What do you mean by an "objective" reality? Do you mean a reality that exists outside of my mind? It isn't obvious to me that there is any better answer than that given by the British philosopher G. E. Moore: I know that I have two hands, and my hands are certainly not inside my mind but attached to my arms. So, well, there you go. There are all kinds of questions about what, exactly, Moore's argument shows and what it doesn't show. But one of Moore's points, I take it, was that the question whether there exists a world outside my mind is one that is to be answered, if at all, in terms of whether there is anything outside my mind, and my hands are as good an example as any there could be. And that just seems right. Regarding the second question, nothing guarantees that our view of the world is correct. I can imagine, just barely, that I do not have two hands but seem to myself to have two hands because of some weird brain injury. I suppose that is, in some sense, possible. But the mere fact...

I would suggest that the problem here is that the term "Solipsism" is being applied to more than one view. Solipsism, as I understand it, is the view that only I exist. This is obviously true. Nonetheless, my experience contains streams of sensations that I am able to organize, for my convenience, into sequences I call "persons", and I have sometimes encounted some of these "persons" discussing another view that they call "Solipsism", which they claim is the view that only they exist. I find this both confusing and amusing. These "persons" don't exist at all, except as streams of sensations, and so they certainly don't exist in the way I do (as I am not a stream of sensations). So it's not at all clear to me what view this other Solipsism is supposed to be. Is it that only the streams of sensations that constitute them exist? What a silly view! As if sensations could exist without someone whose sensations they were! But, well, I suppose it's not surprising that the view should be so silly, since...

The standard way to resolve this problem is to distinguish explicit from implicit beliefs. Suppose, just for illustration, that believing that p , in the explicit sense, is having a sentence that means that p written on a blackboard in your head. So believing that snow is white, for example, is having a sentence that means that snow is white written on a blackboard in your head. (You can think of this as meaning, roughly, that this information is explicitly stored in memory somehow.) Now, suppose I have the sentence "I have two arms" written on my mental blackboard and that I also have the sentence "two is less than three" written on my internal blackboard. Suppose, further, that I am capable of simple reasoning. Then, if the question were to arise, it seems reasonable to suppose I would conclude, from those explicit beliefs, that I have fewer than three arms. So we might say, in this case, that I implicitly believe that I have fewer than three arms. And so on. It is not an easy...

I find this question somewhat puzzling, because it assumes that the only point of studying some subject is to "find the answers". I very much hope that is not true, because I am quite sure that I'll never know the answers to many, if any, of the big questions I spend my time studying. That does not, however, mean I am not learning something along the way, even something important, and making some kind of contribution. I think the same is true of the study (or better, the practice) of religion. I don't expect ever truly to understand life, the universe, and everything, but that doesn't mean I can't come to understand something about it.

There are a couple different issues here that need to be disentangled. One concerns what philosophers call "testimony". It's clear that one way of knowing something is being told: If you can't know that the earth is round because you were told, then, as you note, very few people know that the earth is round. Now, as always in philosophy, there is much disagreement about how why one can come to know something by being told. But most people would agree that testimony is only a means by which knowledge may be transmitted : If you tell me that p , and I now know that p , you must already have known that p . Maybe you were told that p by someone else. But the chain has to bottom out somewhere, with someone who knows that p "of h'er own knowledge", as a lawyer might say, that is, not because s'he was told. Testimony therefore seems a distraction here. The problem of religious knowledge concerns how one might know (say) that God exists otherwise than by being told. If...

Here's Frege's way of making this point: Now these distinctions between a prioir and a posteriori, synthetic and analytic, concern, as I see it, not the content of the judgement but the justification for making the judgement. ...When a proposition is called a posteriori or a priori in my sense, this is not a judgement about the conditions, psychological, physiological and physical, which have made it possible to form the content of the proposition in our consciousness; nor is it a judgement about the way in which some other man has come, perhaps erroneously, to believe it true; rather, it is a judgement about the ultimate ground upon which rests the justification for holding it to be true. ( Foundations of Arithmetic , section 3) Frege attaches a footnote in the middle of the first sentence in which he says that he means "only to state accurately what earlier writers, Kant in particular, have meant by" these terms.

It's important to avoid a certain confusion here. One might say, about Alex's argument, that if there does not exist at least one true statement, then of course "There is a pen on my desk now" is not itself a true statement; hence the argument is circular. Of course, the first part is true; but the conclusion does not follow. For the argument to be circular, the claim "There is at least one true statement" would need to be used in that argument, but it is not. What is used in the argument are simply (analogues of) the following two premises: (i) snow is white; (ii) if snow is white, then "snow is white" is true. Alex claims to know (i) by observation; it's less obvious how we know (ii), but one who claims to know it seems on pretty firm ground. From (i) and (ii), then, it follows that "snow is white" is true and so, by a simple logical inference, that there is at least one true statement (viz, "snow is white"). To challenge this argument, one must either challenge (i) or (ii) or one must find...

As has often been mentioned here, one cannot "prove" very much, if "prove" means something like: Establish beyond absolutely all doubt, reasonable or otherwise. It simply does not follow, however, that one cannot know very much. To suppose otherwise is to suppose that one can know only what one can "prove", and there is simply no reason to believe that. That said, it may yet be (and I take it, indeed still is) a puzzle what exactly it is to know something.

There are many serious questions along these lines. The redness of your rock seems to be a property the rock has as it is in itself, but early modern philosophers, beginning with Descartes but perhaps most famously Locke, questioned whether that is so. There are many sorts of alternative views, but perhaps the most common nowadays is the so-called dispositional theory of color: Colors are relational properties, on this view; for a thing to be red is for it to tend (under normal conditions) to cause certain kinds of sensations in perceivers. If that is right, then there is a way in which color is only in our minds. See, as usual, the Stanford Encyclopedia for more on this issue. Note, however, that this issue isn't really best formulated as one about whether we know the rock is red. The issue is one about what it is for the rock to be red. On either view, we can and often do know such things. Or, at least, whether we can or do is an independent question.

The last question asked here can be treated more generally. When we speak of two people's having the same belief, what we mean is that they believe the same thing , where what they both believe is, say, that Margaret Thatcher likes hot dogs. Belief is usually regarded as a relation between a person and a "proposition", which characterizes the "content" of the belief. So to say that two people have the same belief is to say e.g. that both Bill and Sue stand in the belief-relation to the same proposition, say, that Bill has been unfaithful. Knowledge, too, is a relation between a person and a proposition. So the fact that Bill knows that he is unfaithful, whereas Sue does not, simply means that Bill stands in the knowledge-relation to this proposition, whereas Sue does not. There's no logical problem here, even though if is also true, as most philosophers think, that, to stand in the knowledge-relation to some proposition, you must also stand in the belief-relation. There is some controversy...