Polls Show that the Skeptic Is Right

I’ve spent a lot of energy dealing with this skeptical argument, that I’ve called “The Argument from Ignorance” (AI):

1. I don’t know that I’m not a BIV
2. If I don’t know that I’m not a BIV, then I don’t know that I have hands
So, C. I don’t know that I have hands.

I’ve always thought it a very promising object of study, because it’s valid, both its premises are intuitively very plausible, yet its conclusion is highly implausible (for some, it borders on the absurd). So you’re bound to find out something at least somewhat surprising, and perhaps even important, about knowledge in solving the puzzle this argument presents us with.

But in recent years, I’ve noticed something of a trend among philosophers – usually in conversation, but sometimes in print – to think this isn’t a very strong skeptical argument, perhaps not even worth working on. (Often they have some other argument skeptical argument they’re advocating as the “real” skeptical threat. Invariably, I think end up finding this “real” threat to be far less threatening.) Mostly, they’re worried about the argument’s first premise.

Now, I believe they have correctly fingered the argument’s weakest think. But I think it’s pretty strong for a weak link. (The reason I find the alternative threats less threatening is that I invariably find them to include some premise far less plausible than 1, above.)

Often, a key point in the discussion over the power of this argument is the matter of how intuitively plausible that first premise is. (One might also wonder whether our not being BIVs falls into some broader pattern of things that we intuitively seem not to know. I think premise 1 scores pretty highly here, but that’s a long story.)

I have a report from “the front” on the intuitive plausibility of 1. For three years now, I’ve started off my introductory Descartes-to-Kant survey course, a large course which mostly draws students with no previous philosophy classes, with the question of whether the students know that they’re not BIVs.

This is the very first thing I do in the whole semester. (I justify (rationalize?) the exercise by relating it to my lecture on Descartes’s First Meditation later in the opening meeting.) So I’m mostly receiving the verdicts of people “unspoiled by philosophy” – or at least by their contact with philosophy classes.

Here’s how I take my poll. The opening item on the lecture outline is: “A Philosophical Question or Two.” (“Or Two” because, depending on how I’m doing for time, I might also ask whether they think it’s possible that they are BIVs, which can later facilitate discussion of the second great argument by skeptical hypothesis, like unto the first, the “Argument from Possibility.”) I write these options on the board: “I know that I’m not a BIV” and “I don’t know that I’m not a BIV.” I prepare by explaining the BIV hypothesis, but refraining from using terms of epistemic appraisal in my description of the hypothesis. (So, for instance, I’m very careful not to say anything even remotely like, “So, if you are such a BIV, you can’t tell that you are,” since I take “can’t tell” to be a question-begging negative assessment, or at least to be question-beggingly close to being a negative assessment, of any belief one might have to the effect that one is not a BIV.) I then tell them that I’m going to take a show of hands on the question of whether each student thinks she does, or does not, know that she’s not a BIV. The first time I did this, I noticed a lot of glancing about by the students as I waited for the first show of hands. This made me worry that many were being influenced by how others voted. So the last two times I did this, I explained to them that I would wait quietly a few seconds to let everyone make a firm decision in their own minds as to what they thought, so they wouldn’t be influenced by how others were voting when I did ask for a show of hands.

The results were extremely strong. The first time I did it, I got these results (as reported in note 15 of my paper “Sosa, Safety, Sensitivity, and Skeptical Hypotheses,” forthcoming in SOSA AND HIS CRITICS, but on-line in draft form here [word format] and here [pdf format]):

I recently took a poll in a class of over 70 introductory philosophy students….My question was whether or not each student, in her or his own opinion, knew that she or he was not a BIV. A clear majority — about 2/3 of the class, it seemed, though I didn’t count — of the hands went up. So most of these students agreed with the skeptic on this issue. When I asked who thought they did know they weren’t BIVs, only three hands went up.

