Do these two sentences mean the same thing?- a) If I feel better tomorrow, I'll go out. b) Unless I feel better tomorrow, I won't go out.

I'd say that they have different meanings. I interpret (a) as implying that your feeling better tomorrow is a sufficient condition (all else equal, presumably) for your going out, whereas (b) implies that your feeling better tomorrow is a necessary but maybe not sufficient condition for your going out. That is, (b) seems more cautious, more hedged: (b) allows that you may not go out even if you do feel better tomorrow. Compare: (c) If you feed your pet goldfish, it will flourish; (d) Unless you feed your pet goldfish, it won't flourish. Given how easy it is to overfeed a pet goldfish, (c) is doubtful: your pet goldfish may not flourish even if you feed it. Given that pet goldfish depend on being fed, (d) isn't at all doubtful.

I'm 16 and have been studying philosophy for awhile. My question is when does a statement reach the point of 'absurdity'. For example, of the two statements, 1) My dog ran around the yard. And 2) My dog ran around the block with a big purple hat and green trousers. Number 2 seems the most likely not to have happened or seems 'ridiculous' by those who hear it. At what point does a statement cross the line of making logicalls sense to pure ridiculousness?

All else being equal, "My dog ran around the block wearing a big purple hat and green trousers" is far-fetched and unlikely to be true. But I wouldn't classify it as absurd in the logical sense, i.e., as making no logical sense. On the contrary, I think I can imagine (i.e., mentally picture) that amusing scenario. Now, if you were to claim that your dog ran around the block wearing colorless, entirely green trousers, I would classify your statement as logically absurd in the sense that it's logically self-inconsistent: it's logically impossible for anything, including trousers, to be both colorless and entirely green. So I'd say that something like logical self-inconsistency is the mark of a statement that has crossed the line into genuine absurdity. It's great to hear that, at 16, you've already been studying philosophy. I hope you'll keep doing so!

Why is the sorites problem a "paradox"? Isn't it fundamentally a problem of definition?

The sorites problem is a paradox for the reason that any problem is a paradox: it's an argument that leads from apparently true premises to an apparently false conclusion by means of apparently valid inferences. I don't think it's fundamentally a problem of definition, because the concepts that generate sorites paradoxes would be useless to us if they were redefined precisely enough to avoid sorites paradoxes. Take the concept tall man . In order to make that concept immune to the sorites, we'd have to define it in terms that are precise to no more than 1 millimeter of height, because a sorites argument for tall man exists that involves men who differ in height by only 1 millimeter. But defining a tall man as (say) a man at least 1850 millimeters in height would mean that in many cases we couldn't tell whether a man is tall without measuring his height in millimeters. Given the impracticality of taking such precise measurements in the typical case, we'd likely stop classifying men as "tall" and ...

Is there really a strong distinction between understanding what a proposition means and believing or disbelieving it? It strikes me that if I believe a proposition while my opponent does not, one way to explain the disagreement is to say that he misunderstands either that proposition or some related proposition. And so if we really did both understand all of the propositions in question, we'd have to agree about them as well.

I'd say that in many cases there's indeed a difference between grasping a proposition and believing the proposition, i.e., believing it to be true. To take a well-known example from mathematics, Georg Cantor believed that the Continuum Hypothesis is true, whereas Kurt Gödel believed it's false. Both were brilliant mathematicians; I see no reason to think that their disagreement arose from either man's misunderstanding the proposition in question or some related proposition. But not all cases are like that. Consider the proposition that all bachelors are unmarried. Anyone who fails to believe that proposition, I'd say, fails to grasp it, because grasping the proposition implies believing the proposition. At any rate, I can't make sense of the idea that someone could grasp that proposition without believing it.

Person A receives a large amount of money. Being selfless, he doesn't want to keep the money and sends it to person B. Unfortunately, B is also selfless, and sends the money back to A. A then sends the money to C. Fortunately, C is selfish and keeps the money. Can there be selflessness without there being selfishness?

