Contextualism, Externalism and Epistemic Standards

MICHAEL WILLIAMS

CONTEXTUALISM, EXTERNALISM ANDEPISTEMIC STANDARDS1

1. INTRODUCTION

I want to discuss an approach to knowledge that I shall call “simpleconversational contextualism” or SCC for short. Proponents of SCCthink that it offers an illuminating account of both why scepti-cism is wrong and why arguments for scepticism are so intuitivelyappealing. I have my doubts.

SCC was first developed in detail by Stewart Cohen, followinga suggestion of David Lewis. But whereas Cohen’s version of SCCinvolves linking knowledge with justification, Lewis himself thinksthat contextualist ideas are best worked out without supposing anyessential connection between the two, a view endorsed by KeithDeRose.2 Since I have discussed a justificationist version of SCCelsewhere, in connection with some of Robert Fogelin’s ideas,3 itis conversational contextualism in its non-justificational or “exter-nalist” version that I shall mostly be considering here. To keepthe discussion within bounds, I shall restrict most of my detailedcommentary to externalist SCC in Lewis’s version. But I hope itwill be clear that my objections are more thanad hominem. Notonly do the problems I find arising Lewis haunt other externalistcontextualists, such as De Rose, my deepest reservations, I believe,apply to SCC in all its forms.

2. SIMPLE CONVERSATIONAL CONTEXTUALISM

Consider: you ask me whether I know when the next train leavesfor the city and I tell you “Yes, two o’clock.” Imagine that I have I

This paper is accompanied by Timothy Williamson comments (seepp. 25–33).

Philosophical Studies103: 1–23, 2001.© 2001Kluwer Academic Publishers. Printed in the Netherlands.

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have derived my information from an impeccable source, such asthe latest timetable, so that it seems clear that I really do know.However, you explain that you have an appointment that youabsolutely cannot miss. Moreover, it does happen occasionally thatrepairs to the track require temporary timetable changes. Have Ilooked into whether any such changes have been announced fortoday? No. So do I really know that the next train leaves at two?Suddenly, things seen less clear.

Reflection on examples like this suggest the following ideas:

(i) Our practices of epistemic evaluation embody mechanismsthatraise and lowerthe standards for attributing knowledge.

(ii) this raising and lowering of standards consists in the expansionand contraction of the range of error-possibilities in play.

(iii) Standards are raised and lowered primarily by changes inthe conversationalcontext, in particular what claim has beenmade and/or by what error-possibilities (“defeaters”) havebeen brought up or are being attended to.

Epistemologies built around these ideas arecontextualistbecausethey admit that standards for attributing knowledge are subjectto contextual variability. They aresimplebecause they recogniseonly one principle dimension of epistemically relevant contextualvariation: the raising and lowering of standards. And they areconversationalbecause standards are raised and lowered by conver-sational developments: i.e. by what claims have been made or whaterror-possibilities have beenbrought up(explicitly or implicitly andeither in conversation with others or in some internal dialogue).I do not think that proponents of SCC are committed to holdingthat conversational developments are theonly factors capable ofeffecting changes in epistemic standards. However, it is essential toSCC that such developments besufficientto induce standard-shifts.

SCC links up with scepticism by way of an account of the specialcontext of epistemic evaluation created by philosophical reflection.In ordinary contexts, the error-possibilities we attend to are kept inbounds by various practical interests, such as my need to get to themeeting. But when reflecting philosophically, we step back from allsuch everyday concerns. Accordingly, to make a true knowledge-claim in the context of philosophical reflection, we need to be ableto rule out any and all possibilities of error, no matter how remote

CONTEXTUALISM, EXTERNALISM AND EPISTEMIC STANDARDS 3

or implausible. But we cannot do this: indeed, sceptical hypotheses– such as that I am the victim of an Evil Deceiver or a brain-in-a-vat– aredesignedto resist being ruled out.Thus SCC adopts

(iv) Philosophical reflection, or “doing epistemology,” createsa context where, because there is no limit on the error-possibilities that may brought into play, epistemic standardsrise to the maximal level, where they turn out to be unsatis-fiable.

At first, it seems that philosophical reflection shows that the scepticis right after all. When we set aside practical concerns and askwhether we ever really know anything about the external world, thevery way we ask the question seems to force us to answer “No.” But,given (i), (ii) and (ii) above, we can resist this conclusion. We needonly admit:

(v) Although doing epistemology raises standards so as to makesceptical conclusions true, this does not invalidate everydayknowledge-attributions, which are true at everyday standards.

Given that epistemic standards are subject to contextual variation,attributions of knowledge may indeed be false in the extraordinarycontext of philosophical reflection. But this does not mean that theyare false in more ordinary circumstances, when different standardsare in force. The aim of contextualism is thus to insulate everydayknowledge from sceptical undermining. Turning the point around,scepticism is not so much straightforwardly rejected as contained.

This way of dealing with scepticism is appealing for the fol-lowing reason: a good response to scepticism should be diagnosticand not merely dialectical. We do not want merely to be shownthatsceptical arguments go awry: we want an explanation of how theygo wrong that also accounts for why they can seem so compelling.This is just what contextualism offers. The sceptic is difficult todismiss because he is partly right: knowledge – or perhaps trulyclaiming or attributing knowledge – really is impossible in therarefied context of philosophical reflection. The sceptic’s (plausible)mistake is to think that this result licenses the conclusion that know-ledge is impossible generally. He takes himself to have discovered,while doing epistemology, that knowledge is impossible, when

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he has discovered only that knowledge is impossible while doingepistemology.

