I had a brief chat with a work colleague today about the nature of reality and our perception of it. Essentially, his contention was that because we all basically agree on our external physical reality (e.g. when I hand him a cup of tea we both agree that I've just passed him a cup of hot tea), there must be an external reality because we both seem to agree on what it's like. If there wasn't such an external reality and we didn't essentially agree on it, he pointed out, we wouldn't be able to even ask for a cup of tea because my idea of what a cup of tea actually is would be totally different (or at least different enough to make meaningful communication difficult). Therefore, he concluded, it's common sense that we must be talking about and looking at the same "real" things and that we both experience them in the same -- or very similar -- way. Age-old philosophical problem solved! But it can't be that simple. So my question is what are the main problems with this "consensus" view of reality? Or, to put...

I've seen only one of the Matrix films, the first one. You might ask your colleague how he can be certain that things in our world aren't as they're portrayed in that film: that is, you and he merely believe you're conversing in the ordinary way about an ordinary teacup, when in fact you're both hooked up to a computer that's simulating the conversation, the teacup, and your surroundings. Is there some internal indication, something about the way things feel to him during such a conversation, that rules out a Matrix-style simulation? What could that be? Granted, neither you nor your colleague are at all inclined to believe that you're living a simulated existence, but that's just how the Matrix wants it!

In the light of the current state in philosophy, do skeptics still get an upper hand? Can we really know anything with certainty?

I'm going to refer you to two websites. At the PhilPapers Survey , you'll discover that only 4.8% of "target faculty" said that they accept or lean toward skepticism. Among specialists in epistemology (the theory of knowledge), that figure increases to 9.4%, but it's still small enough to suggest that philosophers in general don't think of skepticism as having the upper hand once the reasons for and against it are examined carefully. For detailed discussion of your second question, you might start with the SEP entry on "Certainty" . I hope you find these resources helpful.

what are the requirements for knowledge?

You'll find your question very thoroughly taken up in the SEP entry on the analysis of knowledge . As you'll see there, some philosophers go so far as to reject your question on the grounds that knowledge can't profitably be analyzed into other concepts. Enjoy!

Is it possible for someone to produce knowledge simply based on reason alone, without any emotion?

I see no reason, in principle, why not. If knowledge were not possible without emotion, then no emotionless computer could achieve knowledge, which would come as a shock to the proponents of artificial intelligence (AI). Nor do I see anything in the concept of knowledge itself that rules out knowledge based on reason alone without any emotional content or associations. I don't mean to say that emotion can't play an essential role in some kinds of knowledge, only that I can't see how emotion would be essential to every kind of knowledge.

After studying philosophy, I am now so skeptical of everything that I no longer know what I should believe in. I have no idea whom I should vote for in election or whether I should be voting at all, what religion I ought to believe in if any at all, why I should bother getting married, or even why I should bother getting out of bed in the mornings. Have you found that philosophy leads to more skepticism and knowing nothing rather than clarification?

You asked, "Have you found that philosophy leads to more skepticism and knowing nothing rather than clarification?" It may be that you didn't sacrifice any knowledge that you previously had. Your philosophical reflection may have revealed to you that you didn't in fact know what you took yourself to know before you engaged in it. Maybe you had confident beliefs about whom you ought to vote for, etc., and even the confident belief that you knew whom you ought to vote for, etc. Examining your grounds for those beliefs caused you to lose confidence in them. In Plato's dialogues, Socrates is portrayed as frequently showing people that they didn't in fact know what they confidently took themselves to know. That's an important discovery one can make about oneself. Even if your philosophical reflection has made you question some of your previously held beliefs, it doesn't follow that you ought to become a wholesale skeptic. Philosophical reflection should include scrutinizing the grounds for...

I'm completely new to philosophy so please excuse my simplistic question - is it really possible to 'know' anything (aside from apriori knowledge if this exists)? I'm not convinced that it is. PR

You've asked a venerable question in epistemology, the area of philosophy that investigates knowledge and related concepts. My short answer would be "Why not?" In ordinary life, we confidently take ourselves to know things. I'm confident that I know I have hands. I'm confident that I know I'm now awake and typing at a keyboard. I'm confident that I know the surname of the current U.S. president. And on and on. What reason do I have to abandon that confidence? Now, over the centuries, various skeptical arguments have been offered that challenge the claim that we know the things we take ourselves to know. Those arguments are well worth investigating. You might start with the SEP entry on skepticism, available here .

