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Knowledge and Reality Scepticism Lecture three: Epistemic Contextualism. Ema Sullivan-Bissett Feedback and Advice hour: Thursdays, 11:30, office A/101 (weeks 2–6). A (very brief) recap. The Sceptic’s Challenge.

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knowledge and reality scepticism lecture three epistemic contextualism

Knowledge and RealityScepticismLecture three: Epistemic Contextualism

Ema Sullivan-Bissett

Feedback and Advice hour: Thursdays, 11:30, office A/101

(weeks 2–6)

the sceptic s challenge
The Sceptic’s Challenge
  • The Sceptical Argument

(S1) I do not know that I am not a brain in a vat.

(S2) If I do not know that I am not a brain in a vat then I do not know that I have two hands.

(SC) I do not know that I have two hands.

  • The Sceptical Paradox
    • I know that I have two hands.
    • I do not know that I’m not a brain in a vat.
    • If I do not know that I’m not a brain in a vat, then I do not know that I have two hands.

(adapted from Pritchard 2002: 217)

two dogmatic responses
Two Dogmatic Responses
  • Perceptual Knowledge (Moore 1959): I know that I have two hands, and so I know that I’m not a brain in a vat.
  • Perceptual Justification (Pryor 2002): I don’t know that I have two hands, but absent any defeaters, I have immediate prima facie justification for believing that I have two hands on the basis of perceiving that I have two hands.
changing contexts dinner party case
Changing Contexts:Dinner Party Case
  • One seat with little leg room. I ask you whether Michael is tall. You say he is 6’5”, we agree that:
    • Michael is tall.

(Feldman 1999: 92).

changing contexts basketball case
Changing Contexts: Basketball Case
  • After dinner, we discuss whether Michael could make it as a basketball player. You say he could only play centre but players in that position are typically 7’ tall. We agree that:

2. It is not the case that Michael is tall.

(Feldman 1999: 92).

Michael is tall.
    • It is not the case that Michael is tall.
  • I was right when I asserted 1, and I was right when I asserted 2:

‘[W]hether the word 'tall' applies to an object depends in part upon facts about the context of attribution. When someone predicates 'tall' of something, there is typically a contextually determined standard for the application of the term. The person's claim is true if and only if the object designated meets that standard’

(Feldman 1999: 92).

changing contexts for knowledge
Changing Contexts for Knowledge

‘What it takes for a knowledge sentence to be true can vary from context to context; sometimes the standards are more restrictive, sometimes more liberal. The key point is that the relation a person must bear to a proposition in order for it to be correct to say that the person knows the proposition changes according to context’

(Feldman 1999: 93).

changing standards for knowledge
Changing Standards for Knowledge
  • Our standards for knowledge change across contexts.

‘In some contexts, when we use the word ‘know’, we have low standards of knowledge in mind: standards that are easy to meet. We will then ascribe knowledge liberally. In other contexts, our use of the word ‘know’ is guided by more demanding high standards. Meeting these is very difficult. In such contexts, we will ascribe knowledge only reluctantly’

(Steup 2005).

an example
An Example

‘Consider: you ask me whether I know when the next train leaves for the city and I tell you “Yes, two o’ clock.” Imagine that I have I have derived my information from an impeccable source, such as the latest timetable, so that it seems clear that I really do know. However, you explain that you have an appointment that you absolutely cannot miss. Moreover, it does happen occasionally that repairs to the track require temporary timetable changes. Have I looked into whether any such changes have been announced for today? No. So do I really know that the next train leaves at two? Suddenly, things seem less clear’

[sic] (Williams 2001: 1–2).

  • The Closure Principle: ‘If I know that p, and I know that p entails q, then I know that q’ (Steup 2005).
  • Suppose you’re in the Willow. Your being in the Willow entails your not being in Bier Keller. If you know both of these things, then you know that you’re not in Bier Keller.
  • Closure and the sceptical argument:

P: I am giving a lecture

Q: I am not a brain-in-a-vat.

