I think there can be cases in which reflection can destroy knowledge, yes. Most epistemologists these days are fallibilists, which is to say that one can know something even if what warrants their belief does not guarantee certainty--could be (but is not) mistaken in some way. So one way someone could lose this sort of knowledge would be by reflecting on certain other intuitions most of us have about vulnerability to error. For example, can you really KNOW that something is true if there is even a one in a million chance that you are mistaken in believing that thing? I can easily imagine someone with low enough cognitive self-esteem--"Hey, maybe I'm wrong !!!" or "I'm so stupid, why should I believe that I am getting anything right, even though it really seems in this case I have it right!" and so on--that one could actually talk themselves out of knowing something because one would come up with some reason for thinking they were (or might be) wrong when in fact they had it right all along and...

I just responded to a question almost exactly like this one. Please see my reply to that other question.

Who the hell do you think you're talking to??? (Just a joke! But one I would like you to take seriously for a moment. After all, if you really were a solipsist, you wouldn't expect an answer to your question from anyone, right?) It may be that solipsism cannot be refuted as such. (After all, if one is dedicated to holding the truth of solipsism, the one attempting to refute it is put into...well...a bit of an awkward position!) But there may be another angle: What should we think of a theory that not only nullifies all morality (you can't wrong something that doesn't exist), but also all discourse (who are you talking to?), and which cannot even be accepted in living one's life (go ahead and make believe that other consciousnesses don't exist, and see if you can make that work!). If a theory cannot be lived , how good a theory can it be?

Descartes imagined that he had found something that could not be doubted in what is known as his " cogito " (a shortened form of the Latin expression " cogito ergo sum, " which means "I think, therefore I am." You can see the intuitive strength of this: What would it be like to think that you were thinking, but be mistaken about that? (How could you be mistaken--because even to be mistaken, you'd have to be thinking something , right?) Others have supposed that certain mathematical or logical truths are also indubitable (such as 2+2=4, or "if p then p"). But even Descartes thought that mathematical and logical truths are dubitable in some sense--even if we can't imagine what it would be like for them to be false, Descartes argued that we can imagine being so badly deceived (by an immensely powerful evil demon, say) that it could be that something we couldn't imagine being false might still actually be false. And some philosophers have also said that we can provide some reason...

I believe the oldest expression of this injunction appeared as an inscription at the shrine at Delphi. The inscription itself is no longer extant, but it is referred to in ancient sources as having been one of the things displayed at the shrine. See Plato's Phaedrus 230a. Many subsequent authors liked to use this expression, and each may have meant something somewhat different by using it. Socrates' own use of it seemed to mean something like, "Be aware of your own ignorance!" We can only speculate about what thoe who inscribed the words at Delphi might have meant, but I would surmise it was something like this: "Know that you are merely a mortal, and do not presume to be in any way the equal of a god!"

It really depends upon what it is that one is supposed to come to know this way--and it will also depend upon just what one takes the requirements of knowledge to consist in. Some epistemologists have argued that we have a kind of privileged access to knowledge of our own mental (including emotional states) themselves. These philosophers would think that at least one sort of knowledge we could attain through emotions was knowledge of those emotions themselves--knowledge that we were in such-and-such a state at a given time (for example, knowledge that I am angry right now, or sad). But others do not think that we necessarily know our own states in any privileged way--we might really be angry, but not know that we are, or we might think we are angry, but actually not really be. As for other sorts of knowledge, such as knowledge of the world outside of our own consciousness, I am inclined to think that we cannot "acquire knowledge through emotions only." As important as the emotions are in...

That will really depend, won't it, on what you take the standards of knowledge to require. If by "knowledge" you require certainty (as what are called "infallibilists" require), I think you will find that human beings are capable of precious little in the way of knowledge. On the other hand, if you think that knowing something is compatible with fallibility (as "fallibilists" claim), then I don't see why social relations and social environments are not areas in which we can have knowledge. Even if we are fallibilists, however, I think it is reasonable to suppose that knowledge of some subjects might be difficult to achieve, might take substantial study and observation, and so on. In terms of what falls under "social relations," I think it will be easier to know that Jones is my student, for example, than that Jones is my friend. Here's something I know about this subject: It is very difficult to know that a given person is my One True Love!

Two answers come to mind: (1) If we grant that mathematics is known with certainty, I think the same can be made for the laws of logic--for example, if P, then P... or either P or not-P. (2) I can think of some reasons for supposing that even mathematical truths and the laws of logic aren't known with certainty. For one thing, axiomatized systems of reasoning (such as the logic and mathematics) are able to undergo modification, as a result of new discoveries--for example, the Euclidean axiom that the shortest distance between two points is a straight line is not an axiom in Eisteinian geometry (since gravity wells curve space). For another thing, I don't think we can automatically infer, from the fact that we find it impossible to imagine the falsity of something, that our beliefs about that subject must be true. Why couldn't we be so bad off that we are incapable of imagining what's true, and capable only of imagining some falsehood as truth? Descartes takes this issue up in his ...

I certainly do not think that our only view of reality can be via experience by our own physical senses. Human beings are magnificently complicated cognitive beings, capable of using not just our immediate senses, but also memory, interpersonal communication, abstract reasoning, and other processes by which to form beliefs. Of course, some of these are more reliable than others: wishful thinking is highly unreliable; vision is much more reliable. But the use of expert testimony--especially when corroborated by other kinds of evidence (as for example, regarding the Taj Mahal, where you can also find photographs of it, accounts of it in narratives, etc.) can also be highly reliable--otherwise, most of us wouldn't read newspapers, right? So, I think my answer to your (1) should be clear--I think you can have very reasonable beliefs about the existence of the Taj Mahal even though you have never actually visited it. Indeed, some of those very reasonable beliefs might lead you to decide to visit...

I'm not planning to send this to Analysis , but it seems to me there might be such a case, at least under certain conceptions of knowledge (where I am not proposing the case as a counterexample to the conception). Suppose we think (as I actually do) that knowledge requires the application of appropriate epistemic virtues. Being fallible (at least for the most part, as far as we can tell), one such epistemic virtue is epistemic humility. The one with epistemic humility is a fallibilist, and accepts that she could be mistaken (but actually is not). But suppose she actually has a kind of knowledge about which she is, in fact, infallible. Even so, she thinks she could be mistaken about what she knows. But that is false, she cannot be mistaken. However, were she not to think she could be, she would be epistemically immodest, thus not virtuous, and thus wouldn't know. Might that be such a case?