The last two times, the results were even stronger. I suspect it’s really about as strong as you can hope for from undergraduate classes on just about any question – including whether killing babies for the fun of it is morally wrong. Well over 80% voted that they didn’t know, and in each case, less than 5 (in classes of about 100 students, which is what this course has drawn for the last two years, at least for its opening meeting during Yale’s “shopping period” – before I frighten some off with such questions!) voted that they did know. (So there were still some abstainers. It’s possible that there were fewer abstainers the last two times because of my instructions to firmly make up their own minds before I took the show of hands.)

Perhaps others have obtained different results. I’d then be interested in some details about how the opinions were collected. One very important feature of how I do things is that I do not present any skeptical arguments until after I’ve taken the vote. Explaining and then asking the question of whether they know they’re not BIVs is really the first thing done in the course. If students are presented with the question in a format where it’s clear that a negative verdict on whether they know they’re not BIVs forms an important part of an argument designed to show that they don’t even know they have hands, many might decide that they do know that they’re not BIVs in order to escape the threat the argument poses. (Of course, some may worry about such skeptical threats on their own, without having to be presented with the argument.)

All of this can lead one to think that AI really is a remarkable argument. Any argument whose weakest link is that intuitively powerful and yet has such an implausible conclusion is something of a wonder.


Polls Show that the Skeptic Is Right — 18 Comments

  1. I don’t know how the attempts not to influence the students could be very effective. Surely they’ve all had the scenario explained to them before, if not exhibited convincingly in movies (Matrix, Total Recall, and lots of others.) This must be a case where the general culture has fully absorbed the bit of philosophy, so that no one can really escape it.

    Perhaps the outcome is also biased by the fact that it’s a philosophy class, and they “know” that this sort of case is central to some concerns of philosophers.

  2. I agree, I think, with Steven. In fact, I’ve done the question on non-philosophy youth: when I was coaching baseball teams that my son was on. They thought the question weird and stupid; the universally claimed it was obvious they weren’t brains in vats. “I’m batting .450; brains in vats can’t do that!” Only my son hesitated, but then went along with his teammates (I did this from age 12 through 16); but he’s been corrupted by philosophy from his earliest cognitive experiences…

  3. I’m certainly aware of the limitations of such a poll. (The title of my post was a joke, of course.)

    Still, I was shocked by the strength of the results. They weren’t at all what I expected — or what I was led to believe they’d be by other philosophers who reported experiences with students that sounded quite similar to Jon’s experiences with his son’s teams. I’m hoping that presenting, in some detail, how I conducted my poll (though the exact way I described the BIV hypothesis, which I have not gone into, is probably quite important) might be of some help in locating the reason why I’ve been getting such different results.

  4. I agree with the above comments but I may have something to add. I was wondering if I could suggest something like a “control” for this experiment. It seems to me that introductory phil students are pretty skeptical in general. Thus, it might not be anything special about the BIV hypothesis that’s responsible for the results you’re getting. How about also asking them some other questions, such as “Do you know that this is a chair?” or “Do you know that the sun will rise tomorrow?” or “Do you know [some proposition that has been reported to them]?” Asking various questions such as these might help one get a good idea of just wherein there skepticism lies.

    Specifically, it might also be a good idea to ask them “Do you know you have hands?” as a way of gaining support (via the same route you have attempted for your claim about premise 1) that the conclusion is (or is not) “intuitively implausible”.

    Of course, the type of experiment I’m envisaging might not be feasible in the classroom due to the necessity of asking the questions of different groups (so as not to influence the answer a student gives to one question by having previously asked that student one of the other questions).

  5. I suspect that people are more likely to associate knowledge with certainty when you ask them a question about a negative. When you ask “Do you know that you’re not a BIV?”, many will focus on the stated possibility of being a BIV and think “Well, I suppose it’s possible that I’m a BIV.” They may think that this is what the question is after, and conclude that they don’t know that they’re not a BIV. If you asked people whether they knew a positive, like whether they knew they had hands, they would not focus as much on the (implicit) possibility of not having hands so they’d be less likely to think “well, I suppose it’s possible that I don’t have hands.” Even if they did think this, they would be less confident that this was what the question was really asking for, so they’d be less likely to say that they didn’t know.