  • Brain-in-a-vat closure: If I know that I am giving a lecture, and I know that if I am giving a lecture then I am not a brain in a vat, then I also know that I’m not a brain in a vat.
  • (Notice: denying closure is a way out of scepticism, see Dretske 1970.)
solving the paradox
Solving the Paradox
  • I know that I have two hands.
  • I do not know that I’m not a brain in a vat.
  • If I do not know that I’m not a brain in a vat, then I do not know that I have two hands.

(adapted from Pritchard 2002: 217)

The solution:

  • In ordinary, low standard contexts, 1 and 3 are true, but, by modus tollens, 2 is false. In sceptical, high standard contexts, 2 and 3 are true, but, by modus ponens, 1 is false. The paradox is resolved.
responding to the argument
Responding to the Argument

(S1) I do not know that I am not a brain in a vat.

(S2) If I do not know that I am not a brain in a vat then I do not know that I have two hands.

(SC) I do not know that I have two hands.

  • In ordinary, low standard contexts, premise (S1), by modus tollens is false (since the conclusion is false because we meet the low standards for knowledge). In sceptical, high standard contexts, premises (S1) and (S2) are true, and therefore, by modus ponens, so is the conclusion.
the contextualist response in brief
The Contextualist Response: In Brief

‘The problem of skepticism lies in the conflict between skepticism and everyday epistemic attitudes: skeptical reasoning (at its best) is flawless, compelling, and thus rationally undeniable; but the skeptical conclusion is absolutely implausible, even ridiculous, from an “ordinary” perspective. An adequate response to skepticism should explain how the knowledge claims we make in everyday life can be true, even though, in some sense, skepticism is correct. Initially, that seems impossible: if A and B oppose one another, how could we show that A is correct without denying B? The contextualist response is that, although A and B appear to oppose one another, they really do not. Skepticism and “ordinary” knowledge claims belong to different kinds of epistemic contexts, so that although skepticism is correct relative to the standards of knowing operative in its own context, it has no bearing on knowledge claims made in “ordinary” contexts, where different standards for knowledge operate’

(Daukas 2002: 63–4).

we know a lot
‘We know a lot’

‘We know a lot. I know what food penguins eat. I know that phones used to ring, but nowadays squeal, when someone calls up. I know that Essendon won the 1993 Grand Final. I know that here is a hand, and here is another’

(Lewis 1996: 549).

‘Besides knowing a lot that is everyday and trite, I myself think that we know a lot that is interesting and esoteric and controversial. We know a lot about things unseen: tiny particles and pervasive fields, not to mention one another’s underwear. Sometimes we even know what an author meant by his writings’

(Lewis 1996: 549).

we know next to nothing
‘We know next to nothing’

‘For no sooner do we engage in epistemology […] than we meet a compelling argument that we know next to nothing. The sceptical argument is nothing new or fancy. It is just this: it seems as if knowledge must be by definition infallible. If you claim that S knows that P, and yet you grant that S cannot eliminate a certain possibility in which not-P, it certainly seems as if you have granted that S does not after all know that P. […] Those possibilities of error are far-fetched, of course, but possibilities all the same. They bite into even our most everyday knowledge. We never have infallible knowledge’

(Lewis 1996: 549).


‘Subject S knows proposition P iff P holds in every possibility left uneliminated by S’s evidence; equivalently, iff S’s evidence eliminates every possibility in which not-P’

(Lewis 1996: 551).

eliminating possibilities
Eliminating Possibilities
  • Uneliminated possibilities are the ones in which the subject’s perceptual experience and memory are as they are in actuality:

‘[A] possibility W is uneliminated iff the subject’s perceptual experience and memory in W exactly match his perceptual experience and memory in actuality’

(Lewis 1996: 553).

possibilities and domains
Possibilities and Domains
  • Looking around the lecture theatre I say ‘Everyone looks tired’.
  • When I say that I – and my audience – ignore all of the people in the world that aren’t currently in the lecture theatre.
  • Those people are outside of the domain to which my claim was restricted, and so ‘are irrelevant to the truth of what was said’ (Lewis 1996: 553).
proper ignoring
Proper Ignoring
  • New definition of knowledge:

‘S knows that P iff S’s evidence eliminates every possibility in which not-P […] except for those possibilities which we are properly ignoring’

(Lewis 1996: 554).