This conclusion can be taken two ways.4 One possibility is thatdoing epistemology temporarily destroys knowledge. Knowledge is“elusive – it comes and goes – because it can always be under-mined by unbridled reflection. Alternatively, we might say that wewhile we always know everyday things by everyday standards, wecannot defend that knowledge by explicit anti-sceptical pronounce-ments. So, although we ordinarily know that sceptical possibilitiesdo not obtain, we cannot express this knowledge in explicit claims.Knowledge-claims that bring sceptical possibilities into play createa context in which those claims are false. This position may haveaffinities with certain ideas of Wittgenstein, who stresses the impro-priety of claiming to know such things as that the Earth has existedfor many years past.

Still, however we interpret (v), the sceptic, while crucially wrong,is partially right. Either way, then, SCC explains why the intuitionsthat seem to lead to scepticism have such a grip on us. It is asatisfyingly diagnostic response to the sceptical problem.

3. VARIETIES OF SCEPTICISM

The question is not whether the kind of contextual variation high-lighted by SCC exists (it does) but whether a response to scepticismthat appeals only contextual sensitivity of this type isdiagnosticallyadequate. In approaching this question, I want begin with someremarks about why is scepticism a problem worth taking seriously.Then I want to discuss what sort of argumentative strategies mightlead to scepticism of a suitably problematic variety. These remarksare necessary, if we are to command a clear view of what SCC issupposed to accomplish.

Briefly, scepticism is a problem because the sceptic presents uswith apparently intuitive arguments for wholly unacceptable conclu-sions. In describing sceptical arguments as intuitive, I mean thatthey seem not to depend on elaborate or contentious theoreticalideas about knowledge or justification. If sceptical arguments wereobviously non-intuitive, we could dismiss them (as artifacts ofideas we are not compelled to accept). Equally, if they led only


to anodyne conclusions, we could accept them. But neither optionseems available, hence the problem.

There are two conditions that any type of scepticism must meetif it is to be properly unacceptable (hence worth taking seriously)today.

The first is that scepticism must make an unusually general claimabout our epistemic disabilities. The sceptic must do more thanremind us of our vast contingent ignorance, which none of us willdeny. While the exact nature of the generality of the sceptic’s claimsis a difficult matter, this much seems clear: the sceptic must issuea negative verdict on what seem pre-theoretically to be the clearestcases of knowledge, the cases such that, if we fail to have knowledgehere, it is hard to see where we could ever have it.

The second condition is that scepticism must be severe. Scepti-cism is often stated as the doctrine that knowledge is impossible.But whether this conclusion ought to bother us depends on howexacting we take the standards for knowledge to be. Scepticismthat results from setting extremely high standards for knowledgeis a problem only if we have some clear and compelling interestin living up to standards set that high. For example, philosophersof the early modern period restricted knowledge to truths that aredemonstratively certain: truths that are either themselves intuitivelyself-evident, or deducible by intuitively self-evident steps from self-evident premises. By this standard, we know very little, if anything.However, this is a conclusion that most of us are willing to live with,indeed eager to embrace. We are all fallibilists nowadays.

The general point is this: the more exacting the conditions forknowledge, the milder the scepticism that results from denying thatknowledge is possible. Or rather, this is true with respect to scep-ticism that isknowledge-specific. The need to distinguish betweenforms of scepticism that are knowledge-specific and forms that arenot is forced on us by Gettier’s argument to the effect that thestandard “justified-true-belief” analysis fails to state a sufficientcondition for knowledge. Many philosophers try to handle Gettier’sproblem by adding a “fourth clause,” restricting the type of justifica-tion capable of yielding knowledge. If we adopt this strategy, wemust recognise two ways of denying that knowledge is possible. Oneway concedes that lots of our beliefs have positive epistemic status

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– even high positive epistemic status – but denies that they havea high enough status to amount to knowledge properly so-called:that is, the sceptic allows that we can meet the first three condi-tions on knowledge, denying us only the ability to satisfy the fourth.This is what I mean by scepticism that is “knowledge-specific.”But another way is to reject our ability even to rise to the level tojustified belief, in effect to challenge our capacity for making well-founded distinctions with respect to epistemic status. This is radicalscepticism.

There are grades of knowledge-specific scepticism, depending onhow exacting the standards for knowledge are supposed to be. Mostfourth-clause theorists identify knowledge with true belief that isindefeasibly justified. Indefeasible justification is justification thatcannot be undermined by the acquisition of further true beliefs. Aneven more severe standard would be that knowledge requires abso-lute certainty: that it rest on evidence that excludes every logicallypossible “defeater” for the belief in question. This gives us a distinc-tion between indefeasibility-scepticism and certainty-scepticism,both of which are knowledge-specific.

By virtue of being knowledge-specific, both indefeasbility-and certainty-scepticism are forms of “high-standards” scepticism.Neither is much of a problem. To be sure, certainty-scepticism wascontroversial once upon a time (when the demonstrative ideal ofknowledge held sway), but it is not a very serious issue today. AndI am not sure that indefeasibility-scepticism is much more problem-atic. While it might be nice to have indefeasibly justified beliefs, wecan get along without them. And since we are not ever to be in aposition to know that our best available evidence is actually inde-feasible, the ideal of indefeasibility does not appear to be of muchmethodological significance. Indeed, it is not clear that knowledge-specific scepticism amounts to more than fallibilism, which is lessa problem than a rationally anti-dogmatic outlook. But there isno comparably benign way of viewing radical scepticism, whichthreatens to wipe out all distinctions of epistemic status. So I thinkthat scepticism is clearly a problem only if it is radical as well asgeneral.


