From Argument by Design to Nature Red in Tooth and Claw
Humans are great namers and classifiers of the natural world. Aristotle, however, was less sure that essences were so divine in nature. Aristotle’s system of classification in terms of animals’ essential characteristics begins with a kind of logical deduction called downward classification, in which more general attributes are higher in a hierarchy than more specific ones. The idea of ranking the natural world is a very old one. But after Aristotle, in later Greek and Roman times up to the Middle Ages, this method of ranking began to have a mystical, divine nature. The paradigm of natural theology had proposed special creation; Charles Darwin was a uniformitarian and believed in natural laws. Darwin’s speculations on the mental states of animals laid the groundwork for the field of comparative psychology or the study of the development and evolution of animal behavior.