evidence does not guarantee the truth of p. By contrast, ‘infallibilism’ is the view that one can know that p only if one’s evidence guarantees the truth of p. Fallibilism was the default view in epistemology for much of the twentieth century. For, many thought that endorsing fallibilism was the only way to avoid scepticism about knowledge. Further, fallibilism seems initially plausible. For many important kinds of knowledge, what’s intuitively one’s evidence does not guarantee the truth of what one knows.

Despite the historic popularity of fallibilism, infallibilism is undergoing a contemporary renaissance, with characteristically infallibilist ideas being defended by a range of philosophers. There are several major sources of this current interest in infallibilism. One source is contextualism about knowledge-ascriptions, especially that inspired by the work of David Lewis. Lewis (1996) starts his explication of his contextualist view by saying, ‘I propose to take the infallibility of knowledge as my starting point.’ He explicitly motivates his version of contextualism as a way to avoid what he sees as the twin perils of fallibilism and scepticism, saying: Better fallibilism than scepticism; but it would be better still to dodge the choice.

I think we can. We will be alarmingly close to the rock [of fallibilism], and also alarmingly close to the whirlpool [of skepticism], but if we steer with care, we can—just barely—escape both. (550)2 1 Throughout the book, I assume that the brain has been recently envatted as this lets us set aside the worry that, due to content externalism, a person and an always envatted brain would have different mental states in virtue of their relations to different environments.

I leave this assumption implicit in the rest of the book.

2 Lewis-style contextualism is defended in, inter alia, Neta (2011), Schaffer (2005), and Blome-Tillmann (2009). Neta (2011) endorses a form of infallibilism on which ‘for S to

HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE



A second major source of contemporary infallibilist claims is the increasing popularity of generous conceptions of evidence on which one’s evidence doesn’t only include claims about one’s experiences, but also claims about the external world. Such a generous conception of evidence makes it easier to be an infallibilist and yet avoid scepticism. Such generous conceptions of evidence have been defended by a range of philosophers including epistemological disjunctivists, as well as those who endorse Williamson’s identification of one’s evidence and one’s knowledge.

Disjunctivists about experience hold that the state of its looking to one as if p may be constituted either by one’s seeing that p or it’s merely appearing to one as if p (e.g. Snowden 1980 and McDowell 1982).3 McDowell argues that such a disjunctivist approach can allow for a characteristically infallibilist approach to knowledge. He criticizes what he calls a ‘criterial view’ which ‘envisage[s] ascribing knowledge on the strength of something compatible with the falsity of what is supposedly known’. He comments, ‘it is a serious question whether we can understand how it can be knowledge that is properly so ascribed’ (1982: 372).

After criticizing the ways of thinking which he suggests lead to the criterial view, he suggests an alternative conception of experience on which, when things are going well, ‘the appearance that is presented to one . . . is a matter of the fact itself being disclosed to the experiencer’. So understood, when things are going well, there is no gap between the sensory appearance and the fact known for the appearance consists in the relevant fact being made perceptually manifest to one (386–7). Thus, McDowell motivates his disjunctivism about appearances by appeal to a recognizably infallibilist way of thinking of knowledge.

know that p, S must have reasons for believing that p which are such that S can know, by reflection alone, that she has those reasons, and that she could not possibly have those reasons if p is not true’ (658). Schaffer (2005) describes his contrastivist form of a relevant alternatives style of contextualism as ‘restricted infallibilism’. On his contrastive approach, the apparently binary ‘S knows that p’ is implicitly of the contrastive form: S knows that p rather than q. He says ‘S knows that p rather than q if and only if 1) p, 2) S has proof that p rather than q, and 3) S is certain that p rather than q, on the basis of 2)’. This is ‘infallibilist in so far as it requires proof, which is conclusive evidence, evidence that could not possibly obtain without p being true. But it is restricted insofar as the space of possibilities open to disproof is restricted to:{p}U{q}’ (255).

3 While Snowden (1980) also defends a disjunctive conception of experience, his main concern seems to be with the nature of perception, rather than with epistemological concerns. See the useful distinction between experiential and epistemological disjunctivism in Haddock and MacPherson 2008.

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HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE

Williamson (2000) provides a different way of defending a generous conception of evidence, namely by his equation of evidence and knowledge. While Williamson does not motivate his view of evidence by appeal to infallibilism, an infallibilist approach to knowledge seems to be made available by his equation of evidence and knowledge. If one’s evidence just is one’s knowledge, then whenever one knows that p, p is part of one’s evidence. So, if one knows that p, one’s evidence entails that p and gives it probability 1.