4. EXTERNALISM AND RADICAL SCEPTICISM

Strategically, scepticism comes in two main varieties, Cartesian andAgrippan. In the broadest terms, Cartesian scepticism depends ongetting us to consider “sceptical hypotheses” – that I am the victimof Descartes’s Evil Deceiver or a brain in a vat – which seem difficultor impossible to rule out. To come to terms with Cartesian scepti-cism is to explain why such possibilities – or apparent possibilities– are not in fact the obstacles to everyday knowledge that they seemto be. Agrippan scepticism, which is centered on the problem of theregress of justification, has no particular connection with scepticalhypotheses.

SCC is concerned with Cartesian scepticism, offering an explan-ation of why the “remote” possibilities described by sceptical hypo-theses are not obstacles to everyday knowledge. SCC, in the formwe are considering, has nothing to say – or anyway nothing toadd – to discussion of Agrippan scepticism. Agrippan scepticismis essentially scepticism with respect to justification and concernsknowledge only to the extent that knowledge depends always andeverywhere on justification. But SCC, in the version under exam-ination, is developed in conjunction with radically externalist or“non-justificational” accounts of knowledge. For externalist advo-cates of SCC, Agrippan scepticism is handled by their externalism,before their contextualism comes on the scene.

Returning to Cartesian scepticism, how do sceptical hypotheseslead to sceptical conclusions? One suggestion is that sceptical hypo-theses poseunderdetermination problems. The crucial feature of thebrain-in-a-vat example is that the victim enjoys exactly the sameperceptual experience as he would in his normal state. But surely, thesceptic argues, when it comes to forming beliefs about the externalworld, perceptual experience is all that any of us has to go on.If this evidence fails to discriminate between our ordinary beliefsand bizarre counter-possibilities, how can those beliefs amount toknowledge?

For contextualists like Lewis and DeRose, this account ofCartesian scepticism links scepticism far too closely with “inter-nalist” or “evidentialist” ideas about knowledge. If Cartesian prob-lems depended essentially on such ideas, Cartesian scepticism, likeAgrippan scepticism, would be met by externalism alone, leaving

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no real work for contextualism to do. Accordingly, externalistproponents of SCC focus on an apparently simpler form of scepticalargument. Let ‘O’ be a proposition about the external world thatI would ordinarily take myself to know and ‘H’ a suitably chosensceptical hypothesis, such as that I am a brain in a vat. Then, inDeRose’s formulation, this “Argument from Ignorance” (AI) goesas follows:

1. I don’t know that not-H.2. If I don’t know that not-H, then I don’t know that O.3. So, I don’t know that O.

By itself, this reformulation gets us nowhere. Everything depends onthe sceptic’s reasons for affirming 1. If these turn out to involve theundetermination of worldly knowledge by perceptual experience, noalternative account of Cartesian scepticism has been offered. Butperhaps they need not.5

Our thoughts on why scepticism is a problem are relevant here.An advantage of understanding Cartesian scepticism as focused onunderdetermination problems is that this account shows how we arethreatened with radical scepticism. But there is a disadvantage too:it is not at all obvious that sceptical arguments from underdetermin-ation are genuinely intuitive. The sceptic reaches his conclusion byplacing us under epistemic disabilities that do not flow in any clearway from how knowledge and justification are ordinarily under-stood. The sceptic challenges us to rule out his bizarre hypotheseson the basis of experiential evidence alone. Even supposing that heis correct in claiming that we cannot do this, it is not clear thatthis is problem. We need to be shown that the sceptic’s demand issomething that we are ourselves rationally committed to.

This thought reinforces the need, felt by contextualists like Lewisand DeRose, to find a simpler, less theoretically loaded way ofposing Cartesian problems. However, turning away from underde-termination problems, focusing on the argument from ignorance,and characterising sceptical hypotheses as “remote” possibilitiesthat do not normally need to be ruled out, itself threatens toexact a heavy cost. This is that, by understanding scepticism inthese terms, contextualists like Lewis and DeRose seem to restrictthemselvesab initio to an uninteresting high standard- or evencertainty-scepticism.6


To the extent that the Argument from Ignorance does not dependon undetermination problems, it surely invokes a conception ofknowledge that makes knowledge hostage to our ability to elim-inate of all logically possible (as opposed to all commonsensicallyrelevant) defeaters. Lewis is quite explicit about this. The scepticalargument, he says, is just that

it seems as if knowledge must be definition infallible. If you claim that S knowsthat P, and yet you grant that S cannot eliminate a certain possibility in which not-P, it certainly seems that you have granted that S does not after all know that P.To speak of fallible knowledge, of knowledge despite uneliminated possibilitiesof error, justsoundscontradictory (419, emphasis in original).

Now even assuming that we have infallibilist intuitions, it is notobvious that they should be taken seriously. Maybe they are justleftovers from a discarded ideal of certainty. But let this go. Letus agree that we should take our “infallibilist” intuitions seriously:what follows? Scepticism, because ordinary knowledge simply isn’tinfallible? According to Lewis, no. By allowing shifting standardsfor fallibility, SCC offers a way out of the dilemma between “falli-bilism” and “scepticism.” But why is this dilemma worth worryingabout? Lewis’s “fallibilism” is the doctrine thatknowledgemightbe fallible: whereas what is ordinarily thought of as fallibilismis a doctrine about justification. And not justification narrowlyconceived, but our epistemic resources generally. It is the view that,even when we are on our best behaviour epistemically speaking,we can never entirely exclude the possibility that the results weare led to may need revision. As for the “infallibility” that leads toscepticism, it makes knowledge depend on eliminating all logicallypossible ways of going wrong. So Lewis’s scepticism is just the viewthat this cannot be done. In other words, Lewis’s “scepticism” isjust fallibilism as it ought to be understood. If SCC offers no morethan an escape from Lewis’s dilemma, it cannot be diagnosticallyadequate to the scepticism that really ought to trouble us. It is noteven addressed to the right problem.

