PHIL2606: Knowledge, Reason and Action
Week 10: Ambiguity; Contextualism

    Denying validity: the ambiguity response

  1. Some people are attracted to the idea that the word 'know' is ambiguous between a weak sense and a strong sense. In the weak sense of 'know' I do know that I have hands, and I do know that I am not a BIV; in the strong sense of 'know' I do not know that I have hands, and I do not know that I am not a BIV.
  2. This weak sense of 'know' is sometimes called a fallibilist sense. I can know p in the fallibilist sense even if my justification for believing p is not conclusive, or does not entail p, or I have not eliminated all possibility of error. This strong sense of 'know' is sometimes called an infallibilist sense. I can know p in the infallibilist sense only if my justification for believing p is conclusive, or entails p, or I have eliminated all possibility of error.
  3. If 'know' is ambiguous in this way, then it might be helpful to introduce two new words, 'know-' and 'know+'. Let 'know-' have the same meaning as 'know' when used in its weak sense, and let 'know+' have the same meaning as 'know' when it is used in its strong sense. Then we can say this: I know- that I have hands, and I know- that I am not a BIV; but I do not know+ that I have hands, and I do not know+ that I am not a BIV.
  4. Proponents of ambiguity respond to the BIV argument as follows: either the argument is not valid (i.e. the conclusion does not follow from the premises), or it has a false premise, or the conclusion is perfectly acceptable after all.
  5. How does this work? If the BIV argument does not use 'know' in the same sense throughout the argument then it is not valid (it commits the fallacy of equivocation). For then it would be like the following argument:
    1. I went to a bank (a river bank)
    2. Therefore, I went to a bank (a money bank)
  6. So in order to be valid the argument must use 'know' in the same sense throughout. Then there are two possible ways to understand the argument:
    1. I do not know- that I am not a BIV (false)
    2. If I do not know- that I am not a BIV then I do not know- that I have hands
    3. Therefore, I do not know- that I have hands
    1. I do not know+ that I am not a BIV
    2. If I do not know+ that I am not a BIV then I do not know+ that I have hands
    3. Therefore, I do not know+ that I have hands (true)

    In the first case the argument has a false premise. In the second case the argument has a true conclusion that is perfectly acceptable.

    So if the BIV argument is valid, then either it has a false presmise or an acceptable conclusion.

  7. Problems for ambiguity

  8. First. Why is the BIV argument paradoxical? Proponents of ambiguity say something like this: we find the first premise acceptable because we understand 'know' in it in its strong sense; we find the conclusion unacceptable because we understand 'know' in it in its weak sense; we find the argument valid because we don't detect the difference in the sense of 'know'. But why don't we? In other cases it seems that we do.
  9. Second. Is there a weak (infallibilist) sense of 'know'? David Lewis rejects infallibilism as incoherent. “If you are a contented fallibilist, I implore you to be honest, be naïve, hear it afresh. ‘He knows, yet he has not eliminated all possibilities of error.’ Even if you’ve numbed your ears, doesn’t this overt, explicit fallibilism still sound wrong?”
  10. Third. Even if there is, do we even have know in the weak sense that we are not BIVs? Note that there is no difference in my evidence whether I am in a normal world or a BIV world, so do I have any evidence at all to support of my belief that I am not a BIV?
  11. Fourth. If 'know' is ambiguous in the way suggested, then there ought to be a reading of the following sentence on which it is not contradictory: "I know that I have hands but I do not know that I have hands." Is there?
  12. Fifth. If 'know' is ambiguous in the way suggested, then there ought to be a reading of the following sentence on which it is true: "I know that I have hands but I do not know that I am not a BIV." Let's accept that there is (which is not clear). There is still a concern. The explanation given is that we understand 'know' in a different sense in its two occurrences in this sentence. If that's right, then when we collapse it there ought to be something awkward about it: "I know that I have hands but not that I am not a BIV." (Compare: "At the bank I can get money and go fishing.") But is there any such awkwardness?
  13. Contextualism

  14. A currently very popular response to the BIV argument is to claim, not that the word 'know' is ambiguous, but that it is context sensitive, or at least that sentences of the form 'S knows that P' (i.e. knowledge ascriptions) are context sensitive. This is a slightly more sophisticated response than the ambiguity response.
  15. See:
  16. Context sensitivity

  17. When John uses the word 'I' he refers to himself; when Mary uses the word 'I' she refers to herself. So what the word 'I' refers to varies from use to use, or, as it is often said, from context (of use) to context (of use). So 'I' is context sensitive.

    But 'I' is not ambiguous - although John and Mary refer to different people when they use it, they use it with the very same meaning.

