Externalism and Defeat

In one of his comments on testimony and defeat, Jon K writes, “My view on defeaters is that if you think you have one, you do.” This is not an uncommon position, as Michael Bergmann shows in some of his papers on defeat. He endorses a “no defeater” clause on justification that says something to the effect that, if S believes that her belief that p is defeated, then S is not justified in believing that p, and he cites a number of externalist epistemologists saying about the same thing.

This is usually in response to counterexamples like those made famous by BonJour. In his clairvoyant examples, S’s belief that p is in fact reliably formed, but S has lots of other evidence against the belief that p, or against the belief that the belief that p was reliably formed. The typical externalist response is to say that the beleif is not justified because S has a defeater for it.

This strikes me as odd. To put it roughly, it seems like one is offering an externalist account of positive or supporting evidence for a beleif, but then “going internalist” about counterevidence or defeating evidence. Why should an externalist think that believing you have counterevidence makes it true that you have counterevidence? That is very close to endorsing the following principle: Jp => not-B(not-Jp). Which is equivalent to: B(not-Jp) => not-Jp. But what self-respecting externalist would say that?

If anyone is intersted, I am working on a paper about how externalists should think about defeat. I am working on the paper now, so any comments would be welcome.


Externalism and Defeat — 5 Comments

  1. John, send me the latest version and I’ll link to it in the sidebar (or tell me that the one I have is the latest version…)

    A couple of thoughts here. First, the worry about what an externalist should say about defeaters is a worry for you, but not for me (since I’m not an externalist). In fact, I’m probably too subjective about justification for my own good! I can’t speak for Michael, though, since I’m not sure enough about his view. Second, holding a subjective view of defeaters doesn’t commit one to the view that believing your not justified implies that you’re not. First, a defeater might only be a partial one, so that it merely decreases, rather than eliminates justification. Partial defeaters can’t be characterized in terms of believing you’re not justified. Second, even when the item in question is one that would undermine justification if it were the only piece of relevant information, there are also defeater defeaters to take into account. So if you have a subjective complete defeater, that still can’t be characterized in terms of believing your belief is unjustified.

  2. I thought the externalist reply to BonJour’s clairvoyance cases is in general OK since externalism is only the view that there are some external features over and above the internal states of the subject that determine whether or not the subject is justified, though S’s internal states may also be relevant, including whether he or she believes she is not justified. So, for instance, it seems like this response would be open to one who endorsed something like Alston’s “internalist externalism”.
    If one were a “pure” externalist, then I agree with you that the appeal to defeaters seems odd. For example, this kind of externalist shouldn’t think that one’s thinking about skeptical scenarios could defeat one’s (externalist) justification that, say, there is a hand. That would seem very bad and unfortunate for the externalist. However, in the case of clairvoyance, could the story be different? Could it be that the presence of defeaters messes with the reliability of the belief forming mechanism? So the (unwilling) clairvoyant has only a very fragile tendency to form beliefs that p when he clairvoyantly sees it in his mind that p? In the case of perceptually based beliefs about the existence of the external world, one might think the defeaters don’t as a matter of empirical fact disrupt the belief forming mechanism, because these faculties are just much less fragile.
    Anyway, your paper sounds interesting.

  3. Responding to Jon K, I know that YOU are not an externalist. I hope I did not imply that you are. Anyway, I agree with your qualifications, but I think the central problem remains.

    Responding to Alyssa, I think your comments are sound, and I agree that the difference between the unwilling clairvoyant and the normal perceiver is crucial. My target in the paper is those who think that defeat relations are necessary relations among propositional contents, whether these be logical relations or synthetic a priori relations. This is linked to internalism in that internalists have a motivation to think accordingly, since only such relations will be even plausibly accessible in the way the internalist needs them to be. On the other hand, externalists have no such motivation, and so endorsing such a thesis in response to BonJour-type counterexamples will seem ad hoc.

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