Now some readers may have suspected for a while that my insist-ence that scepticism be radical is itself tantamount to a refusalto take externalist SCC seriously. An externalist will surely wantto claim that, if we can detach knowledge from justification andstill show how knowledge is possible, we can drain the interest

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from radical scepticism and the justification-centered arguments onwhich it depends. Of course, we will still have to deal with anyforms of knowledge-specific scepticism that threaten to arise fornon-justificational anlayses of knowledge. But knowledge-specificscepticism, not radical scepticism, will be the interesting problem.

Matters are not so simple. For one thing, as we shall see, it isfar from clear that any version of SCC offers a purely externalistaccount of knowledge (although, as we shall also see, advocates ofexternalist SCC are far from clear about this). But there are othercomplications to take into account.

It is true that an externalist who takes no interest in justification,if he is concerned with scepticism at all, will be concerned withit only in some knowledge-specific form. However, this does notpreclude an interest in radical scepticism. The general contrast isbetween radical scepticism and high-standards high-standards scep-ticism, not radical scepticism and knowledge-specific scepticism.For a justificationist about knowledge, who takes Gettier’s problemseriously, knowledge-specific scepticism is inevitably a form ofhigh-standards scepticism. For an externalist, at least an externalistwho is also a contextualist, this need not be so. Such an exter-nalist will insist that epistemic standards – however understood –are variable. In particular, they are much less severe in everydaysituations than in the context of philosophical reflection or of “doingepistemology.” This makes conceptual room for radical scepticism:the sceptic has only to argue that knowledge fails even by everyday,relaxed standards. If successful, the sceptic will erase all epistemicdistinctions, even if they are explained in the externalist contex-tualist’s non-justificational terms. This means that the externalistproponent of SCC must have something to say about radical scep-ticism after all. SCC must be developed in a way thatsuccessfullyinsulates everyday knowledge-claims from sceptical undermining.

The possibility of combining externalism with contextualismcomplicates the picture in another way. Once contextualism isin play, high-standards scepticism can become interesting as thediagnostic key to radical scepticism. The advocate of SCC canargue that the sceptic’s pretended radical scepticism is itself high-standards scepticism in disguise. Drawing on his account of the vari-ability of epistemic standards, he can claim that we will suspect that


knowledge fails in ordinary circumstances only if we mistakenlyconflate ordinary standards with the artificially high standardsinduced by “doing epistemology.”7 So we have a diagnosis ofradical scepticism that SCC needs anyway: the sceptic imports thesevere standards appropriate to doing epistemology into ordinarycontexts of epistemic appraisal. Scepticism, so to say, is always highstandards scepticism, though an illusion of radical scepticism can beproduced by reading inappropriately high standards into everydaysituations.

5. JUSTIFICATION: TWO ASPECTS

Let us now look more closely at Lewis’s case for the “elusiveness”of knowledge.

For Lewis, knowledge is infallible in the following sense: Sknows that P if and only if S’s evidence for P eliminates everypossibility in which P is false. However, what counts as “every”possibility varies with context. Thus the standards for “infallib-ility” also vary: they are more severe in some contexts than others.Depending on turns in the conversation or someone’s train ofthought, the range of error-possibilities in play expands or contracts,moving us between more an less demanding epistemic contexts. Sknows that P if and only if S’s evidence eliminates every currentlyconversationally relevant or appropriate error-possibility. Since ourevidence may eliminate all error-possibilities in play in one contextbut not all those in play in another, knowledge is elusive: it comesand goes.

Context-shifts – the expansion and contraction of the rangeof relevant error-possibilities – occur in accordance with rulesgoverning conversational presuppositions. Wepresupposepropos-ition Q iff we ignore all possibilities in which not Q; equivalently,we ignorewhatever possibilities falsify our presuppositions. But wecan’t presuppose, or ignore, whatever we like: that would makeknowledge too easy to obtain. The rules in question are rules ofproperpresupposition orproperignoring. Knowledge is thus subjectto what Lewis calls “thesotto voceproviso”: S knows that P iff S’sevidence eliminates every possibility in which not P – Psst, exceptfor those possibilities that conflict with our proper presuppositions

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(426). I take it that the proviso issotto vocebecause an explicitrelativisation to context is not (intuitively) part of the content of aneveryday knowledge-claim. This seems right.

Some presupposition-rules are prohibitive: they tell us whichpossibilities maynot be left uneliminated, if we are to have know-ledge. For example:

Rule of Belief. A possibility that the subject believes to obtain is not properlyignored, whether or not he is right to do so. Neither is one that he ought to believeto obtain – one that evidence and arguments justify him in believing – whether ornot he does so believe. (428)

Other are permissive. For example, aRule of Conservatismallowsus, defeasibly, to adopt the usually and mutually expected presup-positions of those around us. It allows us to ignore what they ignore,unless other rules force some commonly ignored possibility on ourattention.

Now Lewis presents this account of knowledge as non-justificational. In Lewis’s view, justification is neither sufficient nornecessary for knowledge. But Lewis’s account of knowledge ismuch less purely non-justificational than he thinks.

Lewis ties knowledge to the elimination of error-possibilities by“evidence.” However, he understands both “evidence” and “elim-ination” is a fully externalist way. When perceptual experience,Lewis’s paradigm of evidence, eliminates a possibility, W, this is“not because the propositional content of the experience conflictswith W . . . Rather, it is the existence of the experience that conflictswith W: W is a possibility in which the subject is not having exper-ience E” (422).8 In general, a possibility W is uneliminated iff thesubject’s perception and memory in W exactly match his perceptualexperience and memory. If there is no such match, W is eliminated.The subject’s evidence thus eliminates W whether or not he is awarethat it does. Lewis’s appeal to evidence, then, does not by itselfintroduce an obviously justificational dimension into his account ofknowledge. But his presupposition-rules do.

