I don't know the answer to your question, but since this topic interests you, I would recommend you take a look at the skeptical traditions generally categorized as Pyrrhonian and Academic skepticism. One famous device you might use to think about these questions is called Agrippa's trilemma. An ancient chronicler of skepticism called Sextus Empiricus reports that one Agrippa posed the following problem: Justifications for knowledge claims seem problematic because knowledge claims must be justified by other claims, just as premises are needed to justify a conclusion. How are the justifying claims to be themselves justified? Either (1) they are self-evident and self-justifying--but this seems wrong and little better than making assumptions, which justify nothing. Or (2) the supposed justification starts an infinite regress where the supporting claims get justified by other claims and those claims get justified by still other claims, ad infinitum--but an infinite regress doesn't seem like justification. Or...

You won't be surprised to learn that what these terms mean is a matter of some controversy among scholars. Some bits, however, have achieved general agreement. Pyrrhonian and Academic skepticism mark two branches of ancient skepticism. David Hume and other moderns also used the terms. One way to discriminate them is institutionally. Not long after Plato's death his school just outside of Athens, the Academy, became dominated by skeptical thinkers. The philosophical work engaged by those thinkers came, of course, to be called Academic skepticism. The major texts by which Academic skepticism, however, came to be known to the modern world were not those of philosophers leading the Academy but, rather, of the Roman philosopher, Cicero. His books, Academica and De natura deorum , became highly influential. Pyrrhonian skepticism, by contrast, follows a line rooted in the thought of a man named Pyrrho, who lived in small town of Elis, on the other side of Greece. Pyrrho was not associated with a...

Absolutely.

A very good question. At first blush philosophers' practices might seem arbitrary, indeed. There are a number of considerations, however, that might help those practices seem more sensible to you. First off, it's important to define the concept of "intuition". You might be surprised to learn that the concept has a long history and that it has a number of meanings. In one sense it means something like the way the intellect apprehends things. Philosophers who find ancient and medieval philosophy convincing still do give that sense of "intuition" considerable credence. Secondly, it means something like, "our basic moral commitments." Many ethicists still appeal to moral "intuitions" in this sense to guide and limit moral deliberation. On a third, scientific level, intuition might be thought of as something like an educated guess. It's true that philosophers don't think of "intuition" in this sense as source of "knowledge"--though they are likely to respect its standing as a way of generating...

Yeah, these are the kinds of questions that lead many of us to "Argggh!" They're also the kind of questions that I approach with a great deal of trepidation because they are knottier than knotty. So, please understand that what I say here by the nature of this kind of exposition will be very rough and overly simplistic. You'll also probably find more than a few of my colleauges to disagree. But anyway, let's barrel right on with it. I don't think you can be absolutely sure that what you see is what's "real"--though you really ought to take some time to parse out what you mean by that word because it's LOADED. I take it that you mean by "real" something like what's out there independently of us. In a sense, actually, my best shot is that what you or we see isn't exactly real in that sense. Do remember that old Aristotelian question, "When a tree falls in the forest and there's no one around to listen, does it make a sound?" Well . . . get ready . . . almost yes, but no. No in the way that...

Hume once described skepticism as a "malady that can't be cur'd" (a colleague of mine says it's like herpes in that way), and perhaps it's the same with solipsism. The suspicion that it can't be fully refuted depends upon the concern that any reasons brought against it might be gounded simply in the contents of one's self or one's own mind--and that one doesn't fully know oneself or one's own mind. So, pehaps the world and the people in it one experiences are something like dreams or hallucinations. Perhaps the ideas and languages one encounters are one's own invention. Perhaps one's mind has the power (and exercises the power) to create or imagine everything we experience and think and feel, but that power remains hidden from consiousness. One of the most persuasive strategies for subverting solipsism in recent years has been to show that the very thoughts and language in which it is expressed require others to make those thoughts and words meaningful. So, the very existence of the thought and...

"Knowledge" might be divided into four types: (1) theoretical knowledge (knowing that X); (2) practical knowledge (know how); (3) familiarity (knowing someone); and (4) moral knowledge (knowing what's right). 1. Emotion alone doesn't seem able to produce theoretical knowledge. In fact, emotion often obstructs it. 2. Emotion alone can't make it possible for us to know how to do something--e.g. drive a car or play the violin. But it can be a necessary condition for us knowing how, for example, to play music well or for knowing how to manage people psychologically (as an effective manager, parent, or politician might know how to do). 3. Emotion might be the result of familiarity, but knowing someone isn't made possible by emotion alone. 4. The very idea of moral "knowledge" is a strange one, but one might say that knowing what the right thing to do in a given situation might be said to be determined through feeling. But I doubt it would make sense to say that emotion alone yields moral...

The reliability of witnesses is a terribly interesting issue. You may find it surprising to learn that according to the directors of the Innocence Project at Northwestern University (a project that investigates cases of erroneous criminal conviction) the false testimony of eye witnesses is the single biggest reason for false convictions. How is it that so much of our life rests upon something so unreliable, something with no foundation? Well, perhaps we have no other choice. That is to say, we find ourselves subject to belief because it's our human nature or human condition to believe, not because we have what Descartes called a fundamentum inconcussum , an unshakeable foundation. (Hume would agree.) And perhaps there's a positive side to the skeptical insight. Perhaps we're better off acknoweldging that our beliefs may be (or are) without ultimate foundations. Why? Because those who believe that they have apprehended ultimate foundations tend to be dogmatists, and on the basis of absolute...

It's a great question, and the way you pose it raises a number of fascinating issues. About the concern whether "anything" is true, I assume you mean any truth claim. Things can be said to be "true" in certain contexts ("That's a true Rembrandt"; "That way is true north"; "Mine is true love"), but typically in philosophical contexts it's statements that are either true or false. Here I'm inclined to say that it's not unwise to withold some measure of judgment on virtually any truth claim. If by "sure" you mean, impossible to doubt, then I think we might be better off not trying to achieve it. Skeptical philosophers like Sextus Empiricus, Hume, and Montaigne have in various ways advanced ideas like this. On the other hand, Ludwig Wittgenstein and other philosophers have held that in many contexts it's simply senseless to raise doubts our to try to raise doubts. I must say, I've not been persuaded yet by this strategy. But, as Hume reminds us, we must be as diffident of our doubts as of our...

Let's assume that one can't "know" that there are other minds. Does solipsism follow? It may be possible, but remember that from ignorance only ignorance follows. From not knowing whether there are other minds it follows only that we don't know whether or not there are other minds. There may not be, but on the other hand there may. Perhaps the sceptic points out that we must accept our finitude, that while we may go on to develop sciences, theories, truth claims, instiutions of various kinds, etc., we must remember that it's possible that we might be wrong, that things might not be as they seem, that our claims may not be fully grounded. Perhaps our relationship with others and the world isn't best understood in terms of "knowledge." Perhaps that's just the human condition. Keeping this possiblity in the back of one's mind vaccinates against hubris.