In Chapter 17 of The Omnivore's Dilemma, Pollan cites the book Animal Liberation by Singer. The argument Singer makes is that if one human being cannot use another simply because that human is more intelligent, then humans can not exploit animals simply because humans possess more intelligence. This is the premise of equality, and it requires us to treat animals so that we help them avoid pain, even if their interests are not the same as ours. This is what philosophers call "arguments from marginal cases." If we include infants or people with disabilities as people who deserve consideration, we should also include animals, the reasoning goes. Pollan says that we exclude animals from our consideration, we are guilty of what he calls "speciesism," which one day could be considered akin to racism.
Pollan also believes that the reason we can so brutally kill animals is that we are so removed from them. He believes that if we saw the industrial ways in which animals are killed today, we would eat a lot less of them and eat them with more respect.