As Hilary Kornblith and Robert Fogelin have argued, justifica-tion has two aspects, both of which are involved in knowledge.9

One aspect – the procedural aspect – concerns epistemic responsi-bility: to be justified in holding a particular belief, a person musthave formed it, or be retaining it, in an epistemically respon-


sible way. Lewis’s presupposition-rules are clearly concerned withjustification in this sense: they are normative principles governingthe possibilities that a person mayproperly – i.e. responsibly –ignore. Notice, here, how strong a normative constraint the Ruleof Belief imposes: one may not ignore possibilities arising fromwhat one ought to believe, whether or not one actually does believeit. Imposing such a constraint would be unintelligible unless werecognised justification, in the sense of epistemic responsibility, asnecessary for knowledge. But as we have noted, and as Lewis insists,if knowledge were not subject to such normative constraints – if wecould fix byfiat the possibilities that our evidence must eliminate –we could presuppose our way into knowing anything we liked. Wewould lose any sense of knowledge’s being a positive or desirableepistemic state.

The second aspect of justification has to do with the subject’sgrounds, which must be objectively adequate if he is to haveknowledge. Now Fogelin happily concedes that, insomecases, evid-ence is best understood along externalist lines. So unless Lewisthinks that the elimination of error-possibilities by the propositionalcontent of a person’s evidence isnever relevant to his knowingpossessing knowledge, Lewis’s “non-justificationalist” account ofknowledge is identical with Fogelin’s justificationist analysis. ButLewis cannot think anything of the sort: his rules stand in theway. Once it is conceded that sometimes error-possibilities cannotbe ignored because their relevance has been have been conceded– which the Rule of Belief certainly implies – they cannot beeliminated in a purely externalist way.

Suppose you accuse me of improperly ignoring an error-possibility, W. I cannot reply: “Maybe I’m not ignoring it; maybemy total current perceptual/memory state (whatever it is) would bedifferent if W were to obtain; so I may have knowledge, thoughI don’t know whether I do.” To allow this reply would be to letgo of the idea of epistemic responsibility – hence the need forrules anything like those Lewis proposes – altogether. When error-possibilities are in play because consciously recognised, they mustbe evidently eliminated by the evidence at one’s disposal, not justeliminatedde facto. The admission that justification, in the sense of

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epistemic responsibility, is required for knowledge limits the extentto which one can be an externalist with respect to evidence.

Lewis, however, fails to keep the normative character of hisrules, hence the justificational element in his account of knowledge,consistently in view. Or perhaps it would be better to say, that otheraspects of his position – which are integral components of SCC –prevent him from so doing. Seeing why, exposes the limits of SCC’sdiagnostic power.

6. HOW ELUSIVE IS KNOWLEDGE?

The final standard-setting rule that Lewis introduces is theRule ofAttention:

When we say that a possibilityis properly ignored, we mean exactly that; we donot mean that itcould have beenproperly ignored. Accordingly, a possibility thatis not ignored at all isipso factonot properly ignored. (559, emphasis in original.)

Lewis calls this “more a triviality than a rule” (434). But it is the keyto his position. And it is anything but trivial.

One result of adopting the Rule of Attention is that Lewis canexplain away apparent cases of failure of epistemic closure. Theproposition that I have hands implies that I am not a brain in a vat.So by closure, if I know that I have hands, then I know that I am nota brain in a vat. But I don’t know that I am not a brain in a vat: whatcould eliminate that possibility? So bymodus tollens, I don’t knowthat I am not a brain in a vat. It seems that, if we agree that scepticalhypotheses cannot be eliminated by evidence, but want to hold onto everyday knowledge, denying closure is our only hope. But itisn’t. Wild sceptical hypotheses are properly ignored in ordinarycircumstances, with he result that our evidence need not eliminatethem. But if we try to draw explicit anti-sceptical conclusions fromcorrect everyday knowledge-claims, the Rule of Attention effectsa presupposition shift, creating a context in which sceptical hypo-theses are no longer properly ignored. This presupposition-shiftcreates an apparent failure of closure: you know things at the startof the argument that you (temporarily) don’t know at the end.

This is plausible. Nevertheless, there is something fishy aboutthe Rule of Attention. Lewis’s rules are introduced to prevent our


obtaining knowledge too easily. But the Rule of Attention makesretaining knowledge too hard. Conceding for the present that far-fetched sceptical possibilities – brains-in-vats, demon-deceivers –resist elimination by evidence, the Rule ensures that a person’sknowledge vanishes every time such a possibility enters his head.Although the point of introducing presupposition-rules was toprevent knowledge-by-fiat, the Rule of Attention provides for ignor-ance at will. This is a striking asymmetry.

Lewis is aware that the thought that the mere mention of apossibility makes it epistemically relevant has counter-intuitiveconsequences. He imagines two epistemologists off on a hike,imagining all sorts of wild error-possibilities, thus knowing nothing.But they don’t get lost, which seems to mean that they retain a gooddeal of knowledge. Lewis suggests that a person’s thinking may becompartmentalised, the philosophy compartment attending to scep-tical scenarios, the navigation compartment ignoring them. Whatthen does a person know? Lewis thinks this question is not feli-citous, which it isn’t if compartmentalisation relativizes knowledgeto context. One knows for the purposes of navigation that one hasreached the top of the hill; for the purposes of doing epistemologyone does not know any such thing: there is nothing that one knowssimpliciter.

