James Rachels on vegetarianism:

Vegetarianism is often regarded as an eccentric moral view, and it is assumed that a vegetarian must subscribe to principles at odds with common sense. But if this reasoning is sound, the opposite is true: the rule against causing unnecessary pain is the least eccentric of all moral principles, and that rule leads straight to the conclusion that we should abandon the business of meat production and adopt alternative diets. Considered in this light, vegetarianism might be thought of as a severely conservative moral stance. (Created from Animals, p. 212)

Stephen R. L. Clark makes a similar point in his book The Moral Status of Animals: one needn’t adopt a radically revisionist moral stance to see that current methods of meat production impose vast amounts of unnecessary suffering. And “do not be the cause of avoidable suffering” is about the most platitudinous moral platitude around.