Friday, October 23, 2009

Epistemic Modals and Contextualism

Here's an insanely simple argument for contextualism about knowledge. I think it's sound, although I'm not sure I'd expect many people to be persuaded by it. I'd be interested in hearing about how readers might think it best to resist it.

Here's premise one. Epistemic modals are intimately connected to knowledge in something like the following way: it might be that p iff the relevant base of knowledge doesn't entail that not-p. This is pretty much standard, I think, although of course people argue about just which knowledge base is the relevant one. This much looks like common ground, for instance, in the debate between contextualists and relativists about epistemic modals. What's at issue there is how the relevant knowledge base gets fixed -- whose knowledge counts. If you need an argument for this connection, just reflect on the absurdity of "it might be that p, but I know that not-p" and "I don't know that p, but it must be that p". (I'm assuming the duality of might and must.)

Here's premise two. In many situations, both of the following obtain: (a) were someone to say "I know that p", that utterance would be accommodated and accepted as true; (b) were someone to say "it might be that not-p", that utterance would be accommodated and accepted as true. For example, in my current situation, I could truly assert "I know that Derek will respond to Paul (because that's what the workshop schedule indicates)". Alternatively, I could truly assert "Derek might not respond to Paul (because it's possible that he'll get sick during the lunch break and have to go home)." (Of course, I can't go both ways; in no context can I say both things; the point is that in some contexts I could say either.)

These two premises, all by themselves, put the invariantist in hot water. Take one of the situations described in premise two, and suppose invariantism is true. In that situation, by premise two, "S knows that p" expresses a truth in some context; therefore, by invariantism, it expresses a truth in all contexts. But, by premise one, "S knows that p" is inconsistent with "it might be that not-p". So this modal claim must be false in all contexts—against the stipulation of premise two.

The obvious solution, from my point of view, is contextualism about 'knows'. Then we can maintain the connection between 'knows' and 'might' in all contexts, and have each sentence true in some context. I don't see any option nearly so appealing for the invariantist. But this argument is so simple that it can't be decisive. So what should the invariantist say?


  1. Interesting argument, Jonathan.

    I think the invariantist about knowledge should deny premise one, and offer a pragmatic account of any infelicity resulting from asserting the relevant conjunctions. Rysiew and Dougherty have done some interesting relevant work on concessive knowledge attributions (PPR, Jan. 2009).

  2. The SSI invariantist (or at least my version of SSI invariantism) can accommodate all the data I think. I think it matters a lot to whether you know that p whether you can rule out all of the alternatives to p that are salient to you. And you get to sort of decide what's salient to you. (To some extent - if there's a train coming towards you and you're on the tracks, it's salient whatever you decide. But we have a lot of latitude.) If you make Derek's health after lunch salient, and you can't rule out possibilities where he's sick and can't respond, then you don't know.

  3. agreed with brian. perhaps a different way of making is point is that (1) and (2) seem equally tenable (although neither strikes me as especially plausible).

    (1) both Kp and might(~p) are true/assertable in light of the information of c
    (2) both Kp and might(~p) are true/assertable in light of the information of S

    ...if "information" is understood to exclude which alternatives are salient with respect to S (or c).

  4. John: yeah, I had a vague memory of that Rysiew and Dougherty piece; thanks for the citation -- I'll have a close look. If the invariantist has to give up the connection between knowledge and epistemic modals, that, I think, is a pretty significant result of this argument.

    Brian: good point, the argument as given doesn't favor contextualism over the relevant kind of IRI. That's slightly embarrassing, since I often take a pretty critical view of people who fail to make that distinction; I definitely should have been more careful.

    However, it looks to me like a third-person version of the argument should be about as strong. Sometimes, we use epistemic modals to talk about somebody else's evidential situation; it looks to me like we have the same flexibility to choose between 'S knows p' and 'it might be that not-p' (where that might is clearly meant to signal S's epistemic situation -- we can force this interpretation by talking about cases where we know p). For example, suppose we're watching The Princess Bride for the hundredth time. Westley has heard an announcement that Buttercup is going to marry Humperdink, and truly believes, on this basis, that Buttercup is engaged to marry Humperdink. It seems to me that we could felicitously describe Westley's situation in either of these ways: (a) "Westley came to confront Buttercup because he knew she was engaged to marry Humperdink"; (b) "Westley had good reason to believe that Buttercup was engaged to marry Humperdink. But of course, testimony is sometimes unreliable. It might've been that it was just a rumor -- still, it was likely enough to make the trip worthwhile. And of course he ended up being right." This kind of data, it seems to me, is just as strong as the data in the post. And I don't see how the IRI view explains it.

    Nate: I'm confused. Don't your (1) and (2) just flatly contradict my premise one? I'm not sure I see how this connects to Brian's point.

  5. Jonathan: Yes, though that premise isn't "standard." Yalcin thinks epistemic modals are sensitive to the issues/questions that are salient in the inquiry. Thony and Kai think they signal something about the character of the available evidence. Although I don't know that anyone explicitly endorses this, you might say they're sensitive to salient alternatives, in the same way knowledge is (because, e.g., you think it's a datum that might(p) iff ~K~p, which doesn't seem crazy to me). (I thought this was what Brian was getting at, but I probably misunderstood.)

  6. (Of course, by SSI I meant IRI! I'm often grumpy at people who use 'SSI' to mean IRI, so that's somewhat embarrassing on my part.)

    I don't think (b) in The Princess Bride story is inconsistent with saying that Westley knew that Buttercup was engaged. I think a large part of the context dependence of 'might' is that there's some flexibility in which epistemic relation the salient person must stand in. The natural way (for someone who denies E=K) to read (b) is as saying not that Westley's *knowledge* was consistent with Buttercup not being engaged, but as saying that his *evidence* was consistent with Buttercup not being engaged.

    I'm not super confident about that last paragraph because I don't really have a good grip on how tense-shifted epistemic modals work though. I find them a little mystifying actually...

  7. Brian, do you then want to say that "Westley knew that Buttercup was engaged, but she might not have been"? That doesn't seem to me to be possible, if 'might' gets an epistemic reading.

    (And of course, 'your version of SSI' is IRI. So there's a happy reading of your first language. :P )