Before examining some of the motivations for this infallibilist renaissance, it’s useful to say a little more about how to define fallibilism and infallibilism. So far, I’ve roughly described these positions in terms of whether they hold that knowledge requires evidence which guarantees the truth of what’s known. However, if we want to tighten up this informal notion of a ‘guarantee’ of truth, we need to take a stand on the ontology of evidence. If one accepts the widespread view that evidence is propositional, then one can understand the notion of a guarantee in terms of entailment.

Thus, we can understand the infallibilist as holding that one knows that p only if one’s evidence entails that p. By contrast, if evidence need not be propositional, we cannot understand infallibilism in terms of a relation, such as entailment, that obtains only between propositions. Thus, to get beyond the rough intuitive statement of the debate, we need to take a stand on the ontology of evidence. I will be assuming throughout the book that evidence is propositional, and I will formulate the debate by appeal to the notion of entailment.4 Thus, I will take it that the infallibilist holds, and the fallibilist denies, that knowing that p requires evidence which entails that p. While I formulate infallibilism as an entailment claim for most of the book, in this introductory chapter I sometimes talk of whether knowledge that p requires evidence that rules out every not-p possibility to describe the views of some infallibilists who deny that evidence is propositional, such as Lewis. In addition, in section 1.5, I explain why I prefer the entailment formulation of the debate to some other rival formulations.

4 For some influential arguments that evidence is propositional, see Williamson 2000.

Examples of the entailment definition of infallibilism can be found in Feldman 1981: 266–7, Cohen 1988: 91, Pryor 2000: 520, Reed 2002: 144, Conee and Feldman 2004: chapter 12, Stanley 2005a: 127, Dougherty and Rysiew 2009, and Littlejohn 2011: 603. Others mention the entailment view before going on to suggest alternative definitions of infallibilism including Hetherington 1999, Reed 2002, and Fantl and McGrath 2009.

HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE



In the next section (1.3), I sketch some of the reasons recently given for infallibilism, before examining how contemporary versions of infallibilism claim to avoid scepticism. My choice of motivations for infallibilism is selective and designed to focus on those motives which are available within the dominant externalist approach to epistemology which holds that the epistemic status of a belief can depend on factors of which one is ignorant, such as the reliability of the process by which the belief was formed, or the absence of Gettier factors.5

1.3 Motivations for Infallibilism Infallibilism is often motivated by the thought that there seems something contradictory or problematic in a fallibilist conception of knowledge. It seems problematic to simultaneously claim knowledge and admit the possibility of error. For instance, consider the infelicity of the following statements: ‘I know that I have hands but I might be a handless brain in a vat’, or ‘Anne knows that Beatrice stole the cookies, but it might instead have been Christina’. The infelicity of such so-called concessive knowledge attributions6 seems to pose problems for the fallibilist. For it might be thought that if fallibilism is true, then concessive knowledge attributions would be literally true. After all, if it is possible to know that p even though one’s evidence is compatible with various not-p possibilities then surely it should be true to claim knowledge and simultaneously admit the possibility of error? For instance, Lewis (1996) says, ‘If you are a contented fallibilist, I implore you to be honest, be naive, hear it afresh.

“He knows, but has not eliminated all possibilities of error.” Even if you’ve 5 Thus, I’m setting aside motivations for infallibilism which arise within an internalist approach, including certain motivations given by McDowell and Neta. In rejecting the fallibilist idea that one might truly ascribe knowledge on the strength of something compatible with the falsity of what is known, McDowell says, ‘one’s epistemic standing on some question cannot be intelligibly constituted, even in part, by matters blankly external to how it is with one subjectively. For how could such matters be other than beyond one’s ken? And how could matters beyond one’s ken make any difference to one’s epistemic standing?’ (1982: 390). However, such expressions of internalism will have little purchase on those already persuaded of an externalist approach. Neta (2011) argues for a form of infallibilism from what he describes as the ‘Cartesian’ claim that S knows that p only if S has an epistemic reason r for believing that p such that S can know by reflection alone that she has r and that r is a reason for believing that p (658). Most externalists would reject the Cartesian premise of this argument.

