Psychological terms are widely used to describe the biological world: plants, insects, bacteria colonies, even single cells are described as making decisions, anticipating rewards, and communicating with language. Carrie Figdor presents a comprehensive critical assessment of the interpretation of psychological terms across biological domains. She argues that we interpret these descriptions as literal claims about the capacities of such beings, and she argues against the anthropocentric attitude which takes human cognition as the standard for full-blooded capacities, to which nonhuman capacities are compared and found wanting. She offers an alternative view of what is required for a naturalistic explanation of the mind, and promotes finding a non-anthropocentric framework for determining distinctions in moral status. This is the first book to give a comprehensive theory of the interpretation of mental language throughout biology and to emphasize the role of mathematical modeling in the spread and revision of concepts.