A Puzzle

The philosopher Fred Dretske died the other day.  I had never read his work, but I had heard of him, of course, as he was one of the most prominent American analytic philosophers of the past half century.  Hearing of his death, I thought I would quickly look into the nature of his work, in very broad outline, and I came across a really cool paper titled “Epistemic Operators.”  In this paper Dretske argues briskly and convincingly that the following situation is perfectly coherent:

1) David knows that P.

2) David knows that if P, then Q.

3) David does not know that Q.

So here’s the puzzle: without looking up Dretske’s paper or any related materials, can you think of the kinds of example Dretske adduced in support of his remarkable thesis?

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7 Responses to A Puzzle

  1. Nates says:

    I’m stumped. Sounds like some sort of Gettier-style example? But I know almost as little Gettier as I know Dretske!

  2. Carolyn Richardson says:

    Hm, I don’t know, but I’ll make the unsurprising guess that the solution to the puzzle has to do with Dretske’s construal of the justification condition. But I can’t figure out what notion of justification could produce a situation such as poor David’s.

  3. juan says:

    Walter Edelberg, my thesis co-ordinator, taught an undergrad epistemology class last semester and told me about this and the examples Dretske gives. I’m not gonna ruin anybody’s fun tho.

  4. David says:

    Dretske was looking for counterexamples to what epistemologists–as I recently discovered–call a closure principle:

    (CP) If S knows that P, and S knows that P entails Q, then S knows that Q.

    Dretske first points out that some ‘operators’ do indeed follow (CP). For example, the operator ‘it is true that’ follows (CP): if it is true that P, and it is true that if P, then Q, then it is true that Q. When an operator like ‘it is true that’ is applied to P, the operator penetrates, as Dretske puts it, to all the logical implications of P. For this reason Dretske labels ‘it is true that’ a fully penetrating operator.

    Other operators are at the opposite end of the spectrum, as they do not penetrate at all to any of a proposition’s logical implications. For example, Dretske mentions the operator ‘it is strange that,’ as in (my example): ‘It is strange that (P) he wore yellow shorts to a funeral.’ (P) logically implies (Q) he wore clothes to a funeral, but it’s hardly strange that he wore clothes to a funeral! Also: It may be strange that Nates and Josh came to the party, without being strange either that Nates or Josh came to the party (perhaps they were supposed to be taking turns watching a baby or something). Dretske labels this class of operators nonpenetrating, and sometimes–tongue in cheek, I’m guessing–he refers to these operators as impotent.

    But Dretske’s real interest lies in the ‘epistemic operators,’ such as ‘knows that,’ ‘has a reason to believe that,’ ‘there is evidence to suggest that,’ ‘sees that,’ etc., and his thesis is that all epistemic operators are semi-penetrating–that is, they ‘penetrate’ to some but not all of a proposition’s logical implications. (I’m embarrassed to admit that the more I look at Dretske’s argument for semi-penetration, the less clear I am about the details and strength of that argument. Perhaps Juan can come to our rescue!)

    Let’s focus on the knowledge operator, since that’s Dretske’s main concern. Dretske wants to say that knowledge that P transmits to some of P’s logical implications, but not all. So, for example, if I know that Nates and Josh are coming to the party, then, necessarily, I know that Nates is coming to the party. But what about a case like this one:

    1) I know that the zoo animals I’m looking at are zebras.

    2) I know that if (P) the zoo animals I’m looking at are zebras, then, necessarily, (Q) I’m not looking at mules cleverly disguised by zoo administrators to look like zebras.

    So, here’s the question: do I know in this case that the zoo animals I’m looking at are not mules cleverly disguised by zoo administrators to look like zebras?

    Most everyone answers ‘yes.’ If I know that P, and I know that P –> Q, then I know that Q. (Of course, a certain kind of skeptic also says ‘yes,’ but then denies that I know Q and hence denies that I really know P. This sort of skeptic is Dretske’s stalking horse.) But Dretske disagrees with this bit of conventional wisdom. After all, if you asked me, ‘How do you know that these animals are not cleverly disguised mules???’ it is unlikely I would have much of a response. In fact I just hadn’t thought of that possibility. If you asked me, on the other hand, how I know that the animals I’m looking at are zebras, I could say a lot: they’re the right size and color, the sign says zebras, etc. Notice, however, that although this is good evidence in support of my belief that (P), it is not evidence in support of (Q): all the evidence I’m likely to adduce is consistent with the animals being cleverly disguised mules.

    So Carolyn was right, I think, that this ultimately comes down to issues concerning justification. Dretske seems to be arguing that one can have reasons for believing P that are not reasons for believing Q. In such cases, one cannot claim to know that Q even if one knows that P –>Q!

    If you follow Dretske this far, then, I think he wants to say, you have two options: you can become a full blown brain-in-a-vat skeptic, or you can say, instead, that knowledge that P does not always transmit to known logical implications of P.

    Pretty cool, right? Thoughts?

