Concepts, therefore, have six main characteristics: (1) they allow us to discriminate the entities to which they apply with some reliability, (2) they entail a certain amount of knowledge regarding the semantic content of the term in question, (3) they vary across individuals, cultures, and moments in time, (4) they allow us to make inferences, (5) they are not linked to concrete sensory stimuli, and (6) they don’t generate a fixed behavioral response. If an animal doesn’t display these characteristics in her abilities and behavior, it means she lacks concepts.