6 This term is from Rysiew 2001.

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HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE

numbed your ears, doesn’t this overt, explicit fallibilism still sound wrong?’

(550).7 So the infelicity of concessive knowledge attributions has been taken to be evidence for infallibilism.

In addition to the concern about concessive knowledge attributions, fallibilism faces the so-called threshold problem. According to infallibilism, one can know that p only if one’s evidence entails that p. If one’s evidence entails that p, then the conditional probability of p on one’s evidence is 1. Thus, the infallibilist holds that one can know that p only if the probability of p on one’s evidence is 1. By contrast, the fallibilist holds that one can know that p even if one’s evidence does not entail that p and even if the probability of p on one’s evidence is less than 1. However, the fallibilist would hold that one cannot know that p unless p is highly likely on one’s evidence. So, the fallibilist presumably holds a threshold view according to which one can know that p only if its probability on one’s evidence exceeds some threshold, t, where that threshold is high but less than 1. But this raises the question of where the threshold is set.

For instance, suppose that the fallibilist suggests that the threshold is 0.92. Any such choice seems arbitrary: why not 0.93 or 0.91 rather than 0.92? Bonjour (2002) comments, ‘it is simply unclear what sort of basis or rationale there might be for fixing this level of justification in a nonarbitrary way’ (43).8 A further worry is that wherever the threshold is set, if it is less than 1, then certain non-knowledge beliefs can meet the threshold. For instance, many hold that one cannot know that one’s lottery ticket is a loser before the draw is announced merely on the basis of the probabilities. But by increasing the size of the lottery one can make the probability that one’s ticket is a loser as high as possible, short of 1. So, the belief that one’s ticket is a loser would meet any plausible threshold short of 1.

By contrast with the fallibilist, the infallibilist might seem to have an advantage. The infallibilist’s view that knowledge requires probability

7 Some fallibilists agree that fallibilism has the upshot that concessive knowledge attributions are literally true but attempt to offer an explanation of why they are nonetheless infelicitous (e.g. Dougherty and Rysiew 2009, and Fantl and McGrath 2009). Others argue that fallibilism does not have this upshot (see Stanley 2005a). See chapter 7 for further discussion.

8 Some fallibilists appeal to pragmatic encroachment to provide a non-arbitrary account of the threshold (e.g. Fantl and McGrath 2009). However, I set aside shifty views including pragmatic encroachment in section 1.4 below.

HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE

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1 might seem less open to the charge of being arbitrary. 1 seems to be a natural rather than an arbitrary threshold. Furthermore, appeal to probability 1 can be used to explain why one lacks knowledge that one’s lottery ticket is a loser before the draw has been announced. In addition, if knowledge requires probability 1 then this may help to explain the value of knowledge. If p has probability 1 on one’s evidence, then not-p has probability 0. Thus, the infallibilist can explain the value of knowing that p as consisting in the fact that it requires evidence which rules out the possibility that not-p. As we will see, the infallibilist might appeal to the fact that knowledge has probability 1 to explain what she takes to be a further important property of knowledge, namely that it is closed across known implication.

The idea that knowledge is closed across known implication can be initially formulated as the idea that if one knows each of p1-n, and comes to believe that q by competently deducing q from p1-n, then one knows that q. Closure for knowledge has seemed very attractive to many.9 For, it might simply seem to be a formalization of the idea that we can gain knowledge by deductive inference. But fallibilism seems to threaten the closure of knowledge across deductive inference. Imagine that, as we’ve supposed, the fallibilist endorses the threshold conception on which knowledge that p requires that the probability of p on one’s evidence exceeds a threshold, t, where t is less than 1. As is well known, this threshold conception may give rise to the failure of closure for knowledge.

For one could meet the threshold condition for knowing the premises of some valid inference, come to believe the conclusion by competent deduction from the premises, and yet not meet the threshold condition for knowing the conclusion. Although for each premise individually considered, the chance of error is compatible with one’s knowing it, the chance of risk accumulates across the inference so that the chance is too great for one to know the conclusion. As a result, one might know the premises of the deduction, come to believe the conclusion by competent deduction from the premises, and yet not know the conclusion.

9

Recent defenders include, inter alia, Cohen 1988, DeRose 1995, Kaplan 1998, Williamson 2000, Hawthorne 2004 and 2005, and Schaffer 2004. Well-known opponents include sensitivity theorists (e.g. Nozick 1981), some relevant alternatives theorists (e.g.

