Toward the beginning of my graduate student years — I think during my very first year at UCLA (1984-5) — Saul Kripke came to town & delivered what I came to think of as his “Nozick-bashing lecture,” which he also delivered at several other places. I don’t think this material was ever published, which is too bad, because much of it seemed extremely valuable. Of course, you should take that judgment with a grain of salt, since it’s coming from me, and I was only a first-year graduate student who had not yet seriously studied any contemporary epistemology (other than religious epistemology) at the time I formed the opinion. I continue to be of that opinion even now, but I can’t be certain if I’m remembering the talk very well: I may be attributing to it material I read or heard elsewhere at about the same time. But others who heard the talk, and who were in a better position to judge, seem also to think that it’s a shame that it was never published.
(In her “Naturalist Reflections on Knowledge,” Pacific Philosophical Quarterly 65 (1984): 315-334, Ruth Millikan writes this in a note: “If you would say that her belief constituted knowledge, let me recommend S. Kripke’s devastating critique of R. Nozick’s Philosophical Explanations (Cambridge, Mass.: Harvard University Press 1981), lecture delivered at the University of Connecticut, December 17, 1984; critical review forthcoming in NOÛS.” As I read this, it’s saying that Kripke’s lecture, or at least closely related material, was to be published as a critical review of Nozick. But I think that now, more than 20 years later, we’re still waiting….)
Kripke’s lecture was very important to me, personally. As I indicated above, I was not yet a serious student of epistemology when I heard it. In particular, I hadn’t yet even read Kripke’s target, Nozick’s Philosophical Explanations. Kripke’s lecture is what got me interested in epistemology. (Curiously, though I had not yet read the Nozick material itself, and my only exposure to it at the time was Kripke’s lecture, which Millikan was right to call a “devastating critique,” I nonetheless walked out of the lecture thinking (among other things) that there still seemed to be something importantly right in the Nozick. That turned out to be an important thought in my subsequent work.)
Because of its importance to me, I remember — or at least seem to myself to more-or-less rightly remember — more about this talk than any other I heard so long ago (and indeed more than most talks I’ve heard even very recently). And when the occasion calls for it, I try to write down what I remember, as well as I can remember it. So, for instance, one point (a side-point, as I recall) Kripke made that was quite striking to me at the time was that, while we often speak as if knowledge is something quite difficult to attain, in some settings (I’d say “contexts” here, except that then people would start rolling their eyes!) we use “knows” as if true belief were all that’s required to know something. And I tried to convey the case (involving one of his favorite characters, Nixon) that Kripke used here as well as I could remember in a longish note (note #9) of my “Assertion, Knowledge, and Context” (Philosophical Review, 2002; penultimate draft available on-line in word & pdf formats at my list of on-line papers here).
Another point (again, a side-point, as I recall) Kripke made that was quite striking to me concerned the dream argument for skepticism. I was reminded of this just recently when I read a post by Jonathan Ichikawa over at Fake Barn Country on “Why dream skepticism is special”. Like Ichikawa, Kripke was struck by the fact that, unlike the skeptical hypothesis that one might be a brain-in-a-vat, which can seem very far-fetched, the hypothesis that one might be dreaming can seem a very substantial possibility, because we actually do dream very often. And if I’m remembering right, Kripke had a quite effective way of illustrating the importance to the force of the skepticism the hypotheses can inspire that this difference can make…
As best I can recall, Kripke asked us to imagine that we discovered a race of aliens who were much like us, except that they never slept & never dreamt. Or maybe he asked us to imagine that we never slept & never dreamt, but then we discovered a race of aliens who slept & dreamt as we actually do — just about every night. I’m not sure which way Kripke did this. In any case, what this all led up to was the question of how those aliens would react (or how we would react, on the second version) once they found out about our dreaming habits: “So, every night, you guys go slipping off into this state of ‘sleep’ for several hours, during which time you have several episodes of this ‘dreaming’, where you think you’re perceiving the world, but in fact, it’s all illusion. Man, you guys just don’t ever know when you’re really perceiving things!”
I don’t recall how Kripke actually explained the upshot of this difference, so here I may be going off a bit on my own, but this imagined skeptical outburst has a very different (& more menacing) flavor from when a skeptical thesis is merely based on some “skeptical hypothesis” like the BIV scenario, which seems just a “bare” possibility, as we might put it; a possibility for which we have no similar positive basis for thinking it might really be the case; a possibility which, if I can be excused for putting it this way, someone just “dreamt up.” Things can be quite different with dreaming-inspired skepticism. As one of Ichikawa’s commentators, “Ethical Werewolf,” puts it in the discussion thread to Ichiakawa’s post: “If I understand the research correctly, we spend about 90 minutes a night dreaming. Assuming a 960-minute day, nearly a tenth of our sensations are dream-sensations! It’s as if we live our entire waking lives on the outskirts of Fake Barn Country!”
We didn’t have to dream up the dream possibility.
I hope to have a bit more to say on dreaming-based skepticism soon. But for now, I just wanted to get a little Kripke (if I’m remembering right!) out there.