How do people born blind represent rainbows, or the color red, that they cannot perceive? How do we all represent abstract concepts, like freedom or justice?

People are capable of conceiving complex ideas and abstract concepts that do not have sensory referents, things to which these concepts point to in the world. The question of how such concepts are represented in the mind has been discussed by philosophers for centuries. In the 18^th century, rationalists and empiricists debated about the role of the senses in generating knowledge, and it...