Advanced Search

If knowledge is defined as justified true belief, why is it necessary to include "justified" in that definition. If I have a belief that corresponds with an objective state of affairs, why doesn't that count as knowledge regardless of justification? In the Theaetetus, Socrates seems to consider it self-evident that if one forms a belief based on unreliable testimony, that belief is not knowledge even if it true. I don't see why this is the case. If a delusional person tells me it is going to rain tomorrow, and I form the belief (which happens to be true) that it is going to rain tomorrow, why would that not be considered knowledge? Especially if I can use that belief to successfully guide my activity in the world? One more clarification: I can understand why justification matters with respect to the psychological process of forming a belief. I am talking about the definition of knowledge, which is already presupposed to be true.

Different philosophers would answer this sort of question different ways, depending upon how they approach epistemology. On one sort of view, we might think that this is a question about the meaning of the ordinary English verb "to know". And in that case, there seems to be good evidence that English speakers are not always willing to describe someone as "knowing" something just because they believe it and it is true. For example, the Super Bowl is tomorrow. I know nothing about football, but suppose I firmly believe that the Seahawks are going to win. If they do win, would you want to say that I knew they would? A more interesting question, though, to my mind, is simply whether we think there is an important distinction to be made here, whether or not it is one that is made in English. And that, obviously, has to be decided by seeing what work "knowledge", in that sense, can do. It's not at all clear, actually, that all one's true beliefs can "successfully guide...activity in the world" in the same...

Could it ever be rational to come to a belief on the basis of evidence which is only accessible to oneself? I have in mind, for instance, people who claim to have arrived at a belief in god by way of some critically personal spiritual experience.

I think the answer to this has to be "yes". Suppose I have a sharp pain in my foot. On the basis of that experience, I form the belief that I have stepped on a nail. This belief seems to be justified (and so rational), and it is partly based on evidence available only to me (the felt quality of the pain). The idea that religious belief might be justified on the basis of religious experience has a long history, and some---Swinburne, possibly, but I don't remember for sure---have explicitly drawn the analogy to the role experience plays in the formation of belief.

I have been reading Robert Nozick’s Philosophical Explanations (a difficult text indeed) and have a question about his theory of knowledge; specifically, Nozick concedes to the knowledge skeptic that we cannot know, say, if we are a brain in a vat on Alpha Centauri (our experience of the world would be identical, says the skeptic, to what it is now, so we cannot know); but he then also notes that it does not follow that I cannot know, say, that I am typing on my computer. If I understand correctly, Nozick holds that my belief that I am typing tracks the fact that I am typing; I would not have the belief that I am typing if I were not typing. This, however, seems problematic to me; it seems to beg the question, i.e. assume the “fact” that I am typing is indeed a fact. Isn’t this what we precisely do not know according to the skeptic? What if I see a perceptual distortion, for example, a pencil wobbling like rubber when I place it between my thumb and index finger and quickly move it back and forth? My...

This doesn't seem at all clear. First of all, the argument assumes that, to know whether we know, on Nozick's account, we would have to know whether a certain counterfactual is true. But this isn't obvious. Water is H2O, but it doesn't follow that, to know whether something is water, you have to know whether it is H2O. Similarly, even if knowledge is (say) Nozick-style tracking, it does not follow that, to know whether you know, you have to know whether you track Nozick-style. That might follow if Nozick's account is construed as providing some kind of conceptual analysis, but even then there are issues that tend to go under the heading "The Paradox of Analysis". Second, even if the foregoing is waived, I don't see why we can't know "whether the subjunctive condition Nozick deems necessary for knowledge is fulfilled". Surely we do have lots of knowledge about possibility, necessity, and counterfactuals. Of course, the epistemology of modal knowledge is a vexed issue, but so is the epistemology of...

As commonly understood and reinforced here, 2 + 2 = 4 is taken as meeting the test for absolute certainty. This appears to be true in a formal or symbolic sense but is it true in reality? When we count two things as being the same and add them to two other same things do we really get four identical things? Perhaps, perhaps not; it may depend on one's identity theory. Do we know with absolute certainty when we have one thing and not two? What am I missing?

I don't myself have a view on whether 2+2=4 is absolutely certain. I suppose it's as certain as anything is or could be. But the question here is different. It's whether that certainty is undermined by doubts about what happens empirically. As Gottlob Frege would quickly have pointed out, however, the mathematical truth that 2+2=4 has nothing particular to do with what happens empirically. It might have been, for example, that whenver you tried to put two things together with two other things, one of them disappeared. (Or perhaps they were like rabbits, and another one appeared!) But mathematics says nothing of this. That 2+2=4 does not tell you what will happen when you put things together. It only tells you that, if there are two of these things and two of those things, and if none of these is one of those, then there are four things that are among these and those. It's hard to see how one's theory of identity could affect that.

Considering Descartes' malicious demon idea, is it possible that we could be manipulated in such a way so as all our beliefs are false? I'm thinking that we'd already need some true beliefs in order to have false ones. To be fooled into thinking that pig beards are shorter on Tuesdays I'd have to have true beliefs about pigs, beards, length, and Tuesdays for example. Can I infer then that the overwhelming majority of our beliefs must be true?