  • What can be properly ignored?

‘[O]f course, I am not entitled to ignore just any possibility I please’

(Lewis 1996: 554).

compare flat surface
Compare: Flat Surface

‘Just as P is known iff there are no uneliminated possibilities of error, so likewise a surface is flat iff there are no bumps on it. We must add the proviso: Psst! – except for those bumps that we are properly ignoring. Else we will conclude, absurdly, that nothing is flat’

(Lewis 1996: 554).

but first possible worlds

Possible world two

Possible world three

Possible world one

Actual world

Impossible world

But First: Possible Worlds

ES-B is giving a lecture at 16:00 on 21/10/14 stood on her head with a live chicken sticking out of her nose.

ES-B is giving a lecture at 15:00 on 21/10/14


ES-B is giving a lecture at 16:00 on 21/10/14 stood on her head.

ES-B is giving a lecture at 16:00 on 21/10/14

ES-B is giving a lecture at 16:00 on 21/10/14 and ES-B is not giving a lecture at 16:00 on 21/10/14.

rule of actuality
Rule of Actuality
  • ‘The possibility that actually obtains is never properly ignored’ (Lewis 1996: 554).
  • What is actual is always a relevant alternative.
  • Whose actuality is important?

‘There is just one actual world, we the ascribers live in that world, the subject lives there too, so the subject’s actuality is the same as ours’

(Lewis 1996: 555).

rule of actuality and other world knowledge ascriptions
Rule of Actuality and Other World Knowledge Ascriptions
  • I didn’t watch the X-Factor results on Sunday. If I had watched them I would know which act left the show.
  • In the nearby possible world in which ES-B did watch the X-Factor results on Sunday, ES-B knows which act left the show.
  • The ascriber can ascribe knowledge to the subject that she (the ascriber) does not possess.
  • When the subject of knowledge ascriptions and the ascriber’s worlds are different, ‘it is the subject’s actuality, not the ascriber’s, that never can be properly ignored’ (Lewis 1996: 555).
rule of belief
Rule of Belief
  • ‘A possibility that the subject believes to obtain is not properly ignored, whether or not he is right to so believe’ (Lewis 1996: 555).
  • If Sally believes that Fred ate the last cookie in the cookie jar (when it was actually Tim), she cannot know that Tim ate the last cookie in the cookie jar.
rule of belief cont
Rule of Belief cont.
  • ‘Neither is one that he ought to believe to obtain – one that evidence and arguments justify him in believing – whether or not he does so believe’ (Lewis 1996: 555).
  • If Sally knows that Fred is allergic to cookies, and that Tim is a sucker for cookies (and regularly eats the last one), Tim’s having eaten the last cookie in the cookie jar is not a possibility which can be properly ignored when ascribing knowledge to Sally.
rule of resemblance
Rule of Resemblance
  • ‘Suppose one possibility saliently resembles another. Then if one of them may not be properly ignored, neither may the other’ (Lewis 1996: 556).

‘Unbeknownst to me, I am travelling in the land of the bogus barns; but my eye falls on one of the few real ones. I don’t know that I am seeing a barn, because I may not properly ignore the possibility that I am seeing yet another of the abundant bogus barns. This possibility saliently resembles actuality in respect of the abundance of bogus barns, and the scarcity of real ones, hereabouts’

(Lewis 1996: 557).





rules of method
Rules of Method
  • We can presuppose that a sample is representative.
  • We can presuppose that the best explanation of our evidence is the true explanation.

‘[W]e are entitled properly to ignore possible failures in these two standard methods of non-deductive inference’

(Lewis 1996: 558).

rule of conservatism
Rule of Conservatism
  • Generally ignored possibilities may be properly ignored (Lewis 1996: 559).
  • If certain possibilities are normally ignored by those around us, then (though defeasibly), we too may properly ignore such possibilities.
  • ‘We are permitted, defeasibly, to adopt the usual and mutually expected presuppositions of those around us’ (Lewis 1996: 559).
rule of attention
Rule of Attention
  • What is being properly ignored is a feature of conversational context. (Lewis 1996: 559).

