A discussion on Humanism has broken out at Mere Comments, so I thought it might be useful to briefly describe my own ethical opinions.
My ethical opinions are best described as empathic libertarian humanism. There are certain experiences that I enjoy: joy, happiness, pleasure, and the like. There are other experiences that I do not enjoy: pain, grief, sorrow and the like. I wish to maximize the former and minimize the latter.
Because I am libertarian, I alone can construct what these experiences mean to me, and what objective circumstances cause these feelings; in general, each person constructs for herself what she considers happiness and suffering.
I am empathic in the sense that other people's happiness usually makes me happy, and other peoples suffering makes me suffer. My empathy is not, however, exact: I am indifferent, for instance, to the happiness of rapists, and I am indifferent to the suffering of the intolerant.
If some sort of experience causes me or others happiness, and doesn't cause me or others to suffer, then I will approve of that experience. Contrawise, if some sort of experience causes suffering and no happiness, I will disapprove.
Because my specific ethical opinions about what causes me happiness and suffering are indeed opinions and not matters of fact, there is no issue with having specific opinions about abstract experiences at varying levels of abstraction. For instance, although I'm straight man, and therefore gay sexual activities don't cause me any particular happiness, I have a positive opinion about the abstract notion of having rewarding consensual sexual experiences in general.
The big issue with this sort of humanist ethics is forming opinions about specific activities which cause some people happiness and others suffering. There are no rigorous, logical, objective answers to these sorts of issues: I must, rather, consult my feelings, discover how I feel about the various consequences and how I feel directly about the various actions available, and come to some conclusion.
Because I am a philosopher, I've examined my feelings in some detail. Although I've done some work in making my feelings consistent, on the whole my ethical beliefs are a matter of discovery rather than construction.