Tuesday, March 02, 2010

What is fallibilism?

I've long been troubled by failing to understand what 'fallibilism' and 'infallibilism' are supposed to amount to. Here's an example of the sort of discussion I find puzzling.

Bohghossian and Peacocke write:
A priori justification is not infallible justification. Just as one may be justified in believing an ordinary empirical proposition that is empirically revealed on empirical grounds to be false, so one may be justified (non-conclusively) in believing an a priori proposition that is subsequently revealed on a priori grounds to be false.

I find this passage puzzling, for at least two reasons. First, Boghossian and Peacocke characterize a priori propositions for Boghossian and Peacocke as those which can be known a priori; so the idea of an a priori proposition that turns out to be false looks to me to be incoherent.

Second, it's not clear what the second sentence has to do with the first. The second sentence is about what may happen when you're justified in believing something -- that thing may turn out, either empirically or a priori, to be fase. The first sentence, however, isn't a claim about all justification; it's a claim about a priori justification. It can't be that a priori justification is fallible merely because it's possible to be justified in believing some a priori proposition that turns out false; if a priori justification is fallible, then there has to be a sense in which you can be wrong even if you're a priori justified. And that just isn't established or claimed in this passage. Is the idea supposed to be that any time you are justified in believing some a priori proposition, you're justified a priori? That would fill out the enthymeme, but it has the disadvantage to being totally implausible.

So I don't really know what Boghossian and Peacocke are up to here. Or, in general, what people who talk about a priori justification being fallible are up to.


  1. Jonathan Weinberg3/02/2010 05:27:00 PM

    I agree with you that there's an oddness in their defining apriority in terms of knowability, in this context, but if one just makes a friendly amendment from knowability to justifiability, doesn't that problem go away, at least?

    "if a priori justification is fallible, then there has to be a sense in which you can be wrong even if you’re a priori justified." I take it that this is exactly what is meant to be asserted in the passage you quote, even if, again, the author was insufficiently careful about how to say it. (I think it's clear from context that that that's what they mean; for example, it makes sense of what the two sentences have to do with each other!)

    Anyhow, suppose we stipulate that fallibilism about the a priori means exactly what you said here, something like, at the very least:

    (for some S)(for some p)[(S has a priori justification for p) & (~p)]

    (I think that often fallibilists about the a priori go further and at least endorse that this really has obtained with some frequency in the actual world, and that is part of how they argue for their fallibilism. I know Bealer makes just that sort of move.)
    On such a stipulation, if this is what these people have in mind, would there be something weird about it?

  2. Garret Merriam3/02/2010 05:36:00 PM

    Well, beliefs about the universality of Euclidean geometry seem to be a priori and false. Lacking a general theory of justification I'm not sure if I'd say they were justified, but I can imagine several theories of justification that would conclude they are. So unless you're saying that an adequate theory of justification can't allow for mistakes, then I'm not sure I see a problem here.

  3. Jonathan: yes, that's a view that I understand and know how to interpret; it states that a priori justification is not factive. But why should we believe that? I was taking B&P to be offering something like an argument that a priori justification had to be fallible; I don't see what it could be.

    Garret: why should we think that the claim that all space must be Euclidean is justified a priori? I'm not sure I see why we should think it's justified at all.

  4. Jonathan Weinberg3/04/2010 02:59:00 PM

    I think I see what your problem is -- you're coming at this from a very different angle than that of the authors and their intended audience. The history here is one in which the non-factivity of justification is taken as basically a given, not the sort of thing that needs any defense; but there was a legacy (from earlier versions of rationalism) of taking _a priori_ justification as needing to be incorrigible or infallible or something like that. So all that's going on, in the text you quoted, is the authors saying, "hey, there's really no reason to take a priori justification to be any more demanding than other forms of justification. All other forms of justification are fallible, so why not the a priori?" (I'm inclined to think they are right about all that, but that shouldn't be necessary for seeing what they are up to.) If one wants to debate the factivity of justification in general, I think maybe this literature on the fallibility of a priori justification is just not going to address the questions you're looking to address.

