and which do you think is the right thing to do? [in most situations]. How do you make the choice? The thing that moves you to choose one way over another is the third thing I'm talking about; our moral intuitions; our sense of oughtness. Without it the stronger instinct would simply win each time.
I really can't give specific answers to such general questions.
Most of morality itself is either directly instinctive or derived from instincts.
But it doesn't really matter. I just feel like I have this mistrust of my impulses. A compliment from an unnattractive girl is nice, but a compliment from an attractive girl and I'd be on cloud 9 for weeks! What's that about?! Why do humans have a bias towards attractive people? It just seems so misguided and unfair. But that's just one of many problems in my head right now. You don't have to answer these questions btw, I'm just babbling.
There's nothing fair about initial physical attraction. The urge to reproduce is powerful (at least in the great majority of people), and instinct tells you to look for a mate with certain characteristics. Waist-to-hip ratio, youth, a certain shape of jaw and chin, a certain amount of facial symmetry--all of these things boil down to indications that the female is in good health, fertile, and likely to be able to bear many healthy children.
No one can help what they feel. Advertisers, as an example, take advantage of this by usually using the most universally sexually attractive (based on actual math) models to sell their products. If they're doing a product comparison, you may note that the male model holding up the competing product will be invariably shorter. We are programmed to sympathize with and in general to be favorably inclined towards sexually attractive people. Mountains of data support this. It's even the case when we don't feel sexually attracted to them, like a straight guy seeing another guy.
The thing is to recognize your instincts for what they are and not let them (entirely) guide your decisions.
When it comes to pretty girls, experience helps greatly with this. For a start, a girl's prettiness is
not a good indicator how much fun she is in bed--and let's face it, when you see a pretty girl part of your brain is thinking 'woohoo, sexy times!'. How pretty she is doesn't tell you what spending time with her would be like. It doesn't tell you how smart she is, or how interesting. It doesn't tell you if she's likely to cheat on you with your best friend, or a whole host of other things.