‘[A] possibility not ignored at all is ipso facto not properly ignored. What is and what is not being ignored is a feature of the particular conversational context’

(Lewis 1996: 559).

  • In an epistemology seminar, we attend to the possibility that we are brains in vats, and hence this possibility cannot be properly ignored (because it isn’t being!) In the context of an epistemology seminar, we do not know that we have hands.
responding to scepticism
Responding to Scepticism

‘The pastime of epistemology does not plunge us forevermore into its special context. We can still do a lot of proper ignoring, a lot of knowing, and a lot of true ascribing of knowledge to ourselves and others, the rest of the time’

(Lewis 1996: 559).

hurrah for contextualism
Hurrah for Contextualism!

‘The obvious attraction of contextualism, besides (and closely related to) the resolution of sceptical arguments it purportedly provides, is that it seems to have the result that very many of the knowledge attributions and denials uttered by speakers of English are true’

(DeRose 1992: 924).

1 bizarre dialogues
1. Bizarre Dialogues

‘[C]onversations like the following seem to

be incoherent:

“A: Is that a zebra?

B: Yes, it is a zebra.

A: But can you rule out its being merely a cleverly painted mule?

B: No, I cannot.

A: So, you admit you didn't know it was a zebra?

B: No, I did know then that it was a zebra. But after your question, I no longer know”’

(Yourgrau 1983: 182–3).



response to 1
Response to 1.
  • Contextualism doesn’t license these dialogues.
  • Contextualism is a semantic thesis about knowledge claims, not about knowledge itself.
  • All that contextualism licenses is metalinguistic claims like:

‘I was previously such that an utterance of ‘B knows it is a zebra’ would have expressed a true proposition, but the different and more demanding proposition which such an utterance would now express would not be true’

(De Rose, 2000, section 6, cited in Rysview 2001).


Well, how should I answer the question? If there is no special reason to think they were painted mules then I certainly wouldn’t want to admit that I didn’t know they were zebras, but maybe I’m just being stubborn. Suppose I do admit it…



Do you know that?

Were there any zebras in the zoo on April 23rd?

Aha! The witness has contradicted his earlier claim. First he says that he knew; now he says he didn’t. Now which is it, Mr. DeRose?

Could you rule out the possibility that they were only cleverly painted mules?

I guess I didn’t know that they were zebras.

So, did you really know that they were zebras?


So, you knew that they were zebras?

No, I suppose not.

Is there any reason to think that they were painted mules, of all things?

Just answer the question!

I saw some there.

How do you know?

Dialogue from DeRose (1992: 925–6).

‘Surely something is amiss in this dialogue; my lawyer should object. I haven’t contradicted my earlier claim, as much as it looks as if I have. It would be as if the following had occurred. While standing in a bright yellow room, I said, “The room is yellow.” The lawyer then dragged me by the ear into a room in which all was grey and got me to say, “This room is grey,” and now he is jumping all over me: “First, he says, ‘This room is yellow,’ then he says, ‘This room is grey.’ Which is it?” The contextualist maintains that something very much like this has happened in my original dialogue with the lawyer’

(De Rose 1992: 926).

2 contextualism is off target
2. Contextualism is Off-Target
  • Contextualism misses its target (if its target is scepticism).
  • Contextualism has is that sceptical knowledge claims like ‘Moore doesn’t know he has hands’ are true only in contexts with high epistemic standards.
  • But the point scepticism pushes is that we do not satisfy ‘even our ordinary epistemic standards’ (Rysview 2011).

‘The debate about skepticism is […] not [a] debate in which the quality of our evidence is agreed to and the debate results from different views about what the standards for knowledge are. Instead, it is a debate about how good our evidence is. Understood that way, it is difficult to see the epistemological significance of decisions about which standards are associated with the word “knows” in any particular context. Contextualism is, from this perspective, skepticism neutral, in that it does not address this part of the issue’

(Feldman 2004: 32).

