Singer tends to avoid separating the human condition; instead, he focuses on critisizing the way people think. In fact, he doesn’t even use the term “people” or “persons” for humans who would consider people to be one with the human species. He claims that people are classified according to their behaviors and psychological capabilities. Chimpanzees are capable of doing many things that humans can, yet they are not regarded with as a human, or at least with the same respect as a human who cannot behave as one.

Singer declares that science classifies species by anatomy, and the sole purpose of this is not to seek truth. It is done to help people make sense of the disorganized mess that exists in the world. One would make an assumption, and then search for similarities in anatomy for proof of the hypothesis. These conclusions, then, do not reflect truth and reality; rather, they reflect the categorization of the scientist.