  5. Nates says:

    Interesting. I see that Dretske is drawing our attention to a problem with our concept of knowing, but it seems weird to put it the way he does. Let’s go with the Zebra example. We have:

    (P) I know that the zoo animals I’m looking at are zebras.
    (Q) I know I’m not looking at mules cleverly disguised by zoo administrators to look like zebras.

    According to Dretske, we can imagine cases where P is true, P > Q, but Q is false. And how might Q be problematic in these cases? David, standing in for Dretske, writes:

    “After all, if you asked me, ‘How do you know that these animals are not cleverly disguised mules???’ it is unlikely I would have much of a response. In fact I just hadn’t thought of that possibility. If you asked me, on the other hand, how I know that the animals I’m looking at are zebras, I could say a lot: they’re the right size and color, the sign says zebras, etc. Notice, however, that although this is good evidence in support of my belief that (P), it is not evidence in support of (Q): all the evidence I’m likely to adduce is consistent with the animals being cleverly disguised mules.”

    So, the strategy is to distinguish the epistemic reliability of P and Q, while still holding on to the inference P > Q. But I don’t find this convincing. After all, the fact that I haven’t thought of a possible doubt does not prevent this doubt from affecting the status of my knowledge claim. This is why we routinely take back claims to knowledge when an unnoticed doubt is pointed out to us. For example, I claim to know that an object is red, someone points out the weird lighting in the room, and I realize that I didn’t know the object was red after all.

    So, whatever makes Q problematic as a knowledge claim will also undermine P. For example, imagine I see used cans of black and white paint, and a trail of paint drops on the ground leading back to the animals. Surely this would be as much a reason to reject P as to reject Q! And the fact that I would be less likely to entertain this possibility when considering P than when thinking about Q seems irrelevant to the epistemic status of this doubt.

    If this is right, then we’re really just back to the skeptical position, Dretske’s stalking zebra, as it were. But this all seems too easy. Am I missing something?

  6. David says:

    Hey Nates,

    Here’s a much better explanation of Dretske’s position than the one I gave (I was limited by a desire to follow my own rules, and not look for clarification online). It’s from the Internet Encyclopedia of Philosophy entry on epistemic closure principles:

    Dretske’s account of knowledge is as follows: one’s true belief that p on the basis of reason R is knowledge that p if only if (i) one’s belief that p is based on R and (ii) R would not hold if p were false. Less formally, we may put this as follows: one knows a given claim to be true only if one has a reason to believe that it is true, and one would not have this reason to believe it if it were not true. (See Dretske 1971)….Let’s illustrate Dretske’s account with his famous zebra example (Dretske 1970). Suppose one is in front of the zebra display at the zoo. One believes that one is seeing zebras on the basis of perceptual evidence. Furthermore, in the closest possible worlds in which one is not seeing zebras (where the display is of camels or tigers), one would not have that perceptual evidence. Consequently, one knows that one is now seeing zebras, on the basis of the perceptual evidence one is having. Consider, however, the belief that one is not now seeing mules cleverly disguised by zoo staff to resemble zebras. Whatever one’s reason for believing this claim (say, that it is just very unlikely that the zoo would deceive people in that fashion), one would still have this reason even if the belief were false (and one was seeing mules cleverly disguised to look like zebras). Hence, one would not know that one is not now seeing mules cleverly disguised to resemble zebras.

    So it’s Dretske’s definition of knowledge which leads him to embrace the possibility that I can know P, P –> Q, but not know Q. The question, I suppose, is why we shouldn’t take this to be a decisive counterexample to Dretske’s definition of knowledge.

    I don’t have an answer to this, but I don’t think Dretske is vulnerable to counterexamples like your modified zebra case. In that case, what undermines my claim to know (P) that these animals are zebras is that under the circumstances there is a reason for thinking they are animals cleverly disguised to look like zebras–viz., the cans of black and white paint and the trail leading back to the exhibit. It is not the mere fact that I do not know that they are not animals cleverly disguised to look like zebras that undermines my claim to know (P).

    This relates to your remark that “we routinely take back claims to knowledge when an unnoticed doubt is pointed out to us.” Well, we sometimes take back claims to knowledge when unnoticed doubts are raised, but I don’t know if we do so ‘routinely.’ It depends on how we judge the merits of the doubts being raised. I don’t take back my claim to know that yesterday you promised me X after you point out that I might have been dreaming. I would probably take it back, however, if you revealed to me that your identical twin (who enjoys impersonating you) was in town.

  7. Nates says:

    OK, that helps. I’d like to know more about what motivates this conception of knowledge — seems pretty interesting.

    But right now I’m wondering: if P and Q really have different reasons that secure their truth — such that P can be true while Q is false (and vice versa) — then what justifies the inference P > Q?

    It seems obvious that if I know some animals are zebras, then I know that they’re not mules in disguise, but I wonder if our sense of the obviousness of this inference is based on a more traditional conception of knowledge.

    Does that make any sense?

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