I think so. Consider the example you gave. A's selflessness (her generosity, anyway) is manifested by her sending the money to B, whether or not B ends up accepting the money. Now, if A somehow knows that B will return the money immediately and is counting on B to return it, then A's selflessness is only apparent rather than genuine. But otherwise, I see no reason why A's action can't be considered genuinely selfless, whether or not the recipient in fact keeps the money. Further, I see no reason why C must be deemed selfish just because he accepts the money: it might be that, through no fault of his own, C desperately needs the money. What I think genuine selflessness does require is scarcity: if a particular resource is available to all in unlimited supply, then no one can genuinely make a gift of that resource, let alone a selfless gift. So I don't think there can be selflessness in heaven, if heaven is as it's described by various religions.

how many branches of philosophy are there, and why is language picked apart so meticulosly?

At least 33, to judge from the Areas of Specialization (AOS) listed here: Less facetiously: There's no non-arbitrary way to give a precise answer to your question, just as with the question "How many branches of science are there?" Careful attention to language is essential because, among other things, only when we're careful about language can we tell which philosophical problem (if any) we're trying to solve or which philosophical question (if any) we're trying to answer.

I've been wrestling with this problem for some time. My question concerns the concept of 'possibility'. When one says that something is possible, they are saying that something might be but may not be as well. There is an uncertainty. And of course whatever it is cannot both be and not be at the same time. Now, when we say that something is 'not possible', we are saying that something is not and cannot be. There is no uncertainty and the term as used does not seem to be a true negation as is usually meant when the term 'not' is used. What confuses me, is that in when actually trying to negate the concept of possibility, such as when saying 'not possible', aren't we on the one hand saying that 'that which might be' is not, and on the other hand that 'that which may not be' is not as well, and therefore is (or could be)? What may be is not and/or what may not be is. Saying that something is not possible, in this sense, is the same as saying that it is possible, thus making the negation of the concept...

I don't think there's a deep puzzle here, as I hope I can explain. The kind of possibility that stems from uncertainty is usually called "epistemic possibility," often signaled in English by "may" or "might," as in "There may [or might] be life on other planets." We're far from certain that there isn't life on other planets, so there may [for all we know] be life on other planets: life on other planets is an epistemic possibility for us. There are other kinds of possibility, such as metaphysical possibility, but I think the general point I'll make applies to all of them. To deny possibility in this sense, to say that some state of affairs S isn't epistemically possible for someone, is roughly to say that he/she is certain that S doesn't obtain, or at least he/she knows that S doesn't obtain (if knowledge doesn't require certainty). So I'd say that, right now, my own non-existence is epistemically impossible for me, because I know (indeed, I'm certain) that I exist, for the reason Descartes gives...

My dictionary's definition of "definition" is an "exact description of a thing". The definition doesn't contain an exact description of a thing, it only mentions it, so it doesn't qualify as a definition. Paradox?

I'm intrigued by your suggestion that there may be a paradox here, but I'm having trouble reconstructing your reasoning. As far as I can tell, your reasoning relies on the premise that any definition must contain whatever it defines . But I'm not sure that premise is plausible. defines "walrus" as follows: "a large gregarious marine mammal ( Odobenus rosmarus of the family Odobenidae) of arctic waters that is related to the seals and has long ivory tusks, a tough wrinkled hide, and stiff whiskers and that feeds mainly on bivalve mollusks." That definition (more precisely, the definiens ) doesn't contain the word ("walrus") being defined, which is good: otherwise the definition would be unhelpful. Nor does the definition contain a walrus; we'd need a cage to do that. Instead, the definition gives us a string of words meant to pick out the walrus from among other things. If it's a genuine definition, then the principle on which it seems you're relying is false. But I may...

In several answers in AskPhilosophers, philosophers say that some uttered words express emotions, feelings, sensations and the like (but you always use the word "express"), and that this is not the same as some words saying or stating that such emotion (etc.) occurred. So you make a big difference between expressing and saying (or perhaps stating). For instance, "ouch" expresses pain, while "I am feeling pain" states that such pain exists. Sometimes you say that expressing cannot be true or false, but statements can. It is very difficult for me to understand this difference. I understand that "ouch" is much more immediate than "I am feeling pain", and that "ouch" is slightly humorous, and there may be other differences, but basically these two sentences just say the same thing. They convey the same basic information and both can be used to give a false information. Would you be so kind as to explain me what is the difference between expressing and saying (stating) in cases where what is expressed can be...

A very interesting question touching on complicated territory! Probably the best response I can give is to recommend the SEP article on "Pragmatics," available at this link . I think you'll find it contains lots of information highly relevant to your question.