Now Lewis is clearly not altogether happy with this position.Indeed (recall thesotto voceproviso), his contextualism was origin-ally structured so as to avoid the explicit relativisation of knowledgeto context. He is therefore reluctant simply to refuse to answer thequestion about what a person knowssimpliciter. If this question hasto be answered, he suggests, the best answer is that a person knowsthat P iff one of his compartments does (443). But if we accept thisanswer, we are in danger of losing the elusiveness of knowledgeand, with it, the diagnosis of scepticism. Doing epistemology nowthreatens only knowledge-in-a-compartment. Knowledgesimpli-citer is safe as long as there is knowledge in some compartmentor other. The best we can do, by way of diagnosis, is to say thatthe sceptic confuses knowledge-in-a-compartment with knowledgesimpliciter. But this is plausible only if we agree that we havetwo notions of knowledge, relative and non-relative. Moreover, thestrategy of relativization threatens to play into the sceptic’s hands.

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What compartmentalisation really shows, the sceptic may say, isthat, while we have all sorts of knowledge-for-this-or-that practicalpurpose, we never have knowledgesimpliciter. This follows fromour failure to command knowledge in the context of doing epistem-ology, which differs from other contexts precisely by prescindingfrom all particular practical purposes. Something has gone wrong.What?

One clear defect in the Rule of Attention is that it wronglyequates ignoring something not being aware of it. If (rudely or quiteunderstandably) I ignore you at a party, this is not because I don’trealise you are there. On the contrary, I have to know you are there toignore you. So too in epistemic matters. I can (properly or improp-erly) ignore – i.e. not take into account – possibilities of which Iam fully aware. Lewis forgets the normative character of his rules.The psychological fact ofnoticing a possibility does not settle thenormative question of whether itdeserves notice. Purged of confu-sion, theRule of Attentionstipulates that no consciously recognizedpossibility may properly be ignored. But why should anyone acceptthis?

In fact, Lewis has a reason. Because, like all advocates of SCC,he thinks of sceptical hypotheses as bizarre or remote possibilitieswhich are, nevertheless, constructed so as to be beyond evidence,pro or contra, he has no way of explainingwhy they might deservenotice. In this way, sceptical possibilities are quite unlike everydayknowledge-defeaters. My worries about the train timetable, if theyare not just neurotic, are triggered: either economically by the costsof error (I just have to make that interview), or informationally (Iheard something about track repairs on the local news). But in thecontext of “doing epistemology,” practical interests are beside thepoint and informational triggers out of the question. So in order tosay why sceptical hypotheses may not properly be ignored in thecontext of “doing epistemology,” the site of the sceptic’s somewhathollow victory, Lewismusthold thatmerely thinkingof such possi-bilities turns them into relevant alternatives.10 The Rule of Attentionis an inevitable consequence of Lewis’s – which is SCC’s – concep-tion of doing epistemology. This suggests that there is somethingamiss with that conception.


I see no reason to accept the Rule of Attention, no reason to fallin with Lewis’s attenuated conception of doing epistemology, andso no reason to accept the elusiveness of knowledge. But even if weaccept all these things, we are led to nothing more than a bloodlesshigh-standards scepticism, which need not perturb us.

7. RADICAL SCEPTICISM AGAIN

We are not yet out of the woods. To see why, we have to look atthree further Rules, two prohibitive and one permissive:

• Rule of Actuality. The possibility that actually obtains is neverproperly ignored; actuality is always a relevant alternative;nothing false may be presupposed. (426)

• Rule of Resemblance. Suppose one possibility salientlyresembles another. Then if one of them may not properly beignored, neither may the other. (429)

• Rule of Reliability. [P]rocesses whereby information is trans-mitted to us. . ., perception, memory and testimony. . ., arefairly reliable . . . We may properly presuppose that they workwithout a glitch in the case under consideration. (432)

All are important. Actuality and Resemblance solve the Gettierproblem. Reliability captures “what is right about causal or reli-abilist theories of knowing” (432). In my terms, it is Lewis’s(externalist) answer to Agrippan scepticism.

In a Gettier case, I form a true belief that P on the basis ofevidence, E, that is a normally reliable indicator of the truth of P,so my belief is also justified. But in the special circumstances of aGettier case, P is true for reasons that have nothing to do with E.In accepting P on the basis of E, I ignore possibilities in which Eis available even though P is false. Since, depending on the detailsof the case, these possibilities will resemble actuality in varioussalient ways, they are ignored improperly, so that my belief doesnot amount to knowledge.

ActualityandResemblancepermit Lewis to handle Gettier casesby giving him a way to capture the idea of good but circumstan-tially misleading evidence. The trouble is that, without some wayof restricting their application, they get out of hand. According toLewis:

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. . . it is possible to hallucinate – even to hallucinate in such a way that all myperceptual experience and memory would be just as they actually are. That possi-bility can never be eliminated. But is can be ignored. And if it is properly ignored– as it mostly is – then vision gives me knowledge. (423)

The problem, as Lewis notes with admirable candour, is that “actu-ality is a possibility uneliminated by the subject’s evidence” (430).So if I am a victim of demon-deception, I am always improperlyignoring this possibility:ActualitydefeatsReliability. Here we havea powerful form of meta-scepticism. But this is not all:

Any other possibility W that is. . . uneliminated by the subject’s evidence therebyresembles actuality in one salient respect: namely, in respect of the subject’s evid-ence. That will be so even if W is in other respects very dissimilar to actuality –even if, for instance, it is a possibility in which the subject is radically deceivedby a demon. Plainly, we dare not apply the Rules of Actuality and Resemblanceto conclude that any such W is a relevant alternative – that would be capitulationto scepticism. (430)

Lewis says that we seem to have anad hocexception to the Rule ofResemblance. Clearly, it would better to reformulate the Rule so asto avoidad hocexceptions but, again with admirable candour, Lewissays that he does not see how.

