Philosophers who talk about knowledge usually focus on knowing a fact ('knowing-that') or having an ability ('knowing-how'); but 'knowing-a-person' different from either of these types of knowledge. One one level, it is not very difficult: you could truthfully answer 'yes' to the question of whether you know Alexander George if you had say met him and had a few good conversations. And 'Know-who', as in 'Do you know who Alexander George is?' is even easier: you don't have even to have met him. At the other extreme, if 'getting to know Alexander George' required a kind of comprehensive knowledge-that of all the facts relating to him, you will never make it. Fortunately, you can make progress on getting t0 know someone without impossibly having the full story about them, if you can find out more about their personality and about what they think. And I am more optimistic about the possibility of that than you seem to be.

One part of the answer is the 'why-regress'. As you know, whenever someone answers your why-question, you can almost always ask why about the answer, and this seems like it can go on forever. But I don't think that shows that we never explain anything. If I ask why my car won't start, telling me that my battery is dead can be a good answer, even if you don't tell me why my battery is dead (though I might like to know about that too!).

I'm with Richard here: the truth of a proposition cannot be an illusion. In an illusion, the proposition is false. But there might nevertheless be a sense in which truth could be an illusion, if we think that there are representations when in fact there aren't any. This is paradoxical territory, but for example there is a line of thought from Wittgenstein, articulated in Saul Kripke's Wittgenstein on Rules and Private Language , according to which our thoughts do not have determinate content. No determinate content, no determinate proposition, so no truth. If that were the situation, but we thought that there was truth here, we might (truly?) say that truth is an illusion.

Here is one reason why one limited form of competition in philosophy (and many other areas of inquiry) is good. Faced with a philosophical problem, our best bet is to propose a possible solution, criticise it, and on that basis to try to improve it, or improve on it. But almost all philosophers are better at criticising other people's ideas than their own. So competition yields an epistemic advantage. Karl Popper proposed this kind of methodology of 'conjectures and refutations' as the key to inquiry, especially in science. Although there is a lot I would criticize (sic) in Popper, I think he is right to emphasise the importance of trying to find the weak points in the best ideas people can come up with.

It's hard to generalise about this. For example, is the certain thing a new kind of thing or not.? If not, withholding judgment may be the right answer. For example, I have no reason whatsoever to believe that the house next to mine has a red ball in it, so I probably should simply withold judgment: maybe it does and maybe it doesn't. On the other hand, if I have no reason whatsoever to believe that in the house next to mine there is a kind of animal quite different from any known animal, I probably should deny that it exists. Why should we deny the existence of radically new kinds of things when we have no evidence for their existence? Part of the answer may be that our principles of reasoning incorporate various kinds of preferences for simplicity. In the case of things, this is known as Occam's razor: don't multiply entities beyond necessity. It is not obvious why, taken as a principle of denial rather than a principle of withholding judgment, this is a good principle, but many would say...

One way one might try to distinguish automaticity from the unconscious would be to say that of these two types of state, only unconsious states are representations, are about anything. For example, my unconscious desire to be reunited with my childhood sled (cf. Rosebud in the great movie Citizen Kane ) is about something -- a sled -- while all that neural processing involved in controling my breathing is not a representation of anything, though my life depends on it.

Someone who didn't know how to learn anything could not be taught anything. So for people to be teachable, they must already have some ability to learn, an ability that was not taught to them. But that doesn't mean that people can't be taught to learn various things, just that unless people already know how to learn some things, they won't be able to learn other things. By the way, in the Meno, Plato's fabulous dialogue, Socrates seems to accept that learning as normally understood really is impossible, because you either already know the thing, in which case you aren't learning it, or you wouldn't recognise it even if you came across it, and so wouldn't learn it either. His view is that what we call learning is really recollection.

How do you even know they have the question? But if what you are asking is how philosophers know that an answer they propose is in fact the right answer, then the question is big and complicated. Here is a short partial answer. Philosophers are good at finding contradictions between different things we are inclined to believe, and one way they test their answers is seeing whether they can be integrated into a consistent system. Consistency is no guarantee of truth, but inconsistency is a guarantee of falsehood.

This is the classic skeptical worry about 'spectrum inversion'. Not allphilosophers would agree (surprise, surprise), but I am inclined to saythat you can't know for sure. And I agree with you that the fact thatwe agree about the name of the color doesn't help much. At the sametime, I think we may have good reason to believe that similar coloursare experienced similarly by different people, insofar as we have goodreason to believe that they go through similar neurophysiologicalprocesses when they are exposed to light of the same frequency.

I very ordinary example of a question without an answer might be a question with a false presupposition. Suppose the question is whether you have stopped beating your dog, where in fact, kind soul that you are, you never started beating your dog. In that case I think we still have a question, but although it has a good reply, it has no answer.