Homo sapiens has a tendency to assume itself to be overwhelmingly superior to all other species, having the right to kill, mutilate and enslave the others at will. Speciesism has been defined as the high barrier placed by man between the human species and all the rest of the animal species.
Speciesism is analogous to sexism or racism. It is a distinction made between individuals that is arbitrary and indefensible. It is fallacious to argue that faculties such as reason and language create a higher moral plane on which man relates to man when such rights are extended in practice to the morally innocent such as babies or the mentally handicapped. Just as such people are not denied the rights to moral treatment by their condition, the same should apply to animals. Furthermore, what is known of human suffering is also true of animal suffering, with the added moral imperative that animals are unable to defend themselves.
More than five decades of fundamental discoveries on the brain and behavioural evidence for consciousness has shown no difference so far between humans and other mammals. Species differences such as the size of neocortex appear to be irrelevant to waking and perceptual consciousness. The burden of proof for the absence of subjectivity in mammals should therefore be placed on the skeptics.
Most humans are speciesist. They assume it is acceptable to discriminate against non-human animals merely because they belong to a different species. Speciesism is a prejudice akin to racism and sexism. Those prejudices involve discrimination by a dominant group against a weaker one based on morally arbitrary characteristics.
We should adopt a moral principle of equal consideration of interests, that applies regardless of species. If it is wrong to cause a human being to suffer, it should be equally wrong to cause a nonhuman animal to suffer to a similar extent.
The key ethical question about animals is not “can they reason?” nor “can they talk?”, but “can they suffer?” (Jeremy Bentham)