  18. Here are some other words standardly thought to be not ambiguous but context sensitive:
  19. Becaue the word 'I' is context sensitive, a sentence which contains the word 'I' is also context sensitive - which proposition it expresses varies from context to context. When John uses the sentence 'I am hungry' he expresses the proposition that John is hungry; when Mary uses the sentence 'I am hungry' she expresses the proposition that Mary is hungry.
  20. There seem to be sentences that are context sensitive even though none of their constituent expressions are context sensitive. Example: 'It is raining'. This might be used on one occasion to express the proposition that it is raining in Sydney, and on another occasion to express the proposition that it is raining in Canberra. So the sentence is context sensitive. But this does not seem to be due to any context sensitivity in 'it', 'is' or 'raining' - these are used on each occasion to express the same thing. (The 'it' here is the pleonastic 'it'.)

    So why is 'It is raining' context sensitive? Possibility: the proposition that it expresses contains constituents that are not represented at all in the sentence. Other possibility: the sentence contains a hidden indexical.

  21. Epistemic contextualism

  22. According to epistemic contextualism, the sentences that we use to ascribe propositional knowledge are context-sensitive.

    So it possible for speakers in different contexts to use the same sentence, 'Mary knows that she hands', and yet express different propositions. (And not because 'know' is ambiguous.)

  23. Moreover, and this is more to the point for us, it is possible for one speaker to assert, 'Mary knows that she hands', another speaker to assert, 'Mary does not know that she hands', and yet, despite how it might seem from the sentences that they use, there be no contradiction between them (the propositions they express are both true). This is because the proposition expressed by 'Mary knows that she hands' is different in their respective contexts.

    (In such a case we might say that the sentences are contradictory but the propositions expressed by them are not.)

  24. This is similar to what we might say in some other cases:
  25. According to contextualism, 'Mary knows that she hands' and the like are context-sensitive. Does that mean that 'know' itself is context-sensitive? Not necessarily - these sentences could be like 'It is raining'. So what do contextualists think about 'know'? They often don't make it clear. But in any case, what matters for them is that the whole sentence is context-sensitive (whether or not 'know' itself is).
  26. Motivation

  27. Why think that knowledge ascriptions are context-senstive? Here is an example used by Cohen to motivate the idea:

    Mary and John are at the LA airport contemplating a flight to NYC. They want to know whether the flight has a layover in Chicago. They overhear someone ask a passenger Smith if he knows whether the flight stops in Chicago. Smith looks at the itinerary he got from the travel agent and says yes, he knows. But Mary and John have a very important business contact they have to make at the Chicago airport. Mary says: ‘How reliable is that itinerary? It could contain a misprint, they could have changed the schedule at the last minute. Mary and John agree that Smith doesn’t really know that the plane will stop in Chicago, and decide to check with the airline agent.

  28. Sensitive to what?

  29. When an expression is context-sensitive there is generally some particular feature of a context of utterance to which it is sensitive. Examples:
  30. What feature of the context of utterance is a knowledge ascription sensitive to? Contextualists generally say that it is sensitive to the epistemic standard of the context.
  31. In ordinary contexts the epistemic standard is low. A speaker who asserts ‘Mary knows that she has hands’ in an ordinary context expresses the proposition that Mary knows to standard d that she hands, for some low d.

    In skeptical contexts (or epistemology classes) the epistemic standard is high. A speaker who asserts ‘Mary knows that she has hands’ in a skeptical context expresses the proposition that Mary knows to standard D that she hands, for some high D.

    These are different propositions. Moreover, they are not contradictory propositions - they can both be true (e.g. suppose Mary knows that she has hands to standard d+, where d < d+ < D).

  32. A couple of things to note:
  33. Responding to the BIV argument

  34. How does a contextualist respond to the BIV argument?:
    1. You do not know that you are not a BIV
    2. If you do not know that you are not a BIV then you do not know that you have hands
    3. Therefore, you do not know that you have hands

    As follows. The conclusion of the argument is the perfectly acceptable proposition that you do not know to a high standard that you have hands. This is because when the skeptic utters the sentence in the first premise, this raises the epistemic standard of the context, if need be (and by a mechanism to be discussed), until the sentence expresses a proposition that is true. This forces us into a high standard context. So we should not hesitate to accept the conclusion of the argument. Why do we hesitate? Because when evaluating the proposition expressed by the sentence in the conclusion we think of ourselves as being back in a low standard context - one in which the sentence expresses a false proposition.

  35. What about the second premise? Contextualists say that this is true in all contexts, no matter how high the epistemic standard. Why? Because no matter how high the epistemic standard is, if we know to that standard that we have hands then we also know to that standard that we are not BIVs; contrapositively, if we do not know to that standard that we are not BIVs, then we do not know to that standard that we have hands. (Compare: if the Nullarbor plain is flat then a glass table is flat; if a glass table is not flat then the Nullarbor plain is not flat - these are both true, no matter what the standard of flatness is.)

    In general, contextualists endorse Closure.

