top of page

On the meaning of 'knowledge'

[Philosophical notes from 2005.] Reading a collection called Contemporary Debates in Epistemology (eds. Steup and Sosa) for class. I'm halfway through the Dretske reading, which argues against the principle of closure (closure = the idea that if S knows that P is true and knows that P implies Q, then, evidentially speaking, this is enough for S to know that Q is true).

I think all the controversies over the definition of knowledge and the definition of the terms one uses to define knowledge and the question of how one knows when one has knowledge and so on are misguided. Knowledge is a semi-meaningless idea. Its definition, vaguely stated, should be unproblematic: one has knowledge, in the strictest sense, when one has a true, justified belief the truth of which one is certain. (Even “Gettier-style counterexamples”[1] and “Goldman’s barn case”[2] don’t pose a problem to this definition, because in both cases one can say that the belief in question, in being accidentally true, isn’t completely justified (due to the believer’s not having all the relevant information) and is therefore not, strictly speaking, known.) But the ideas of ‘certainty’ and ‘adequate justification’ cannot themselves be defined except in ways that beg the question, such as ‘certainty = the absence of doubt’. (What is doubt?) Thus, knowledge can’t be clearly defined, and skepticism is ineluctable.[3]

In any case, the idea of ‘knowledge’ in the strictest sense (I know, absolutely, that the earth moves around the sun) is, practically and philosophically speaking, irrelevant. Who cares whether (we know that) our beliefs, or any beliefs, are incapable of being wrong? It doesn’t matter! The corollary of this fact is that skepticism[4] too has no great relevance; the impulse to defeat it arises from the valueless longing for some kind of unattainable psychological security. It’s fanciful and shouldn’t be taken very seriously—but, nevertheless, it can’t be refuted. Descartes’ evil demon exists as a permanent, though ridiculous, possibility.


‘Knowledge’ has a subjective and an objective aspect. On the one hand, it’s a mental state—a strong version of ‘belief’, namely certainty—while on the other it presupposes that the proposition of which one is certain is objectively true. Now, both sides are open to attack. ‘Certainty’ is the absence of doubt; but what does this absence mean? If I see a spot and say “I see a spot”, is it possible for me to doubt it (by asking whether I know it)? Yes and no. Inasmuch as it occurs to me that I may not be seeing a spot, that I’m being “massively” deceived in my sense experiences, I do doubt it. My doubt may be unclear and apparently ‘empty’, but since the proposition’s negation occurs to me, there is, in a sense, doubt. I think ‘In some metaphysical world, I may somehow be wrong’. But my doubt can’t be effectively grasped, as it can when I doubt whether I’ll ever get married. I can easily understand what it would be like to remain a bachelor; I can’t understand how I could be wrong about the spot. Nevertheless, since the ‘abstract’ possibility of my wrongness flits across my mind, I do in a sense doubt the proposition. So I don’t have complete certainty, and I don’t have knowledge.

What about the person to whom it doesn’t even occur that his belief might (somehow) be wrong? Assuming such a phenomenon is possible (which I doubt[5])—i.e., assuming he really does have “certainty”—does he have knowledge? No, because his belief might be false. Can a belief ever be determined as true beyond a doubt? In the most rigorous sense, no. But, again, the doubt will often appear meaningless.

Does my loose definition of doubt seem perverse? Probably. But it’s necessary: how else can one account for the existence of these sorts of questions? Clearly philosophers have some kind of doubt—and all kinds are incompatible with knowledge in the strictest sense.

The idea of ‘justification’ is problematic also. Surely I’m justified in saying “I see a spot”, but am I justified in saying “I know I see a spot”? If what I wrote above is true, then I’m not (because (1) I doubt the proposition and (2) there’s no way to determine conclusively its truth-value). But it’s odd to say the first proposition is justified and the second isn’t, because in saying the first is justified I’m effectively saying it’s true, which would appear to mean both that I know it’s true and that its truth-value can be determined (and therefore that the second is justified as well). But do I know the first is justified? As soon as I add the word ‘know’, I become doubtful. That’s always the way it is, in every context! I consider myself justified in saying the table is brown but not necessarily justified in saying I know the table is brown. Why? Because my uttering the word ‘know’ introduces an element of doubt (really confusion) that has its origin in the meaninglessness of ‘know’ (as used in this context).


Ever since skimming On Certainty I’ve been attracted to Wittgenstein's idea (it's implicit at least) that most of the paradoxes and intuitions and counter-intuitions about knowledge can be explained-away/reconciled by hypothesizing that there are two kinds of knowledge: the ‘commonsensical’ and the (almost meaningless) philosophical. The duality, I think, arises from the schism in our nature between the animal mode of apprehending reality and the ‘intellective’ mode. Expressed in linguistic terms, it’s the ‘ordinary language vs. philosophical language’ dichotomy.

--Contemporary epistemologists are confused. They’re going about the problem(s) in the wrong way. As I've said before, the only way to a solution is to cut through the difficulties, to get below them, as Wittgenstein tried to do.


Dretske’s strategy, more or less, is to argue that an abandonment of closure is the only way around skepticism. But his arguments are muddled. He thinks that “closure tells us we have to know there is an external world in order to see there are cookies in the jar [that we’re looking at]”, but he’s wrong—in a sense. I can “see (hence, know)” there are cookies in the jar without knowing there’s an external world if I define cookies not as mind-independent objects but simply as ‘those things I see (which may, after all, be mind-dependent)’ (because in this case my knowing there are cookies wouldn’t imply there are mind-independent objects). On the other hand, if I define cookies as mind-independent (as Dretscke seems to do), then yes, I do have to know there’s an external world in order to know there are cookies, because the existence of mind-independent cookies logically entails there are mind-independent objects. If I can’t know there are mind-independent objects, and I define cookies as such, then—oh well—I can’t know there are cookies. Dretske may be right that an abandonment of closure is the only way around skepticism, but he’s wrong that closure can be abandoned. Doing so is tantamount to denying logical entailments.