Dretske 1970), and those defending a threshold condition on the relevant epistemic status (e.g. Christensen 2004).

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HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE

The point can be vividly illustrated with the preface paradox.10 Suppose that each premise of an argument corresponds to a claim made in a very large book of history and the conclusion deduced is the conjunction of all these individual claims. Most actual books of history contain a few errors. However, let’s suppose that the author of this particular book does know each of the claims contained within it. So, she meets the fallibilist’s threshold condition for knowing each premise. Nonetheless, even if she deduces from these claims the conclusion which is their conjunction, she does not meet the fallibilist’s threshold condition for knowing the conclusion for, intuitively, the risk of error is too great.

After all, she is well acquainted with the fact that most history books contain a few errors. Indeed, every other book she has ever read has contained a few errors, and she has no reason to think that she’s an exception to this general rule. So, she should think that it’s very likely that there is some error in her book. Thus, even if she does in fact know each of the claims in the book, she doesn’t know the conjunction of these claims.

Since the problem fallibilism faces in accommodating closure for knowledge arises from allowing that the threshold of probability required for knowledge may be less than 1, infallibilism seems to avoid the problem. Suppose that one knows the premises of a valid argument and comes to believe the conclusion by competent deduction from these premises. Assuming infallibilism, if one knows the premises of the argument, each of these premises has probability 1 on one’s evidence.

Given this, and the further fact that the premises taken together entail the conclusion, it follows that the conclusion has probability 1 on one’s evidence. Thus, on the infallibilist view, there cannot be a case in which one knows the premises of a valid inference and yet the conclusion of that inference fails to have probability 1 on one’s evidence. Thus,

10 An alternative illustration is provided by the lottery paradox. Suppose there is a large lottery such that for each ticket individually considered, the probability on the evidence that it will lose exceeds the threshold, t. Nonetheless, the probability on the evidence that every ticket will lose is less than the required threshold. If the fallibilist supposes that any true belief meeting the threshold condition is knowledge, then this provides a counterexample to closure for knowledge. However, the preface is a more useful example of closure failure since it is arguable that one does not know the premises of the lottery paradox. Indeed, a fallibilist can accept this if she denies that it is sufficient for a true belief to be knowledge that it meets the threshold condition.

HUMAN FALLIBILITY AND FALLIBILISM ABOUT KNOWLEDGE



unlike fallibilism, the probabilistic condition imposed by infallibilism about knowledge is closed across known implication.11 The fact that fallibilism allows one to know without having evidence which entails what is known is also relevant to debates about practical reasoning. It’s become recently popular to argue that knowledge is the norm of practical reasoning in the sense that one is in a good enough epistemic position to rely on p in one’s practical reasoning if and only if one knows that p (e.g. Hawthorne and Stanley 2008). But, according to fallibilism, knowing that p is compatible with p’s having a probability on one’s evidence of less than 1. But, as the stakes involved in acting on p rise, the possibility that not-p is of increasing importance. At some level of risk, one should no longer act on p even if one still knows that p. So, it can seem that fallibilism conflicts with the knowledge norm for practical reasoning.

In later chapters, I discuss in detail how the fallibilist should respond to these challenges concerning concessive knowledge attributions, closure, practical reasoning, and the threshold problem. But, for now, what’s important to note is that these issues may be thought to motivate an infallibilist conception of knowledge. Further, recent developments in epistemology seem to offer the infallibilist a way to avoid scepticism.

Taken together with the motivations for infallibilism, this might seem to constitute a strong case for infallibilism. So, let us now examine the main infallibilist strategies for avoiding scepticism.

1.4 Infallibilist Strategies for Avoiding Scepticism An initial intuitive worry that the infallibilist may have difficulties avoiding scepticism might arise from the thought that humans are obviously fallible creatures. There is much we are ignorant of, and perhaps cannot possibly understand given our limited cognitive and conceptual capacities.

We often make mistakes and have false beliefs. That we have false beliefs is unsurprising when we reflect on the fallibility of such processes of beliefformation as forming beliefs about the world via perceptual experience, 11 That the probabilistic condition infallibilists place on knowledge does not generate closure failure does not show that nothing else generates closure failure on the infallibilist view. I discuss this issue in chapter 5, and argue that closure fails due to defeat.

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testimony, or apparent memory. For, that one has a perceptual experience as of p does not entail that p, that one apparently remembers that p does not entail that p, and that someone testifies that p does not entail that p.