  36. This response to the BIV argument is similar to the response that we might naturally give to the following argument (they take the two to be analagous):
    1. A glass table is not flat
    2. If a glass table is not flat then the Nullarbor Plain is not flat
    3. Therefore, the Nullarbor Plain is not flat
  37. Some more details: DeRose

  38. There are at least two things we would like to be told more about:

    We will look at what Keith DeRose has to say about these things - his version of contextualism is one of the most thoroughly worked-out and influential.

  39. DeRose endorses Nozick’s account of knowing (at least as being on the right track):

    Necessarily: for all s and p: s knows p iff: (a) p is true, (b) s believes p, (c) if p were not true then s would not believe p, and (d) if p were true then s would believe p.

    I.e. Necessarily: for all s and p: s knows p iff: s tracks the truth of p.

  40. As we have seen, Nozick responds to the BIV argument by appealing to his account of knowing to argue that the second premise is false, and more generally that Closure is false. We can know that we have hands without knowing that we are not BIVs.
  41. DeRose doesn't like this, because it forces us to accept true abominable conjunctions: ‘I know that I have hands, but I do not know that I am not a (handless) BIV’.
  42. DeRose prefers a contextualist version of Nozick’s account:

    An utterance of ‘Mary knows that she has hands’ in a context C is true iff Mary tracks the truth that she hands as far from reality as the epistemic standard of C requires.

  43. This gives DeRose an account of what an epistemic standard is: it is how far from actuality a person must track the truth of a proposition in order to count as knowing that proposition. If the epistemic standard is low, then to know p one must track the truth of p only a small distance from actuality. If the epistemic standard is high, then to know p one must track the truth of p a large distance from actuality. How far from actuality someone tracks the truth of a proposition is a measure of the strength of her epistemic position with respect to that proposition.
  44. According to DeRose's account of knowing, the second premise of the BIV argument is true, no matter what context we are in (low or high epistemic standard). Why? Because no matter how far from actuality you track the truth that you have hands, you track the truth that you are not a BIV at least as far as that. Contrapositively, if you don't track the truth that you are not a BIV as far as d from reality, then you don't track the truth that you have hands that far either.
  45. More generally, DeRoses's account explains how the sentence we used to formulate Closure expresses a true proposition in every context:

    Necessarily: for all s, p and q: if s knows p and s knows that p entails q then s knows q.

  46. What is the mechanism by which the skeptic raises the epistemic standards? DeRose proposes the ‘Rule of Sensitivity’: When a speaker utters ‘S knows that P’ or ‘S does not know that P’, the standards for knowledge are raised (if need be) to such a level that to know that P one must track the truth that P at least as far as the closest worlds in which P is false. Compare: we are in a context in which the table is flat. But someone comes in and says ‘the table is not flat’; this raises the standards of flatness to make it true.
  47. DeRose thinks that this is better than Lewis’s ‘Rule of Accommodation’: when a speaker utters a sentence the epistemic standards are raised to whatever level is required to ensure that she expresses a proposition that is true. See Lewis, D. (1979), ‘Scorekeeping in a Language Game’, Journal of Philosophical Logic 8, pp. 339-59.

    DeRose objects to this rule:

  48. Problems for contextualism

  49. First. Why is the argument paradoxical? According to contextualists, we find the first premise plausible because we interpret its sentence as uttered in a high standard context; we find the conclusion objectionable because we interpret its sentence as uttered in a low standard context; we find the argument valid because we don't notice the shift in context. Why don't we? We seem to in the flatness argument.
  50. Second. Even if we grant that knowledge attributions are sensitive to the epistemic stadard of the context, is the epistemic standard in ordinary contexts any lower than in skeptical contexts. That is, are there really any low standard contexts?
  51. Third. Even if there are, do we even know to a low standard that we are not BIVs? Note that there is no difference in my evidence whether I am in a normal world or a BIV world, so do I have any evidence at all to support of my belief that I am not a BIV?
  52. Fourth. Suppose you, in an ordinary context, assert 'Mary knows that she has hands'. If someone were to ask me what you said, I would very naturally reply, 'He said that Mary knows that she has hands.' I would say this, even if I am in a skeptical context, and fully aware that I am. But if contextualism is right then I have mis-reported what you said. That seems like the wrong result. In general, we have to be very careful about using knowledge ascription sentences (just like we are with the word 'here').
  53. Fifth. Why would I ever take back what I said in an ordinary context if I move into a skeptical context (as I might well do)? Shouldn't I still endorse what I said (even though I can no longer say it, because of the different epistemic standard in my new context)?
  54. Sixth. If contextualism is right, then wouldn't we expect knowing to come in degrees? That's a problem, because it doesn't seem t0. (See Stanley (2004), ‘On the Linguistic Basis for Contextualism’, Philosophical Studies 119, pp. 119-46.)

Further reading

Exercise

No exercise this week - time to catch up/polish up.