    I suggest that, after your students have given their answer, you ask them to raise their hand if they had a thought like “I suppose it’s possible that I’m a BIV” and then to keep their hand up if this thought was important in reaching their conclusion. You might also have your students write down all their answers & hand them in, in addition to raising their hands, so that you can get an exact count after class (and in order to be more confident that they’re giving their personal answers).

  6. Jonathan Weinberg posted a note on my experimental philosophy blog about this discussion. Very fascinating. I have two quick comments: On the one hand, it is methodologically problematic to rely on hand raising as a means of getting data about subjects’ intuitions as the overt publicity of a showing of hands creates peer pressure, etc. So, there are reasons to question the results of these results of informal surveys such as the ones the Keith discusses. On the other hand, if we assume for the sake of argument that additional studies (free of some of the methodological problems of the original ones) reveal that the majority of non-specialists do judge that they do not know that they are not a BIV, how should this spsort of data affect the philosophical debate? Minimally, it would help place the argumentative burden of proof on the philosophers who argue contrary to folk intuitions. But beyond that, what is this kind of empirical data good for–philosophical speaking? Obviously, I am biased, but I am curious to see what others have to say. BTW, I really like your site–I am sorry I was slow putting a link to it on my own blog.

  7. I can report similar experiences to Keith on this score. Interestingly, I’ve found that if you *explicitly* give students three options (K(BIV), not: K(BIV), and unsure either way), then the majority opt for ‘unsure’, whilst if you stick with just the first two they tend to go for the second. I’d imagine that this is because there is less of a commitment to saying that you don’t know something than saying that you do, so if you’re unsure opting for the ‘don’t know’ option is preferable to saying you do know. I recently noted the fact that students tend to have the intuition that they don’t know that they aren’t BIVs (or are at least unsure whether they know) in a paper I gave at the ‘Knowledge and Scepticism’ conference in Moscow, USA, last April. Kent Bach, who was in the audience, argued that in fact the empirical data was entirely different, in that in his experience the majority of students felt that they did know this kind of thing. So there isn’t much in the way of consensus here.

  8. I too am glad to see more philosophers interested in the intuitions of folk who have not yet been influenced by philosophical arguments, intuitions often cited by philosophers as support for the plausibility of their premises. Though there’s a lot of work to be done to figure out the role of such intuitions in philosophical debates (and how best to research such intuitions empirically), at a minimum they seem relevant in determining the degree to which philosophical concepts (e.g. knowledge, free action, etc.) map onto concepts as used by non-philosophers. And that is relevant to the degree that philosophers want their concepts to accord with and account for ordinary usage, rather than developing a technical concept.

    If interested in these issues, the address for the experimental philosophy website created by Thomas (and mentioned in previous note in this thread) is: http://experimentalphilosophy.typepad.com/
    There (in the thread “Testing folk on free will and determinism), I discuss some surveys we ran on folk intuitions about free will and moral responsibility (subjects were students who had not yet taken any philosophy).

    Nichols, Stich, and Weinberg have a paper “Metaskepticism” that reports lots of relevant surveys, including if I remember correctly, one that shows students with more philosophy classes are more likely to think they just believe (rather than know) they are not BIVs. Of course, one problem with surveys of students who have taken philosophy is that their responses will likely reflect the views of their teachers (even if their teachers have tried to present both sides fairly).

  9. It’s very interesting to see the wide divergence of results that people get when presenting non-philosophers with such cases. I do this quite often, and people almost always say they know that they’re not a BIV, usually without hesitation. They find it very strange that I would ask such a thing. So my experience is like that of Jon’s with his son’s baseball teammates.

    People reading this thread might be interested to know that I recently posted the details of how I interview people regarding a variation of Dretske’s zebra/mule case (http://www.brown.edu/Departments/Philosophy/Blog/Archives/004544.html).

  10. I’m going to engage in some extremely irresponsible armchair speculation, in the spirit of a hypothesis that might later be tested by experiments.

    That is–maybe it makes a difference that the people Keith surveyed were sitting in a classroom, while the people Jon surveyed were actively playing baseball. That might provide support for Hume’s idea that these concerns seem less relevant when you’re playing backgammon.

