Singer argues that the interests of animals should be considered equally to those of humans, in cases where the two groups share a characteristic, such as the experience of suffering. However, in cases where two groups do not have the same characteristics, it would not always be useful to grant them the same rights. For example, it makes sense to grant the right to vote to both men and women, because both men and women have the same interest in being able to vote. But it would be pointless to grant the right to vote to chickens because chickens do not want to vote and would be intellectually incapable of doing so. In contrast, the
Universal Declaration of Human Rights provides that "Everyone has the right to life, liberty and security of person." It is a right that all men and women have an interest in enjoying, but one that chickens and all
sentient animals would also have an interest in enjoying. Consequently, according to the principle of equal consideration of interests, all sentient animals, human and non-human alike, should enjoy the right to life, liberty, and security. In the words of Jeremy Bentham, In doing so, Bentham emphasizes that the relevant criterion for granting the right to life and security is the capacity to suffer, not the capacity to reason or to speak. The capacity to suffer is sufficient to require protection from suffering. Singer explains this idea in
Animal Equality Explained to Humans: To determine the most moral course of action, Singer argues that one must consider "how much" one benefits from a situation, versus "how much" another suffers: "The essence of the principle of equal consideration of interests is to give equal weight in our moral reflections to the interests of all those affected by our actions. This means that if only X and Y are affected by an action, and X stands to lose more than Y stands to gain, then it is better not to perform the action." In the case of eating animal flesh, which is not essential for good health, the benefit to humans is only in temporary gustatory pleasure, while the cost to the animal is immense. ==Critiques==