In thinking about your question, we might recall the conversation between Humpty Dumpty and Alice in Through the Looking Glass . At one point, Humpty Dumpty exclaims "There's glory for you." Alice protests that she doesn't know what he means. Humpty Dumpty smiled contemptuously. "Of course you don't -- till I tell you. I meant 'there's a nice knock-down argument for you!'" "But 'glory' doesn't mean 'a nice knock-down argument'," Alice objected. "When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean -- neither more nor less." "The question is," said Alice, "whether you can make words mean so many different things." "The question is," said Humpty Dumpty, "which is to be master -- that's all." Philosophers often distinguish between the semantic meaning of a word -- its assigned meaning in language -- and the speaker meaning of a word --what the speaker intends to mean by the word. Most of the time, if we want to...

Following Kant, we might distinguish hypothetical imperatives from categorical imperatives to answer your question. Hypothetical imperatives tell us what we should do given our aims. Categorical imperatives tell us what we should do, full-stop, regardless of our aims. Moral imperatives (our moral duties) are taken to be categorical imperatives, and they can be expressed using "should": You should not murder, you should not lie, you should show compassion to others, etc. But hypothetical imperatives can also be expressed using "should". If we're talking to someone who wants to go to law school, we might say, "You should take the LSAT." If we're talking to someone who wants a good challenge, we might say, "You should read some Kant." If we're talking to someone who wants to be a model, we might say "You should get plastic surgery." If we're talking to someone who wants to commit murder quietly to avoid getting caught, we might say, "You should use poison." None of these "should" statements are...

I wanted to respond to the suggestion in your question that if a term is vague it is thereby "pointless" -- that doesn't seem right to me. For example, although the term "bald" is vague -- we can't specify the precise number of hairs a person must have (or not have) to count as bald -- the term is by no means pointless. Perhaps there are some borderline cases where we don't know whether to call someone bald or not (Jason Alexander? Bald? Or just balding?). But that doesn't mean that there aren't plenty of clear cases: Howie Mandel, bald; Suri Cruise, not. [Aside: see here if you're concerned about bald babies.] And so the term "bald" is perfectly useful in everyday speech. [Another aside: interestingly, Wikipedia lists Jason Alexander among their famous bald people , but I'd call him a borderline case. The entire list seems suspect to me, anyhow -- why is Matthew McConaughey on the list? But philosophers are well-represented: Foucault, Whitehead, and Wollheim all make the list.] ...

Many statements that have the apparent form of a question do not function as interrogative speech acts. For example, in many contexts, if I say, "Can you please close the door?," my remark really functions as a command rather than as a question. (Likewise, my declarative statement, "You haven't closed the door" can function as a command in certain contexts.) So, if you really aren't looking for answers or information from your students, perhaps your remarks in class that have the apparent form of questions function in some other way. Perahps as commands -- when you say, "Can anyone think of a reason that ... ?" you might be instructing them to think about the issue. Or perhaps as declarative statements -- you might simply be imparting information to them. But, given what you said above, it's not clear to me that your apparent questions don't really function as questions. The fact that your students are free not to answer, and that you don't blame them for not answering, does not mean...

It sounds to me as if you've answered (at least part of) your own question -- if you don't know what you're talking about when you read the speech aloud, then how could you be said to understand it? Suppose you're a native English speaker and you don't know any other languages. A French speaker could write out, perhaps phonetically, a sentence in French and you could practice reading that sentence aloud until you could read that sentence flawlessly, but that won't make you understand it. Whatever understanding is, you would lack it. Perhaps in the case where you read the speech about nuclear physics aloud, there are many words that you understand, and perhaps even whole sentences. But for any part of the speech that you are functioning essentially as a parrot -- where you voice something without knowing what it is you're talking about -- you lack understanding.

One way to put the questions is in terms of intention -- what role does the intention of the speaker play in establishing the meaning of the speaker's words. At one extreme is the position Humpty Dumpty stakes out in the works of Lewis Carroll In a conversation with Alice, Humpty Dumpty says "there''s glory for you" and when Alice expresses puzzlement, he explains that by "glory" he means "a nice knockdown argument." On Humpty Dumpty's theory of meaning, the intention of the speaker seems to be all that matters for meaning. In response to this, there's a strong temptation to say: but "glory" does not mean "a nice knockdown argument"! So at the other extreme, someone might argue that speaker's intentions don't matter at all for meaning -- words have meaning independent of any individual speaker's intentions, and the speaker locks on to that meaning when making an utterance. You might think that the right answer lies somewhere inbetween these two extremes. A lot of philosophical work is...

Perhaps you've seen it, but William Safire had a column in the New York Times magazine about this a few years ago. Language changes all the time, and words/phrases come to have new meanings. I agree with you that this particular change is frustrating philosophically, and it does make me kind of grumpy when I hear it, but that said, I'm not sure that there's much we can do about it. It seems to me that it's already too late -- in ordinary use, "beg the question" has already come to mean something like "raise the question." In philosophical discussion, of course, we can and should retain the original use of this phrase. I think of it much the way I do the terms "valid" and "sound". In ordinary conversation, it's perfectly acceptable to say "she makes a valid point" or "her point is sound", where both "valid" and "sound" are being used as synonyms for "true" or "plausible". But when discussing and evaluating arguments, we reserve the terms "valid" and "sound" as technical terms to apply...