3 a disappointing response
3. A Disappointing Response
  • The contextualist response to scepticism: in ordinary contexts, claims like ‘Moore knows he has hands’ are true, in stricter contexts, claims like ‘Moore knows he has hands’ are false. So ‘in ordinary contexts the attributions we make using the word ‘knows’ are often correct, but in contexts in which skepticism is at issue […] the sceptics are right’ (Feldman 2001: 62).
3 a disappointing response cont
3. A Disappointing Response cont.

‘I routinely teach epistemology to undergraduates. One part of the course concerns arguments for skepticism. I've long thought that there were flaws in those arguments and that exposing them was an interesting, though not uncontroversial, project. I thought that going through the arguments helped to bring out features of the concept of knowledge and its application. Contextualists hold, however, that the arguments for skepticism are sound, or at least that their conclusions are true in the contexts in which they are discussed. So, if the contextualists are right, I've been wrong about those arguments (or at least their conclusions). That's disappointing’

(Feldman 2001: 62).

4 non sceptics and language competence
4. Non-Sceptics and Language Competence
  • If contextualism is right, competent speakers of English will agree with sceptical arguments – they should acknowledge that, in this context, Moore does not know that he has hands.
  • But:

‘There are intransigent skeptics who deny knowledge in virtually all contexts. There are those who are unmoved by skeptical considerations. […] On contextualist views, they don’t understand the language’

(Feldman 2001: 77).

  • Semantic Externalism
  • Seminars:
    • Do the reading!
    • Come with at least one question per topic.

Daukas, Nancy 2002: ‘Skepticism, Contextualism, and the Epistemic “Ordinary”’. The hilosophical Forum. Vol. 33, no. 1, pp. 63–79.

DeRose, Keith 1992: ‘Contextualism and Knowledge Attributions’. Philosophy and Phenomenological Research. Vol. 52, no. 4, pp.


De Rose, Keith 2000: ‘Now You Know It, Now You Don’t’. Proceedings of the Twentieth World Congree of Philosophy

(Philosophy Documentation Center). Vol. V, Epistemology, pp. 91 -106.

Dretske, Fred 1970: ‘Epistemic Operators’. The Journal of Philosophy. Vol. 67, No. 24, pp. 1007–1023.

Feldman, Richard 1999: ‘Contextualism and Skepticism’. Noûs. Vol. 13, pp. 91–114.

--------------------------- 2001: ‘Skeptical Problems, Contextualist Solutions’. Philosophical Studies. Vol. 103, No. 1, pp. 61–85.

-------------------------- 2004: ‘Comments on DeRose’s “Single Scoreboard Semantics’. Philosophical Studies. Vol. 119, No. 1/2.,

pp. 23–33.

Lewis, David 1996: ‘Elusive Knowledge’. Australasian Journal of Philosophy. Vol. 74, No. 4, pp. 549–567.

Moore, G. E. (1959) ‘Proof of an External World’, in his Philosophical Papers, London: Allen & Unwin; reprinted in T.

Baldwin (ed), G. E. Moore: Selected Writings (London: Routledge, 1993).

Pritchard, Duncan 2002: ‘Recent Work on Radical Skepticism’, American Philosophical Quarterly . Vol. 39, pp. 215–57.

Pryor, J. (2002), ‘The Skeptic and the Dogmatist’, Nous 34: 517–49.

Rysview, Patrick 2011: ‘Epistemic Contextualism’, Stanford Encyclopaedia of Philosophy, online at

Steup, Matthias 2005: ‘Epistemology’, Stanford Encyclopaedia of Philosophy, online at

Williams, Michael 2001: ‘Contextualism, Externalism and Epistemic Standards’. Philosophical Studies. Vol. 103, No. 1, pp.


Yourgrau, P. 1983: ‘Knowledge and Relevant Alternatives’. Synthese. Vol. 55, pp. 175–190.