  11. A few responses, most of them very quick, to some of the parts of some of the above comments:

    Re 6: I’ve never asked students whether they were thinking about possibility as they voted on whether they knew. But at least once I did also ask – this after the question about whether they knew – whether they thought it was possible that they were BIVs. (On the board: “It’s possible that I’m a BIV” and “It’s not possible that I’m a BIV.”) The results, I recall, were roughly the same as with “I know/don’t know”, with a clear majority voting that it is possible, only a very few voting that it is not, and a several abstentions. The question about possibility came after the question about knowledge, and, as I think is well-known, the results therefore can’t be counted on to be the same as they would have been if the possibility question were asked first, since earlier answers tend to influence how people answer later questions.

    Re 7: Peer pressure certainly is a concern, and my attempt to avoid it (as described in the post) certainly isn’t a sure success. As for the value of such information about “intuitions,” I can at least say why *I’m* interested: See the reply to comment 9.

    Re 8: As I’ve said, like Duncan, I’ve been told by various philosophers that most of their students think they do know they’re not BIVs. That’s why I was so surprised with the results of my survey. What would help is if those who report such findings, like Kent or John Turri (comment 10) would also describe the circumstances under which they obtained this info.
    It’s pretty plausible that I would get more people not saying whether they knew or not if I, like Duncan, explicitly gave a “unsure” option. I don’t know whether it’s a good idea to include that option. Probably, it’s worth trying both ways. I myself don’t do it for the philosopher’s reason that “Yes” / “No” / “Unsure” doesn’t divide logical space nicely. [I remember encountering a table of positions on freedom and determinism somewhere – I *think* in Galen Strawson’s book – which had columns for such statement as “Determinism is true”, “We sometimes act freely”, “Determinism is compatible with free action”, or something like that, etc., with three options for each statement: “Yes”, “No”, or “Don’t Know” (or something like that), with the various positions characterized by how they answered the various questions. And I remember thinking to myself that my position, at least as defined by the chart, assuming that “Yes” or “No” indicated that I *did* know that “yes” or “no”, was one that wasn’t represented: one according to which every question received the answer of “Don’t know.” I have fairly stable beliefs about some such issues, but *KNOW* them?]
    The substantial number of “unsure”s that Duncan received seems like bad intuitive news for the thesis that knowledge is a transparent state!

    Re 9: I read the NS&W paper, but it was quite a while ago – I think before it came out – and I don’t remember it all that well. (Not that it wasn’t memorable; in fact, I recall that it *was* memorable. However, that apparently didn’t cause me to remember it very well!) Anyway, my recollection of my reactions to the results may reveal something about why I’m interested in people’s intuitions about such epistemic matters. What I mostly remember is thinking that, while the differences between various groups seemed surprisingly significant, on at least most of the questions that have mattered to my work, I was actually reassured, rather than worried, by the results. For even among the groups where fewer people agreed with the evaluations I use as something of starting points for arguments I’m interested in, still, enough of them agreed with me to make me happy. Instead of, “Uh-oh, only 65% of respondants in Group A agree with me,” I thought things along the line of, “Wow, even in group A, 65% will agree with that premise!”
    So, that probably reflects my unrefined attitude toward intuitions in philosophy. I tend to think of “intuitions” fairly broadly, which encourages such thoughts as this: Every argument has to start with *some* ultimate premises – some claims that one doesn’t argue for. What can one hope for from such starting points? Intuitive plausibility – that they seem true – sure sounds like a good feature for those starting points. Certainly better for one’s starting claims to seem true than for them to seem false!
    (Of course, things are messier than those comments indicate. Often, you have premises that are such that you have *something* to say in their favor, but they are still in some important sense “starting points”, because you don’t accept them just because of the considerations you’re able to cite in their favor, but also partly because of their own “intuitive plausibility.”)
    But seems true to whom? Well, at the risk of sounding self-centered, I’ll reveal that what’s really essential is that my starting points seem true to me. In fact, even if most others disagree, I would be interested in working out the best picture that I can from “personal” starting points – and would see some point in presenting the results of such work to others. As I recall, Peter van Inwagen’s super book, MATERIAL BEINGS, starts off by listing a bunch – 10, if I’m remembering right – theses that comprise his starting points, at least for the purposes of that book, many of which are very controversial, and, as PvI realized, would remain extremely controversial even after his brief remarks about them, which are partly designed to motivate them. I disagreed with more than one, but found the book extremely valuable. What’s important to a position is not just how intuitively plausible its starting points are, but how well the final position hangs together, how well objections can be handled, etc.
    But I would prefer it if my starting points were also acceptable to many — or even better, most — others. Especially relevant to me is how my students react, since they are the people I teach. Even if they don’t agree with my starting points, it may be worth presenting to them my positions – in this spirit: “I know most of you won’t agree with my starting points, but the whole picture might still be of interest to you, and might even be appealing.” But it’s worth knowing how they react to your starting points to know how to effectively present the material. And it’s good to know how many of my fellow philosophers agree with me, since they’re the main audience of most of my writings. But I’m also interested in knowing to what extent philosopher’s opinions are shaped by current philosophical fashion – because then I’d feel a bit better about going against the professional grain. That beginning students believe something is some evidence that professional opinion in the other direction might be a result of current philosophical fashion.

