In scenarios where the metaphorical glass is either half-full or half-empty, so to speak, are there any compelling rational reasons to come down on one side or the other? Or is a person's optimism or pessimism just a character trait independent of rational thought?

Well, there may be certain ontological commitments or implications of choosing one over the other. (This would be independent of one's "optimism/pessimism"...) For example, in the medievals there was extensive discussion about what constituted "real being" and what only seemed real, but was in fact either derivative or conceptual or negative being. So, for one example, it was argued that light is "real" while shadows, which SEEM real, can be "thought of" as if they were real, in fact are not: shadow is merely the absence of light. A lot could ride on this: all real being (for example) would require a cause of its being, while derivative or non-beings would not. So if there is light you need to explain what causes the light; but if there is darkness, you don't need something which "generates" darkness, since darkness is not a real existent, but the absence of the real existent. That being said, there is something to say for preferring the glass being half-full -- for then you are speaking of what...

Is it possible to rise above jealousy, what are the questions i need to ask myself to rise above it?

if you're asking 'can some people rise above jealousy?', surely the answer is yes -- i can't help but think, though, that this question is more in the domain of psychology than philosophy .... (unless you believe that a proper theory of the world could help here -- eg Buddhism, which teaches you to free yourself from all attachments -- I suppose THAT would help with jealousy! --) ... For something you might enjoy reading on the subject, have a look at Proust's Remembrance of Things Past -- it's the second or third book, which is the story of Swann's jealousy over a woman named Odette .... best, ap

My teacher claims that he is utterly emotionless; according to him, he isn’t clouded by emotions of any form, and has no emotional desire. He argues that any emotions he appears to possess are simply superficial occurrences, with the purpose of manipulating others. He argues that he is utterly objective and consequently, completely exclusive from any form of bias. My question is that surely somebody who objectively chooses to use logic over any form of emotional guidance and has “no emotional desire whatsoever”, is therefore exhibiting a desire in itself? Surely, if one assumes logic as their only form of reasoning, the logic must be based upon basic desires and principles, therefore denoting an emotional presence? I would be grateful if somebody could enlighten me!

I worry that framing the question this way begs the question -- you seem to assume that any 'choice' comes from or out of 'desire', but isn't that precisely what's at issue? I think we'd need to get a lot clearer on what a 'desire' is before we could answer the question in a satisfactory way ... For example, you seem to consider 'desire' a kind of 'emotion', but philosophers of mind typically would distinguish the two in various ways -- perhaps desires share a kind of 'qualitative character' or 'qualia' with emotions, but desires are typically characterized by having an object or content, one often expressible in words, in a way emotions are typically characterized as 'raw feelings' that may or may not have a specific object or content -- Once you separate desires from emotions, you then need to define desire in such a way as to make it clear that every choice comes from some desire ..... (Charles mentions Spock -- consider this thought. Suppose you could program a computer to do all sorts of complex...