5. Violence produces violence.
Animal suffering is human suffering. Whether you kill animals yourself or pay others to do it for you, by creating an industry that requires humans to act violently, we contribute to a violent humanity. Individuals who work in slaughterhouses have some of the highest rates of workplace injury, mental illness, suicide, drug abuse and domestic violence. To quote William Blake, "a dog starved at his master's gate predicts the ruin of the state." Psychologists interpret violent behavior against animals as a precursor to violence against humans. The way we treat every living organism is a reflection of our entire worldview. We can't expect justice and peace within our own species while we terrorize others.
6. Animal agriculture affects us all.
According to the World Watch Institute: "[t]he human appetite for animal flesh is a driving force behind virtually every major category of environmental damage now threatening the human future - deforestation, erosion, fresh water scarcity, air and water pollution, climate change, biodiversity loss, social injustice, the destabilization of communities, and the spread of disease." Breeding, feeding and killing animals requires tremendous resources that are now being depleted beyond regeneration. This affects the world's poor most drastically. There are over 7 billion people on the planet, while nearly 1 billion people are currently malnourished or dying or starvation. More than 6 million children will die this year of starvation. 82 percent of these children live in countries where grain surpluses are fed to animals that are eaten by individuals in the developed world. One quarter of all of the grain produced in third world countries is given to livestock (Oppenlander, "The World Hunger-Food Choice Connection"). This affects food prices, food availability and food security for everyone.