Many months ago I posted an entry on my blog, the thesis of which is that Nozick begs the question against the skeptic in his well-known defense of the tracking account of knowledge. You rebutted my post, and I in turn responded to you. This resulted in a series of exchanges. Several months ago I deleted the post because it was difficult for the reader to follow, and I was too lazy to edit it. But I have not stopped thinking about the exchange that we had, and I recall enough of it to allow for an accurate reproduction. The intuitions on which I was relying during our exchange are still very strong, and so I feel that you might want to hear my response to your thoughtful comments after this period of reflection. Furthermore, I have recently come across an essay that expresses many of the points I tried to express. This will assist the clarification of my position.
My argument was simple: Nozick seems to assume throughout his argument, especially with his comments such as "If I were not in Jerusalem (or wherever) I would be in the U.S" that he is actually not a BIV. I argued that he does not argue for this assumption. Until he does argue for his assumption, then he will have no response to the skeptic who is himself giving a well-reasoned argument that nobody can show that he is not a BIV.
You responded in a now familiar manner: Nozick is arguing for an externalist theory, not an internalist one. Therefore, he does not need to give any argument to show that he is not a BIV: that is an internalist obligation, not an externalist one. Nozick merely has to show that it is POSSIBLE that we have knowledge. He does that, because, assuming that we are not BIV's, THEN we have knowledge.
I responded in the following way: Nozick has no grounds for assuming that we are not BIV's, and that this assumption stacks the deck against the skeptic, since the total absence of evidence for this assumption is what the skeptic's argument depends on.
You responded that Nozick has the right to make this assumption, because a person can assume anything that he wants FOR THE SAKE OF ARGUMENT.
This is as much of the exchange I recall. So now let me give you my latest thoughts.
My first objection to your first response: There are actually two assumptions that must be made. The first assumption, like we have already seen, is that we are not BIV's. But a second assumption must also be made: that Nozick's analysis of knowledge is correct. I do not think that this assumption is justified because I think that Nozick's analysis, like all externalist analyses, are VERY inaccurate. I think that knowledge is very much related to epistemic norms such as the right to be certain, etc, and I think that it can only be all right to be certain if you can justify your certainty with an argument. But since any disagreements on this issue end up being fruitless intuition battles most of the time, I will say no more about it. I would just like to make the point that there is a second assumption here, not just one.
My second objection: I do not think that your characterization of the skeptic's position is the best one. You characterized the skeptical thesis as the claim that knowledge is impossible. I would like to offer a different characterization of the skeptic's position that I think better captures the point he is trying to make. Here I borrow from the essay I mentioned above, "Skepticism and Naturalized Epistemology" by David Shatz. He claims that there is the following sort of skepticism that most externalists unjustifably ignore:
Dialectical skepticism: There is no dialectically effective argument for our first-level belief commonsense beliefs or our second-level commonsense beliefs.
Clearly Nozick is helpless against this form of skepticism, and it is this form that I was assuming in my critique. I think that Nozick realizes this, though since I recall (it has been months since I read the essay) that he concedes that this form of skepticism cannot be refuted.
Now I would like to borrow more from Shatz; these thoughts should show that Nozick's point is, if any sort of victory at all, a very small one.
Consider a man who thinks that the BIV scenario is true. He uses this hypothesis to account for the irritations of his sensory receptors in the same way that we use the hypothesis of commonsense realism to account for ours. When this fellow has table-like experiences, he hypothesizes that his vat caretakers are now stimulating his nervous system to have table-like experiences. Surely we would want to object that this fellow has no warrant for his hypothesis. But he can respond to our challenge in the same cowardly way that externalists respond to the skeptic: "That belief MAY be reliable. If I really am a BIV, then (to parody Nozick's account of knowledge) I know that I am now being stimulated by the caretakers to have these table-like experiences provided that, if these caretakers WEREN'T stimulating me, I WOULDN'T have such experiences." (Shatz 130). Now clearly this man has no argument that his belief is reliable in this way, just as the externalist has no argument whatsoever for the claim that his beliefs ARE reliable. I think that this thought experiment shows that this assumption that we are not BIV's, whether for the sake of argument or what have you, is just laughably without warrant in the same way that the fellow's assumption that he is a BIV is without warrant. This creates a serious problem for any externalist who thinks that he has even come close to refuting skepticism of the (most) important sort I have described.
I hope that these thoughts have at least been stimulating. Feel free to respond.
Shatz, David. "Skepticism and Naturalized Epistemology". Naturalism: A Critical Appraisal. Notre Dame. 1993.
I agree that we cannot rationally compel the committed skeptic to agree that we actually have knowledge. But that alone doesn't prove that our beliefs lack warrant. That's why I previously focused on the stronger skeptical claim that the justification required for knowledge is impossible. That's a more threatening claim, but one that - as we've seen - the externalist can rebuke.
If I understand him correctly, Rex wants us to address the more moderate skeptical position which holds that we contingently lack knowledge. Rex's skeptic grants the externalist claim that IF our commonsense realism is true THEN our beliefs amount to knowledge. But he denies the antecedent.
What grounds does he have for this denial? It sounds awfully dogmatic -- surely a true skeptic would instead remain agnostic about the ultimate nature of external reality, rather than bravely asserting our commonsense beliefs to be false. That is, he should allow that the antecedent might well be true for all he knows. Hence, granting externalism, the consequent might just as well be true. That is: the rest of us might well have externally justified knowledge, for all the skeptic knows. The careful skeptic will not go so far as to deny us knowledge. He will merely refrain from granting it.
We cannot compel the skeptic to accept our position -- but nor can he compel us to his. We have a dialectical stalemate. This won't worry the externalist. He can still claim to have knowledge. Maybe he's mistaken, but again: maybe not. (Note that it would be question-begging to ask externalists to refrain from making claims that they cannot show are justified. That would be precisely to insist on internalism!)
To be perfectly clear, here is the situation according to externalism:
(1) If realism is true, then we have knowledge.
(2) If realism is false, then we lack knowledge.
(3) It cannot be shown whether realism is true or false.
Realist externalists will further claim:
(4) Realism is true.
Our moderate skeptic grants 1-3, and is agnostic on 4. None of 1-4 has been shown false. The realist externalist emerges unscathed.
Rex brings up the vat-theorist, and suggests that "we would want to object that this fellow has no warrant for his hypothesis." Realist externalists will agree: the vat-theorist's beliefs are objectively false, unreliable, or what have you. That doesn't imply that our beliefs are in the same sorry state. Whether they are or not is a contingent matter, and depends on the external world. (The vat-theorist can defend himself in exactly the same way, and there's nothing wrong from his perspective in doing so. Realist externalists should grant that his view, like the skeptic's, is rationally tenable. They think that what makes him wrong is the external world.)
We may grant that "the externalist has no argument whatsoever for the claim that his beliefs ARE reliable." (Only an internalist would care.) To suggest that this shows the externalist's beliefs to be "laughably without warrant" is completely question-begging. Remember, the externalist holds "warrant" to consist in objective reliability and such, and he hasn't been shown to lack this.
So really, I don't think Rex has two objections here at all. The second one is shot through with internalist assumptions from start to finish. Dialectical skepticism, concerned as it is with what can be shown rather than what is objectively the case, won't much interest the externalist. This just leaves us with the first objection: that externalism is a poor theory of justification.
(In a future post, I'll suggest some internalist reasons for preferring common-sense realism to vat-theory.)