However infallibilism is compatible with our obvious fallibility. The infallibilist has no need to deny that there is much we are ignorant of, or that we often have false beliefs. Her claim concerns the position of someone who knows, not someone who lacks knowledge either through lacking belief, or failing to believe the truth. Furthermore, she needn’t deny that, on certain ways of typing belief-forming processes, they are fallible. For example, she should accept that beliefs formed via apparent memory, apparent perception, or testimony can lead to false belief.

Whether she can argue that there are other ways of typing belief-forming processes on which they are not fallible is a further question that we will examine later in chapter 2. But, for now, the main point to note is simply that there is no obvious contradiction between the infallibilist claim about the strength of the relation between evidence and knowledge when one has knowledge, and the fact that humans often fail to know the truth, and that on some ways of typing human belief-forming processes, they can lead to falsehood.

While infallibilism is not inconsistent with the obvious facts of human fallibility, a more serious worry is whether the infallibilist can close the apparent gap between our evidence and what we know. For instance, that one has an experience as of hands does not entail that one has hands; that one apparently remembers that p does not entail that p; and that someone testifies that p does not entail that p. So the challenge for the infallibilist is to show how we can have the kind of knowledge we ordinarily take ourselves to have even on the infallibilist conception on which knowing that p requires having evidence that entails that p.

Contemporary epistemology offers infallibilists two main strategies to try to avoid scepticism about knowledge even while holding that knowledge that p requires evidence ruling out every not-p possibility.

They could employ either a shifty view about what it is to have evidence which rules out all not-p possibilities or a more generous view about what one’s evidence is. To the extent that ruling out all not-p possibilities is a shifty matter, or one’s evidence is richer, the easier it is to show that infallibilists need not be sceptics. I now consider each of these two strategies in turn, arguing that the infallibilist is best advised to set aside the first shifty strategy, to focus on the second strategy of being

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generous about the evidence. Of course, not all of those defending either a shifty account of knowledge or a generous conception of evidence would regard themselves as infallibilists, or want to use these views to defend infallibilism. Nevertheless, both shifty accounts of knowledge and generous accounts of evidence offer a potential way to defend non-sceptical infallibilism.

According to certain shifty views of knowledge, it is true for a subject to claim knowledge only if she has evidence which eliminates or rules out every not-p possibility. Given the requirement that a knower can eliminate every not-p possibility, the view could be considered to be broadly infallibilist.12 Yet, defenders of these shifty views allow that one can truly claim to know that p even if one’s evidence doesn’t rule out every logically possible alternative. Instead, the requirement is merely that one rules out every not-p possibility that is relevant, where these are a subset of the logically possible alternatives.13 While in principle such a shifty infallibilist view could take the form of any of contextualism, relativism, or pragmatic encroachment, it’s been developed in most detail for contextualism.14 So, I’ll focus on how contextualism offers the infallibilist a way to avoid scepticism.

Lewis (1996) argues that a knowledge ascription of the form ‘S knows that p’ is true if and only if S’s evidence eliminates every possibility in which not-p. However, it turns out that what counts as a possibility depends on the context. As a result, even though Lewis identifies one’s evidence with one’s experiences, his contextualism allows him to claim 12 Here I’m taking a more informal notion of infallibilism than the entailment view which will be the book’s focus. For, defenders of shifty views don’t require evidence to eliminate every logically possible alternative, and some reject propositional views of evidence.

13 By contrast, invariantist versions of relevant alternatives theories do not seem properly termed infallibilist for they allow that in a single context it may be true to say ‘I know that I have hands although I cannot rule out the possibility that I’m a BIV’. On Lewis’s contextualism, such statements cannot be true since once a possibility is mentioned, it is relevant and so undermines the truth of the relevant knowledge ascription.

14 These views differ both over whether ‘knows’ always expresses the same property in different contexts and over what determines which possibilities are relevant. Contextualists claim that ‘knows’ expresses different properties in different conversational contexts; on relativism and pragmatic encroachment, ‘knows’ expresses the same property in different conversational contexts. For the contextualist, it’s the conversational context of those attributing knowledge that determines which possibilities are relevant; for the relativist, it is the standards of those assessing knowledge attributions; and on pragmatic encroachment views, it is the stakes for the subject of the knowledge attribution.

