Since ancient times, philosophers have maintained that to strive too hard for one's own happiness is self-defeating. - Peter Singer

Becoming a vegetarian is not merely a symbolic gesture. Nor is it an attempt to isolate oneself from the ugly realities of the world, to keep oneself pure and so without responsibility for the cruelty and carnage all around. Becoming a vegetarian is a highly practical and effective step one can take toward ending both the killing of nonhuman animals and the infliction of suffering upon them.

Science does not stand still, and neither does philosophy, although the latter has a tendency to walk in circles.

The goal of maximizing the welfare of all may be better achieved by an ethic that accepts our inclinations and harnesses them so that, taken as a whole, the system works to everyone's advantage.