–This is what Dretske’s position comes down to: ‘Even though q follows from p, and I know that p is true, it’s possible that q is false’.


I have no qualms about saying, “I know there’s a desk in front of me”. The ‘I know’ part seems unnecessary and strangely meaningless, but I feel entitled to it. However, if someone asks me, “But do you know there’s a desk in front of you? Do you really know it?”, I’ll start to have doubts. I’ll think, first, ‘um, yes, I really know it!’ But then I’ll think, ‘well, who knows, I guess there’s a tiny possibility I’m hallucinating or the victim of some massive deception’. –In short: I know there’s a desk here, but I don’t know it. The emphasis changes the word’s meaning—even though it remains, on some level, meaningless.


The reason that absolute certainty is impossible (indeed, inconceivable (hence meaningless)) is that (self-)consciousness can’t help positing an external world (or rather, the externality of the world), i.e., an external truth. Because it’s both of itself and of an object—a world—‘opposed’ to it, it’s aware that this object is outside of it, and that it can never have direct, intuitive access to the interior of this object. The division between self-consciousness and the world (which is also that between self-consciousness and itself, since it’s aware of two things at once) is what makes negation not only possible but implicit in the nature of consciousness—and this permanent presence of negation, as I wrote earlier, is why we can’t overcome doubt. As long as we can imagine an alternative, we can doubt. When I ‘naïvely’ affirm a proposition, as in the above example, I’m concentrating on what I’m ‘naïvely’ aware of. But when I ask myself whether I truly know I’m right, I’m concentrating—possibly in a confused, half-conscious way—on the dualism between myself and an objective reality. I’m concentrating on the possibility (really the reality) of negation.


Am I justified in my belief that Bush went to New Orleans after hurricane Katrina had devastated it? Yes. I read it in the Times and saw photographs. Do I know he went? No. It’s possible the information I read was mistaken. And anyway, I’m not in a position to decide whether I know it; only someone who has immediate evidence of, or access to, the truth can decide that (because knowledge isn’t knowledge unless the belief is true). –Now, that my belief is completely justified as a belief but not as knowledge—i.e., that I’m being entirely rational in being convinced of its truth even though (I recognize that) its falsehood is a possibility—is a strange contradiction, which shows that, in a sense, the concept of knowledge is superfluous, or at any rate, not useful.


What insane instinct drives philosophers to go to preposterous lengths to find a way around skepticism? It’s like they shudder even to think about it. Nerds. Says Dretske: “[skepticism] is a last resort. If the only choices are skepticism or the rejection of closure, then—too bad—we had better learn to live without closure.” Yes, it’s better to throw aside logic than to accept (the impossibility of refuting) skepticism. Sure.


(Some) skeptical hypotheses are really quite muddled. It may indeed be the case that a Cartesian demon is deceiving me by making me think that the things I see constitute an external world or whatnot, but it’s nonsensical to suggest that I may ‘actually’ be a brain in a vat [to use an example common in the literature]. The I that I am is right here; the word ‘I’, as applied to myself, has no meaning outside my immediately existing, immediately self-present self here in this world. I can’t be two beings at once: I can’t be this self and a brain in a vat somewhere in the ‘background’ (behind the curtain, as it were). It may be the case that a brain in a vat is producing all my experiences, but I am not that brain. –How terribly obvious this is! Yet philosophers seem not to take it into account.

So then do I know I’m not a BIV? Meaningless question. Because certainty is meaningless, and because I don’t have direct access to truth (and in order to know something, I have to have access to metaphysical reality). The most I can say is that my being a brain in a vat is inconceivable. –Again, the question doesn’t seem meaningless because ‘know’ has meaning in certain (unphilosophical) contexts.

But it seems that if I don’t, after all, know something, then I’m doubting it—even where (as here) doubt has effectively no content and no force. So am I doubting the proposition that I’m not a BIV? I guess so—but only in the sense that I recognize that a metaphysical world of truth may be hidden from me, a world in which, perhaps, logical contradictions (like the one in question) may somehow be true.

[1] Example of such an example: “Suppose your colleague Brown tells you that he owns a Ford. You infer: (1) Someone in the office owns a Ford. You believe (1), and your belief is justified. Suppose, however, that unbeknownst to Brown, he went bankrupt. The bank confiscated the Ford. But another colleague Smith happens to own a Ford. Then (1) is true. Yet it seems that you do not know it.” Right. Because my belief wasn’t justified enough for me to claim to know it.

[2] “S is driving in the country and stops in front of a barn. Unbeknownst to S, S is looking at one of the few genuine barns in an area spawned with barn facsimiles. The facsimiles are so realistic that if S had stopped in front of any of them, S would have been tricked into thinking he was looking at a real barn. But by luck S has stopped in front of one of the few real barns left in the area. The standard intuition is that S does not know he is looking at a real barn, because he could easily have had the same belief while looking at a facsimile.”

[3] It's possible that that conclusion doesn’t follow from the premise.

[4] The thoroughgoing kind that questions even ordinary knowledge.

[5] It could be argued that in affirming a proposition, one ‘implicitly’ recognizes the possibility of its falsehood. Would that be doubt? In the (almost meaningless) exclusively philosophical sense, yes.

Recent Posts

See All

Thanks for submitting!

bottom of page