Peter Singer looks at the issue of equality, beginning with the argument that biologically speaking, all humans are not created equal. He describes studies which have shown more or less consistently, that humans have varying levels of intelligence. For the sake of argument Singer entertains this idea as truth. Singer argues, that even under the assumption that humans are not biologically equal, they still have the right to be treated equally.
To Singer, this idea of ethics is a form of utilitarianism, with the exception that his idea is based on interests and the best interests of all individuals involved as opposed to Bentham and Mill's simple idea of pleasure and pain. Singer looks at utilitarianism as a most fundamental framework for ethics, a foundation for more specific and complex ideas to come. He argues that in order to fully understand ethics, utilitarianism is a crucial first step. From this, Singer arrives at the premise that "the fundamental principle of equality, on which the equality of all human beings rests, is the principle of equal consideration of interests" (55).
This idea, that ethics revolves around interests and the equal significance of them, leads Singer to argue that it should also apply to animals. He argues that the same logic that dictates the equal consideration of interests among humans also dictates the same consideration for animals of all species. By this logic, he equates racism to what he terms "speciesism". The former seeks only the best interest of their own race, the latter seeks only the best interest of their own species. If we are to say that all humans should be considered equal regardless of intelligence, we must also say that all animals should be considered equal as well. An interesting quote from Bentham says that "the question is not, can they reason? Nor can they talk? But, can they suffer?" (57). In other words, what should entitle a being to equal treatment is not how intelligent it is, but whether or not it can experience pain or pleasure.
This idea of Bentham's is a foundational principle for David Lane's neuro-ethical argument. Lane argues that regardless of how intelligent they are or not, animals nonetheless have a central nervous system that allows them to experience pain or pleasure, as he states “If it is true that those species with central nervous systems are much more likely to feel pain…then it would seem easy and wise to me that we should try to avoid eating them”. This, by Lane’s logic and that of Bentham makes it just as unethical to eat an animal is it is to eat another human being. Lane’s neuro-ethical argument has more in common with the original form of utilitarianism than it does with Singer’s variant.