I do wish people reading pieces like this would bear in mind that they have to be incredibly terse. I was given 600 words, which is much shorter than an undergraduate essay! It meant either concentrating on a very small aspect of the topic or stripping some of it down to mere summary. My first draft was about twice the allowed length. So it's a bit, um, galling, when I see comments in various corners of the internet that criticise what is not said.
I'm slightly surprised, though, that the bit about reason and desire seems to be creating some problems over at RD.net. It's very standard Humean stuff, but let's expand a bit. Our desires can't be justified in some ultimate way. X desires to have sex with women; Y desires to have sex with men. Neither desire is more rational than the other. What is rational or otherwise is how they go about it. If X thinks that a good way to get women to have sex with him/her is to vomit over their shoes, that's probably not rational. I.e., reason tells us that this gambit is not usually successful.
Reason enables us to find out stuff about the world, including about other people, which can be very useful in achieving our desires. Sometimes it's even rational to try to change our desires because reason tells us that it'll help us achieve our deeper desires. So rational reflection on our desires is important. We shouldn't act on our most immediate impulse but in a way that will work to achieve deeper desires. Hopefully, X's desire to have sex with women isn't going to turn X into a rapist, because X also wishes (desires) not to hurt people, not to use violence, not to breach useful social norms, etc. So X might be the sort of person, like most of us, who is motivated to charm and seduce but wouldn't even think of raping.
But our ultimate, deepest desires are simply things that we have. There's no way to appeal to us to try to change them except by appealing to even deeper desires that we have (in which case they are not our deepest desires after all). Unfortunately, a truly evil person, e.g. a vicious and cunning psychopath, may be doing nothing irrational - but such a person is a danger to the rest of us and must be stopped. It's rational for us to throw him or her in jail. Fortunately, most of us are not like that: we may not be angelically altruistic, but we are social animals who desire to help each other, etc. Think how you'd react in the street if an elderly person suddenly collapsed in pain. Even if you didn't know what to do, you'd want to help. Almost everyone - barring the stray psychopath - is like that.
Without desires (and, like Hume, I include here hopes, fears, values) we'd never do anything. We wouldn't even have a reason to find out facts about the world unless we either desired to know these facts for its own sake or we desired to know these facts for the sake of achieving our other desires. Eventually, reason alone always runs out as a source of motivation.