This kind of argument has been made by many different philosophers. Two that come immediately to mind are Ludwig Wittgenstein and Donald Davidson. Their considerations are broadly along the lines of: To have any beliefs at all about pigs, beards, etc, I must have some (mostly?) true beliefs about them. For Davidson, the argument involves considerations about what he calls"radical interpretation", the process of making sense of anotherthinker. But that just seems to me to answer the wrong question. The issue isn't about what's involved in making sense of someone. Maybe you do have to agree with the person about a lot of things to do that. The issue concerns what it is to have beliefs. Jerry Fodor has written at length about a great conflict between broadly "pragmatist" theories about the contents of beliefs and, uhh, non-pragmatist theories. According to Fodor's view, for example, being able to have beliefs about pigs involves being in the right kind of causal relation with pigs, and there isn't any...

How do we know we are not a computer program? In other words, some kind of video game? I know of the the brain in a vat argument but why suppose we have a brain at all? What if our "mind" is a computer only running a "human program" or some such thing? What if all sensation is just data in a computer and all "WE" are is just data in a computer? Any problems with this argument?

It's not obvious what the argument is here. Are we trying to argue that we actually are just avatars in a computer simulation? If so, then the argument seems pretty weak. Are we trying to argue that we don't know that we're not avatars in a computer simulation? Then., again, one wants to know what the argument actually is. It seems to be something like: We can't absolutely rule out that we're not avatars, etc, etc. And if so, then, yes, I agree that Putnam's brain-in-a-vat argument is actually pretty hopeless. But my own view, for what it's worth, is that the BIV argument doesn't actually have anything to do with skepticism. (I think it has to do with metaphysical realism, a very different topic.) But the deeper question, I think, is whether knowing that p actually requires being able to rule out the bare possibility that not- p , and not everyone would agree that it does, especially where skeptical scenarios are concerned. Have a peek, for instance, at Jim Pryor's paper "The Skeptic and the...

How much of epistemology boils down to semantics? Sometimes it seems as though all we're really doing is trying to decide which situations warrant use of the word "know"; nothing actually changes in practice.

This is a deep and important question. But let me first correct an apparent misimpression: namely, that, if the central questions of epistemology are semantic questions, then they are unimportant or uninteresting. On the contrary, semantics---the study of meaning---is an important subject in its own right, and it is arguably of central importance in any broadly "conceptual" investigation. So, to the question. This is much disputed nowadays. There are some philosophers who think that many central epistemological questions are, fundamentally, questions about the meaning of the verb "to know". This group includes so-called contextualists, like Keith DeRose, but also philosophers like Jason Stanley and John Hawthorne, whose view is sometimes known as "situation-sensitive invariantism". On these views, our odd reactions to many of the puzzle cases are due to aspects of the way the verb "to know" behaves, or to certain not so obvious features of the concept of knowledge. Contextualists generally hold that...

Is it possible to know something and not be able to express it?

Sure. I know how the grapes in my back yard taste, but I can't come close to expressing that adequately. I know how John Coltrane plays the soprano sax---with an unmatched genius and intensity---but there's not much else I can really say. And I know how it feels when I see my daughter smile. But if you want me to express that, then I'll have to resort to bad poetry.

As I understand it, people use the word "believe" when they are somewhat but not entirely sure of a proposition (e.g., "I believe that he likes cheese", as opposed to "I know that he likes cheese"). If a person "believes" a proposition p, does he KNOW that he BELIEVES that p? Is he absolutely certain that he believes a proposition of which he is just somewhat certain? Or does he BELIEVE that he BELIEVES that p? (Are there other possible formulations?) -ace

You are right that people usually use the word `believe' only if they are not entirely sure. If they were, then they'd say something else, maybe "I know that...", or "I'm sure that...", or just "...", all by itself. But it does not follow that "I believe..." MEANS "I'm not absolutely certain", etc. This point is due to H.P. Grice and is central to his work on `conversational implicature'. We also need to distinguish knowledge from certainty. It may likewise be true that people say "I know" only when they are fairly certain, but it does not follow that "I know..." means: I'm reasonably certain.... What knowledge is, well, that's a disputed question. But let's just pretend it's justified true belief. Then knowing is having a justified true belief, and you could know but not be certain you know, or even be very certain of something you truly believe but not know because you aren't really justified. Most (though not all) philosophers would hold that, if you know that p, then you also believe...

Recently an English reviewer of Richard Dawkins' book The God Delusion took Dawkins to task for writing outside his field, suggesting he stick to science. Is this a legitimate criticism? And are there any anti-religious theologians?

I'm guessing the review to which you refer is Terry Eagleton's in the London Review of Books . I sympathize with Eagleton's frustration, though I don't think he quite plays his cards right. Surely it is true that Dawkins would barbecue any theologian who decided to write a book on evolutionary biology without boning up on the subject, and rightly so. One does rather expect that an author will have some minimal knowledge about what he or she is writing about. But the point (my point, anyway) isn't that Dawkins isn't himself religious. The point is that there are lots of people who study religion, and they do so from many different points of view. Some of these people are my colleagues at Brown, and some of them are Dawkins's colleagues in Oxford. Many of them are religious, but some of them are not. And for Dawkins to write on this topic with, so far as I can tell, essentially no real knowledge of this work is intellectually dishonest, at best. I don't think a knowledge of Duns Scotus and...

Pages