    Clarification: in your response to Garret, are you just rejecting that any _contemporary_ belief in the Euclidean structure of space is justified, or are you also rejecting that _past_ (in particular, pre-modern-physics) beliefs of that sort are justified? If it's just the former, then I think Garret's point still holds.

  5. Jonathan, well, ok. But that's not what they say. And it doesn't look obviously to be connected with what they say. That makes me suspicious that it's really what they mean.

    RE: the clarification: yes, I was talking about past beliefs. I don't see why we should think that such a belief about all possible space could be justified by the sort of evidence available to anyone in history.

  6. Jonathan Weinberg3/18/2010 07:31:00 AM

    "And it doesn’t look obviously to be connected with what they say." Why do you say that? It seems to me to fit _very_ well with both the quoted text and the rest of what they say, which is why it's such a good candidate for what they have in mind. It's on your (overly-)literal reading that what they say comes out as weird & under-argued. And this is all doubly so, in the context of the epistemological state-of-play as I indicated in my previous post.

    There's a certain style of philosophical exegesis where we hold every damn sentence someone writes up to a very tight scrutiny of all its quantifiers, etc. And I think it is often (though definitely not always) a poor mode of exegesis. What's important is that philosophers be extremely careful _in the places where they need to be careful_, and to be prepared to be more careful should such a need arise. These authors, very reasonably, did not feel a need to be especially careful in these glosses on their fallibilism. If reading them too tightly yields something incomprehensible, then the proper and charitable thing to do is relax the reading.

    Regarding the other matter, I reckon I hold with Garret on the question of old-timey beliefs in the Euclidean structure of space. It's only with the benefit of our more recent understandings about what sorts of claims can actually be known in what sorts of ways, that it looks preposterous -- not even justifiable -- to think that the structure of space or time could be discerned a priori. I mean, are you saying that Kant's arguments in the transcendental aesthetic don't even provide _justification_ for his claims? If so, then I think you've just got something weird in mind with the word "justification".

    I would also note that there's a weaker reading of "universality" in Garret's comments than the one I offered (and maybe it's the one he actually had in mind): the necessity of Euclid's Fifth Postulate, i.e., the impossibility of any non-Euclidean form of geometry. That, too, is something that was widely believed on an a priori basis, and (I think) with justification, but then ultimately falsified, also on an a priori basis.

  7. I think we could see the question of fallible a priori also in another way. If you consider justification with as background a theory of knowledge, and a way to characterize a theory of knowledge as compounded of many sources (perception, memory, etc) one of which is a priori source, at the same level of the others, I think you could say a priori is in a way ( but not in another sense) falllible. You must take into account the possibility of epistemic overdetermination (corroboration, disconfirmation etc). If you consider undermining defeaters (source sensible) and overriding defeaters (not sensible to a particular source), you could say a priori is infallible respect to the first, but not to the second. Here I consider a priori as a source of knowledge. Certainty would bring it to a higher degree than knowledge and would create a disparity among sources

  8. Jonathan Speke Laudly6/13/2010 09:23:00 AM

    Hi, Jonathan Speke Laudly here,
    False on a priori grounds?
    I define a bachelor as an unmarried man and assert that Joe is a bachelor because he is a man and unmarried--- until I find that he was in fact secretly married recently.
    Doesn't seem false on a priori grounds but empirical grounds. So, is it about changing the definition?
    Example: I exclude Bill from category of bachelor because he is gay. But subsequently I decide or observe that unmarried gay man is similar enough to unmarried straight man to be placed in the bachelor category. In other words, I change the definition --- thus Bill is a bachelor now on a priori grounds rather than empirical grounds? So, "Bill is not a bachelor" is now false on a priori grounds?
    But I changed the definition of bachelor because straight unmarried man is similar empirically to gay unmarried man--so if this means that I changed the definition on empirical grounds doesn't that make Bill now a bachelor on empirical grounds not on a priori grounds?
    Or did I change the definition simply by realizing that the category bachelor as already defined simply does include Bill and similar others; is it just a remedial inclusion then, a corrected oversight?
    What is so a priori, by definition, by tautology, by synonymy or by something or other, versus what is empirically so---seems not so clear.