Notice the strikingly different attitude Lewis takes toAttentionand Resemblance. The former Rule iswelcomedfor its power todestroy knowledge. Indeed, Lewis explicitly repudiates attempts torestrict it in ways that would limit its sceptical potential. The latteris treated in exactly the opposite way: its sceptical potential must belimited, even at the cost of a restriction that is completelyad hoc.But perhaps even more striking is the fact that Lewis does not evenattempt to appeal to his contextualism to resolve the problem, eventhough the virtue of contextualism is supposedly its power to put thesceptic in his place.

The reason for all this is exactly what I have been suggesting allalong. Lewis’s contextualism generates and handles only an unin-teresting form of high standards scepticism. This scepticism canbe handled by “variable standards” contextualism (SCC) preciselybecause it arises only in contexts where unusually high standardsare in force. By contrast, the scepticism threatened by the Rules ofActuality and Resemblance is not contextually bounded in this way.If it arises at all, it arises in even the most ordinary contexts: it is, in


fact, radical scepticism, as that problem arises within an externalistapproach to knowledge. Lewis must repudiate radical scepticismprecisely because it is a problem that a diagnosis tailored to highstandards scepticism cannot handle.

I said earlier that focusing on high standards scepticism mightstill provide they key to radical scepticism if it could be shownthat the threat of radical scepticism is an illusion, arising fromillicitly importing the high standards appropriate to “doing epistem-ology” into ordinary acceptance-contexts. But it should be clear that,without an explanation of thead hocexception to Resemblance,there is no way of saying whether or not this line of defence is evenavailable to Lewis. The effect of the Rule of Resemblance, in itsunrestricted form, is that even the remotest defeaters are improperlyignored in even the most ordinary contexts. In other words, the Ruleobliterates the idea of contextually variable standards. Accordingly,everythingdepends on how the exception is explained. Once more,a sceptic might say that we ignore certain resemblances, thus certainrelevant possibilities, forpractical purposes. But we never haveknowledge, or even epistemically (as opposed to practically) justi-fied belief. Because such explanations must be ruled out, if we areto make any progress against scepticism, explaining the exceptionisn’t a supplement to a diagnosis of scepticism: it is the diagnosis.

I began by discussing two ways that arguments for Cartesianscepticism might be supposed to arise. One located the signifi-cance of sceptical hypotheses within a range of underdeterminationproblems. The other made them crucial components of the argu-ment from ignorance. The problem was that underdeterminationscepticism, while unquestionably radical, was dubiously intuitive.Argument-from-ignorance scepticism, by contrast, while less theo-retically loaded, seemed to amount to no more than an uninterestinghigh-standards or certainty-scepticism.

We have confirmed these suspicions. Unmodified, the Rule ofResemblance combines with the Rule of Actuality to generateundetermination problems: that is how these Rules threaten Lewiswith radical scepticism. Demon worlds resemble actuality in respectof the evidence at our disposal. This resemblance is so striking thatit seems ad hoc and totally unsatisfactory simply to dismiss its rele-vance. But Lewis’s contextualism suggests no other course, since is

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tailored to the high-standards scepticism generated by the Rule ofAttention.

8. REMOTE POSSIBILITIES

The critical source of Lewis’s difficulties is his lack of clarity aboutthe normative-justificational dimension of his account of know-ledge. In stating the Rule of Resemblance, Lewis once more elidesthe distinction between the psychological and the normative. Here,the vehicle this elision is the notion of “salience,” which remainsnicely poised between the psychologically striking and the epistem-ologically significant. Purged of ambiguity, the Rule of Attentionamounted to the implausible constraint that anythingnoticed isdeserving of notice. Comparably purged, the Rule of Resemblancemakes the same claim on behalf of whatever isnoticeable. Orrather it would do so, ifad hocexceptions were not imposed. Theinadequacies of the Rules are thus mirror-images. For no apparentreason, mere notice can destroy knowledge. But also for no apparentreason, mere noticeability cannot.

The question is: does contextualism of the kind Lewis defendshave the resources to repair these deficiencies? I do not think thatit does. The diagnostic limitations of Lewis’s epistemology are notan idiosyncratic feature: they are inherent in the general approach toknowledge that I have called “simple conversational contextualism.”

The high-standards scepticism that this approach can handleis closely linked to SCC’s conversational or dialectical character.Error-possibilities become relevant simply by being brought up or,more generally, attended to. When they return to the unspokenbackground, they cease to be relevant. Conversational contextu-alism lets knowledge disappear and reappear, in exactly the sameway. However, the radical scepticism threatened by the Rules ofResemblance and Actuality has nothing to do with conversationalfactors. It arises out of the similarity between our epistemic situ-ation in the actual world and our epistemic situation in worldsinvolving massive deception. It is this fundamental similarity, notthe vagaries of conversation or attention, that poses the problem.Indeed, so far as the resources of conversational contextualism areconcerned, this similarity is an invariant feature of our epistemic


position. Result: no version of contextualism that limits its concep-tion of context-shifting to conversational considerations will be ableto handle it.

The second limitation of SCC is its simplicity. SCC postulates asimple scale of standards for knowledge, from lax to severe, withseverity as a function of the range of defeaters in play. The more“remote” the defeaters deemed relevant, the higher the standardsfor knowledge. However, there is no such simple scale of severitybecause there is more than one way of being remote. The idea of“remoteness” involved in the high-standards scepticism associatedwith the Rule of Attention is the commonsense idea offactualremoteness: sceptical possibilities represent worlds in which mostof what we ordinarily believe is false. But according to the sceptic,while such worlds are factually remote (that is the point) they areepistemically close. So recognising this is not a matter of imposinghigher than normal standards. It is just a matter of recognising thefix we are always in.

