I discussed this recently elsewhere: https://utilitarian.quora.com/Utility-monsters-arent-we-all I'm glad I'm not the only one who's thought of this.
I used to think about self-proclaimed selfishness in this way all the time, but now I think I "get" the doctrine of selfishness. For instance, the answer to the first mischevous question is actually "because I get personal happiness from preaching selfishness, and that vastly overshadows any happiness I could instead get from a single person's altruism". The answer to own life vs. human species is "because a guilt-ridden life wouldn't maximise my personal happiness", and so on.
There's a solution I always thought of since young, that is instead of letting voters vote for a single candidate of their choice, let them assign each candidate a score and the representation will be defined by the total score of a party's candidates.
Perhaps it would be better to let voters rank the candidates instead, and assign each rank a well-defined score, if directly assigning a score is to arbitrary.
Not necessarily. A full argument would consider the opportunities available to a child you raise -- it's perfectly possible for a single first-world child to be a more productive than 180 kids in Africa.
There's also the counter-point (to my previous point) that having children discourages other people from having children, due to the forces of the market (greater demand for stuff available to children => greater costs of stuff available to children). Of course, the effect on demand is spread out to stuff other than just stuff available to children, so o...
Yep, he says so explicitly here: http://physics.stackexchange.com/questions/22578/can-black-holes-be-created-on-a-miniature-scale#comment52219_22601