My view [is] that what morality boils down to is, 'Don’t harm, and do help.' And now the question is, 'Can creatures like chickens and cows be harmed?' And the answer is, 'Of course they can.' Consequently, I think it’s immoral to harm them. And that seems to me to provide a very strong moral reason to be vegetarian, to not wear leather... it seems to me that our treatment of animals is morally appalling... and that we ought to radically revise the way we live, precisely because they feel pain, they can be hurt, and we’re constantly hurting these creatures!
~ Shelly Kagan