Here are some philosophical questions that I happen to be interested in (or have been interested in, in the past). "Are beliefs functional states?", "What makes our knowledge of our mental states particularly authoritative (if it is)?", "What is the best formulation of a causal theory of reference?", "How much mathematical knowledge can usefully be thought of as logical knowledge?", "Can one give a cogent neoHumean account of the notion of a scientific law?". And there's lots more where they came from -- all highly abstract conceptual questions. And in engaging with these very abstract questions (just as with mathematicians or scientists engaging with their abstract questions), I'm a very long way indeed from dealing with anything that engages with my sexuality. So surprise, surprise, you won't learn anything much about that from reading what I've written on those topics. Sexuality just doesn't come into it. And so it is with an great deal of what is written by a great number of philosophers....

As I've noted here before , we should surely distinguish loving someone from being in love with them. I might delight in the "sheer goodness and well being of" my daughter, miss her presence, especially when I'm feeling low -- that's evidence of love, but not of being in love. It is only too easy to be in love with someone you don't really love in Charles's sense (which is why I don't think his reply will do as an answer to a question about being in love). You can be obsessed, lustful, unable to get the other person out of your mind, your heart leaps at their glance, you are wildly jealous of glances bestowed elsewhere, but for all that you don't really care for the other in the right way, or delight in their well-being etc. ("If you really loved her", we might have to say to the man in love, "you wouldn't treat her like that.") Being in love, as Romeo memorably says, can be a "madness ... a choking gall and a preserving sweet". Proust is depressingly good on this!

We surely need to distinguish between (a) bad conduct that happens despite the professed beliefs of the sinner (well, we are all human and our actions too often fall short of our own ideals, whether religiously framed or more secular), and (b) bad deeds that result from someone following through the prescriptions of a loathsome form of religion. So when people behave vilely to homosexuals precisely because of some crabbed fundamentalist Christian beliefs, or think it is acceptable to kill apostates because caught up in some fundamentalist Islamic cult, then indeed we can rightly find the particular beliefs that lead them to appalling behaviour to be intolerable. By their fruits you shall know them.

It is rather difficult to believe that you have correctly describe your assigned task -- is it really to write at length about the notion of being in the Sophist without consulting any commentaries or interpretative essays? Well, not to beat about the bush, that project strikes me as simply ludicrous . You need all the help you can get if you are to work your way into a text some two and half thousand years old (in fact, I take it you are relying on a translation which has already made some interpretative moves that themselves raise issues): it is just absurd to pretend otherwise. Unless, I suppose, the point is to reveal to you the impossibility of the enterprise and make you appreciate that relative beginners need the commentators and the philosophical interpreters -- but then that is a pretty dumb way of getting you to see what is already an obvious truth.

Isn't it the other way about? Only a small number of philosophers would not maintain the distinction! For as you remark, lots of truths aren't useful in any ordinary sense (e.g. there is a fact of the matter about whether the number of grains in the rice jar yesterday was odd or even -- but the truth one way or the other is no use now to man or beast); and lots of claims which are strictly false can be useful (quick and dirty approximations that do us well enough. So to tie the ideas of what is true and what is useful together will need, for a start, bending the idea of the useful into something fairly remote from its common-or-garden sense, and we will also probably have to be pretty revisionary about what counts as true, in a way that few philosophers will be happy with.

We can also sometimes prove non-derivability results by purely "combinatorial" arguments. Here's a well-known toy example, due to Douglas Hofstadter. Consider a derivation system which uses just the symbols M, I, and U which can be combined to produce strings of symbols in any way you like, e.g. MI, UMIIM, IUUUUU, etc. The rules of our system are as follows: If a string ends in I, you can add a U to the end. For example, from MII you can "infer" MIIU. If a string starts M, you can "double" the rest of the string (i.e. change Mx, to Mxx). For example, from MIUI you can infer MIUIIUI. You can replace any occurrence of III with a U. For example, from MUIIIU you can infer MUUU. You can delete any occurrence of UU. For example: from MIUUUM you can infer MIUM. Question: Can you start with MI as an "axiom" and derive MU, using the rules 1 to 4? Answer: You can't. I'll leave you to work out why that is so (or to Google the proof!). But here's a hint and a comment. The hint is:...

Obviously not! Imagine a world with just three particles in it (not in a straight line). One particle stays fixed, the other two move slowly apart for ever (along the line joining them). The arrangement of the three particles in this finite-matter world -- the size and shape of the triangle formed by the particles -- is always changing and never repeats.

As a footnote, I'd perhaps want to press for being more careful with the distinction between loving another person and the state you are in when you fall in love with someone. After all, you can love someone without being in love with them: that's how most of us -- other than Oedipus -- are with our mothers! And it is only too easy to fall in love with someone you don't really love -- you are obsessed, lustful, can't get them out of your mind, your heart leaps at their glance, but you don't really care for them in the right way. ("If you really loved her", we might have to say to the man obsessively in love, "you wouldn't treat her like that.") But indeed, it doesn't seem that you have to get up close and personal either for genuine caring or to engender more obsessive states.

Let's see if I'm understanding. You hook up with someone whom you really like and who really likes you. There's a considerable sexual attraction. The hormones are more than buzzing and you are of an age when it is only too natural to want to start a sex life (and you are old enough for it to be legal). She is more than willing and is sending all the right signals. You fancy her like mad. And wow, it happens! Erm, well excuse me if I don't see your problem! Rash? Well, what is life without a few rash adventures along the way? But actually this wasn't particularly rash (unless zero contraceptive precautions were in use)! Just unplanned, but still mutually wanted and enjoyed. But that makes it sound to me a pretty good way to get things started, compared with the usual alternatives. Not weeks/months of old-style (or not so old-style) stressed fumblings towards "going all the way". Not some regrettable anonymous shag with a half-willing very drunk girl at a party. Just a happy experience with someone...

Isn't this far too like e.g. the question "Is enjoying pornography immoral?" In that case it all depends what exactly is in question: a bald yes/no answer would be hopelessly insensitive to the great variety of materials that fall under the very sweeping term "pornography". My impression -- and I hasten to cheerfully admit to lack of expertise! -- is that "BDSM" is similarly used as a pretty sweeping term that also can be, and has been, applied to a pretty wide variety of activities. So here too, a bald yes/no answer is surely likely to be inappropriate. Moral philosophers will need to know quite a bit more about just which sorts of activities in what sorts of contexts are up for evaluation before they can proceed to say anything sensible.