Of course, this could be questioned: are the ways of knowingavailable in normal and demon worlds really the same? Howshould ways of knowing be individuated? These are good questions,but following them up would take us far beyond the theoreticalresources of SCC.

Let me indicate very briefly how I think they should be followedup. The place to begin is with the idea of the special context createdby “doing epistemology.” There is something right in the idea that“doing epistemology” involves a distinctively unrestricted exam-ination of our claims to knowledge. But this special character isnot captured by the admissibility of arbitrarily far-fetched error-possibilities, which become relevant simply by being noticed. Onthe contrary, the admissibility of sceptical hypotheses does notdefine the context of doing epistemology. It is doing epistemologythat makes sceptical hypotheses seem relevant.

The sceptic, as I understand him, wants to ask certain highlygeneral questions about human knowledge. For example, he wantsto know how it is, or why we are entitled to suppose, that we knowanything whatsoever about the external world. The key feature of“sceptical” error-possibilities, therefore, is not that they areremotebut that they aregeneric. The thought that I might be a brain in a vat

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defeats every claim to knowledge of the external world, if it defeatsany.11

Back to epistemology. If the legitimacy of sceptical defeaters isclosely tied to the methodological demands of a particular theo-retical project, the context of appraisal created by “doing epistem-ology” involves more than raising standards, ratcheting up whatRobert Fogelin nicely calls “the level of scrutiny.” In a very realway, it involves changing the subject: theangleof scrutiny. A phys-icist can raise indefinitely the level of scrutiny to which the resultsof a particular experiment are subject, repeating the experimentunder ever more stringently controlled conditions. But if he startswondering whether he is a brain in a vat, this will not inaugurate aneven more scrupulous approach to his research: rather, the intro-duction of the generic defeater submerges the given inquiry in acompletely different kind of investigation.

Only if we concede the legitimacy of this distinctively generalexamination of knowledge do generic defeaters exert a normativeclaim on our attention. Accordingly, subjecting this traditionalphilosophical project to a close critical examination is the strategyI recommend. Following it through leads to a version of contex-tualism which is considerably more complex than SCC12. SCCis a shallow contextualism. It cannot cope with deep forms ofscepticism.

NOTES

1 Versions of this paper were given at a conference “New Directions in Epistem-ology,” held at the University of Tuebingen, January 1999, and the 1999 OberlinColloquium. I want to thank the participants in those conferences for muchstimulating discussions, but especially Stewart Cohen, Fred Dretske, ThomasGrundmann, Hilary Kornblith, Bill Lycan, Karsten Stueber and my commentatorat Oberlin, Tim Williamson.2 See e.g. Stewart Cohen, “Knowledge, Context and Social Standards,”Synthese73 (1987), pp. 3–26. Lewis’ original hint is found in David Lewis, “Score-keeping in a Language Game,” in Lewis,Philosophical Papers, vol 1 (Oxford:Oxford University Press 1983). Lewis gives a detailed discussion of knowledgeand scepticism in “Elusive Knowledge,”Australasian Journal of Philosophy74(1996), pp. 549–567; reprinted in Lewis,Papers in Metaphysics and Epistemology(Cambridge: Cambridge University Press, 1999); subsequent references are to thisreprinting and are given in the main text by page numbers in parentheses. Keith


DeRose offers an intricate development of non-justificationist contextualism in“Solving the Skeptical Problem,”Philosophical Review104 (1995), pp. 8–51. Ihope to discuss DeRose’s views in detail on another occasion.3 Robert Fogelin,Pyrrhonian Reflections on Knowledge and Justification(Oxford, Oxford University Press 1994). I should note, however, that Fogelin isless straightforwardly anti-sceptical than the others, using contextualist ideas toargue for the correctness, or at least irrefutability, of a certain kind of scepticism.4 Lewis takes the first option, DeRose the second.5 For a defence of the view that underdetermination is the key to Cartesianscepticism, see Anthony Brueckner, “The Structure of the Skeptical Argument,”Philosophy and Phenomenological Research, LIV (1994). Stewart Cohen repliesto Brueckner in “Two Kinds of Skeptical Argument,” Ibid., LVIII (1998).6 I owe the phrase “high standards” scepticism to Hilary Kornblith, whopresented a powerful critique of DeRose’s contextualism at the 11th AnnualSOFIA conference, University of Oviedo, June 1998.7 This reply was suggested to me by Stewart Cohen.8 This is, in effect, Dretske’s (externalist) notion of a conclusive reason: E isa conclusive reason for P in the sense that, if P were false, S would not haveexperience E. See Fred Dretske, “Conclusive Reasons,”Australasian Journal ofPhilosophy29 (1971), pp. 1–22.9 Hilary Kornblith, “Ever Since Descartes,”The Monist68 (1985), pp. 264–276.Fogelin, op. cit., ch. 1.10 He is not alone in this: for example, Fogelin also holds that the “level of scru-tiny” to which knowledge-claims are subject can be “raised by reflection alone.”SeePyrrhonian Reflections, p. 93ff.11 Michael Williams,Unnatural Doubts: Epistemological Realism and the Basisof Scepticism(Oxford, Blackwell 1992; paperback edition, Princeton N.J., Prin-ceton University Press 1996).12 I give further details inProblems of Knowledge(Oxford: Oxford UniversityPress, forthcoming).

Department of Philosophy347 Gilman HallJohn Hopkins UniversityBaltimore, MD 21218, USA

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Contextualism, Externalism and Epistemic Standards