Final answer:
Speciesism is the belief that one species is superior to others, which leads to the mistreatment of animals. Dr. Singer argues that if we accept animal experimentation, we should also accept experimentation on severely mentally disabled humans.
Step-by-step explanation:
Speciesism is the belief that one species is inherently superior to others and therefore has the right to exploit and mistreat other species. Dr. Singer uses this term to explain why we abuse animals, arguing that our tendency to prioritize human interests and value humans more than animals leads to the mistreatment of animals. He also uses the argument that if we accept the use of experimentation on animals, then we should also accept experimentation on severely mentally disabled humans to challenge the ethical basis for using animals in research.