Argument: That the retarded have rights does not justify animal rights
Carl Cohen. "Why animals have no rights. The Case for the Use of Animals in Biomedical Research" The New England Journal of Medicine 315, no. 14 (October 2,1986): 865-69 - "A common objection, which deserves a response, may be paraphrased as follows:
"If having rights requires being able to make moral claims, to grasp and apply moral laws, then many humans -- the brain-damaged, the comatose, the senile -- who plainly lack those capacities must be without rights. But that is absurd. This proves [the critic concludes] that rights do not depend on the presence of moral capacities."
This objection fails; it mistakenly treats an essential feature of humanity as though it were a screen for sorting humans. The capacity for moral judgment that distinguishes humans from animals is not a test to be administered to human beings one by one. Persons who are unable, because of some disability, to perform the full moral functions natural to human beings are certainly not for that reason ejected from the moral community. The issue is one of kind. Humans are of such a kind that they may be the subject of experiments only with their voluntary consent. The choices they make freely must be respected. Animals are of such a kind that it is impossible for them, in principle, to give or withhold voluntary consent or to make a moral choice. What humans retain when disabled, animals have never had. [p.866]"