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that, ordinarily, one can truly claim to know, e.g. that one is typing on a computer. For, one’s experience as of typing on a computer eliminates the alternatives ordinarily relevant, such as that one has lost one’s hands in an accident and only has stumps. In the situation in which one has lost one’s hands one wouldn’t be having the experience as of typing on a computer.15 Of course, having that experience does not rule out some logical possibilities, such as the BIV possibility, but the BIV possibility is not ordinarily relevant.

Thus, shifty views, such as contextualism, offer one potential way to defend non-sceptical infallibilism. However, contextualism and other shifty views are highly controversial. In particular, it’s not clear that the kind of data about the shiftiness of knowledge ascriptions standardly used to motivate shifty views do in fact motivate them, as opposed to more traditional non-shifty views of knowledge. First, there is now a lively debate in experimental philosophy about precisely what are the data that need to be explained (e.g. see Buckwalter 2010, Feltz and Zarpentine 2010, Knobe and Schaffer 2012, Pinillos 2011, Buckwalter 2012, and May et al. 2016). Second, there is a range of non-shifty explanations of the data including explanations that appeal to traditional requirements for knowledge such as the belief condition (e.g. Bach 2005, Nagel 2010); explanations that appeal to the semantics-pragmatics distinction (e.g. Rysiew 2001 and 2007, Brown 2006), and explanations that appeal to a variety of error theories (e.g. Williamson 2005, Nagel 2008, Gerken 2013 and forthcoming). Indeed, there is an internecine debate between different shifty views about which is best able to explain the shiftiness in knowledge ascriptions (see, inter alia, Hawthorne 2004, MacFarlane 2005a, Stanley 2005b, Fantl and McGrath 2009, and DeRose 2009). Third, particular shifty views face specific objections.

For instance, contextualism faces the problem of finding a suitable semantic model for the shiftiness of ‘knows’ (e.g. Schiffer 1996, Stanley 2005b). On pragmatic encroachment, whether one knows depends on the stakes for the subject in a way many find problematic. Pragmatic encroachment views also face difficulties with various embedded and modal claims (Hawthorne 2004: 166–7, Stanley 2005b: 113–14, Fantl and McGrath 2009: 208–10, and DeRose 2009 chapter 6). Questions 15

On Lewis’s view, an experience eliminates a certain possibility when one doesn’t have that experience in that possibility.

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have also been raised about how a variety of shifty views can deal with the interpersonal role of knowledge in testimony and memory (Hawthorne 2004, MacFarlane 2005b, Williamson 2005, Schaffer 2006, and Blaauw 2008).

Even setting aside these objections to shifty views per se, one might question the extent to which they truly offer a non-sceptical version of infallibilism. First, their very shiftiness means that they allow that it can be true to say that a subject knows that p even if her evidence does not rule out every logically possible alternative to p, but only those which are relevant (whether relevant in the conversational context, given the assessor’s standards, or given the subject’s stakes). So they might equally be seen as fallibilist, rather than infallibilist, views. Indeed, some have defended shifty views as the best way of defending fallibilism (e.g. Cohen 1988, Fantl and McGrath 2009). Second, it is debatable whether at least some shifty views, e.g. contextualism, offer a non-sceptical view rather than simply giving in to scepticism at least in certain conversational contexts.

Given these objections, a defence of infallibilism which employs a shifty view involves the large task of defending the relevant shifty view from objections. Rather than taking on this task, I would prefer to investigate the prospects for infallibilism within a non-shifty view of knowledge. So a non-shifty defence of infallibilism will be the focus of this book. While shifty views attempt to defend non-sceptical infallibilism by allowing that the range of alternatives one’s evidence needs to eliminate in order to truly claim knowledge shifts, non-shifty views deny this. Instead, they claim that one knows that p only if one has evidence which rules out every logically possible alternative to p. To do this, we will see that they need to appeal to a generous conception of evidence.

Although the book will focus on a non-shifty version of infallibilism which employs a generous conception of evidence, the discussion should nonetheless be of some interest to those who prefer a shifty defence of infallibilism. First, to the extent that a generous conception of evidence is independently plausible, the defender of a shifty view might wish to adopt such a conception herself. Thus, she may be interested in seeing how far a generous conception of evidence can help defend infallibilism.

Indeed, some have combined the two strategies of adopting a shifty view and a generous conception of evidence to defend infallibilism (e.g. Neta’s (2003) version of contextualism). Second, to the extent that it turns out