    Re 11: Matt’s speculation strikes me as very plausible – and if it’s irresponsible, it’s no more so than speculation I’ve engaged in here. However, this doesn’t explain why I get such different results from those who report that their students think otherwise, since that probably came out in classrooms as well. Again, it would help to know such things as: Do these teachers first present the whole skeptical argument before asking the question? Do they make it known what they think before they ask? Etc. What I liked about my way of asking is that it was the very first thing I did for the whole semester, so students probably didn’t know my own position. And even if I was somehow subconsciously letting on what my position is, my own contextualist position on the issue is too messy to give much guidance on how to answer a yes-or-no question.
    Jon’s subjects were playing baseball, rather than sitting in a philosophy class, and it would be quite surprising, at least to me, if that *weren’t* relevant to the outcomes of our surveys. But, still, I’d want to know more about how Jon elicited his opinions – and exactly which opinions were advanced. What Jon explicitly reports is not that his young, baseball-playing subjects said they did know that they weren’t BIVs, but rather this: “They thought the question weird and stupid; the[y] universally claimed it was obvious they weren’t brains in vats.” But I’ve generally found people much quicker to say such things as that the question is weird or stupid, or that it’s crazy, bizarre, or even absurd to suppose that one is a BIV, or that it’s obvious that one isn’t a BIV, than to say that they know that they’re not BIVs.

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  13. UPDATE, 1/10/05: Just repeated the experiment on a new batch of 103 students. The results:
    -5 said that they did know they were not BIVs
    -98 said that they didn’t know that they were not BIVs

  14. I did a similar experiment today on around 80 Intro students, and the results were more or less 1/3 said they don’t know, 1/3 said that did, and 1/3 didn’t answer (maybe a bit more for don’t know). I did catch myself saying things like “if you are a BIV, then you don’t know that you are,” but isn’t that uncontroversially true? It would of course be problematic to say that the BIV hypothesis is such that you cannot know whether it is true, but I didn’t say that. In any case, if anything my presentation of the hypothesis should have had the effect of having more people say that they didn’t know, if anything. I’m pretty sure I’m letting them know what I think about the issue, but I sure cannot figure out how!

  15. As an anti-skeptic, I feel the poll would be more fair to my side, if the question was something more like:

    “Do you think you could reasonably hold that it’s relatively less plausible (or probable or likely) that you are a BIV, than that you aren’t?”

  16. New report from the front, 1/13/09: After a few years off, I’m teaching the class again, and we just had our first meeting. Same procedure. 83 students in the room, by my count. “I know that I’m not a BIV” got 4 votes. Everyone else (there may have been an abstainer here or there, but I didn’t notice anyone) joined the sea of raised hands voting for “I don’t know that I’m not a BIV.”

  17. Tried it again at the opening class this semester (on Tuesday, 1/12/10). “I know” did unusually well compared with previous surveys, but still quite poorly:

    “I know that I’m not a BIV”: 6
    “I don’t know that I’m not a BIV”: 42

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