Although I can experience feelings of fear, pride, and shame in my dreams, I cannot experience the sensation of sharp pains in my dreams. Right now, I am pinching myself and I am experiencing pain. How does this fail to prove that I am awake?

If I'm genuinely skeptical about whether I can know I'm awake, then I can't properly take as given the data you cite in your question, namely, that I can experience fear, pride, and shame while dreaming but not sharp pain. Trusting those data would presuppose that I can tell when I'm awake and when I'm dreaming. So the proof would be persuasive only if I can already know when I'm awake, in which case why would I need or seek a proof? By the same token, however, I can't properly appeal to the convincing dreams I've had in order to conclude that I can't know I'm not dreaming right now. For when I claim that I've had convincing dreams -- i.e., non-waking experiences that I mistook for waking experiences -- I also presuppose that I can tell when I'm awake, which runs counter to the skeptical conclusion of the dream argument.

On 'Cogito Ergo Sum' If this statement means that the only thing I can know to be true is that I exist, then that means I don't know if the reasoning used to deduce this statement is logically sound. What evidence do we have that our reasoning is to be believed? The only reason that we trust our reasoning is because have reasoned that it is trustworthy. We trust our reasoning because we trust our reasoning. I know that I came to this conclusion with the same human logic as cogito ergo sum, so this conclusion must be equally invalid. Humans are imperfect-> humans 'invented' logic-> logic is not necessarily perfect. "I do not know if I know anything." Please fix any broken logic I have, or point me in the direction of relevant articles on how my thinking was outdone hundreds of years ago. Thanks

I don't mean to criticize Prof. Reid's excellent scholarly response on behalf of Descartes. But it's worth pointing out that the reasoning from the Second Replies that he attributes to Descartes is more complex and dubitable than the inference from 'I think' to 'I exist' is to begin with. In the quoted passage, Descartes seems to make a universal generalization about human psychology based on a single known case, his own. That generalization can't be more reliable than inferring 'I exist' from 'I think', or else we wouldn't need an empirical science of psychology. Likewise, the psychological claim that a two-step inference is always less reliable than a one-step thought is a claim that's got to be more dubitable than inferring 'I exist' from 'I think' or calculating the sum of 2 and 3. It would have been better had Descartes denied the very intelligibility of doubting the simplest inferences we make -- or at least had he challenged a skeptical opponent to make sense of such doubt.

My question concerns epistemology and "post-modernism". Why do philosophical books on epistemology fail to discuss the problem of how one knows what a text means? Postmodernism have raised various questions about the possibility of how one knows what a text means, but the only books on epistemology I've seen talk about things like foundationalism, coherence, Gettier counter-examples, etc, but miss talking about Derrida's deconstructionism, and the positions of people like Fish and Foucault. Furthermore, who are the philosophers working on epistemology "answers" to postmodern thinkers? Is there a must read rejection of postmodern scepticism? I am aware of important critiques amongst Christian thinkers (e.g. D.A. Carson's "The Gagging of God") but I suspect there must be more philosophical responses.

I discern the following meaning in your text: You're asking why epistemology books generally don't cover postmodernist arguments for skepticism about our knowledge of a text's meaning. One reason might be this: Arguments for skepticism about our knowledge of a text's meaning are merely applications of more general skeptical arguments about, for example, our knowledge of other minds. If so, then it's probably best to focus on the more general skeptical arguments to see if they're good enough to warrant applying them to specific cases such as textual meaning. A second reason might be this: Arguments for skepticism about our knowledge of a text's meaning arise mainly from philosophical issues outside epistemology per se -- for example, issues in philosophy of language and philosophy of mind. If so, then you'd be more likely to find them discussed in books on those topics. Some analytic philosophers have engaged with postmodernist thinkers in detail. Two examples come to mind: (1) John Searle...