Peirce, Muybridge, and the Moving Pictures of Thought

Peirce once called his graphical system of logic-the Existential Graphs-the moving pictures of thought. I argue that Peirce meant that using his graphs to study the movement of thought is akin to Eadweard Muybridge's use of moving pictures to study animal motion, and I show that this analogy is highly apt for several reasons. The analogy is apt because: (1) Just as animal motion is continuous, thought is continuous; (2) Animal motion, like the movement of thought, is too swift and complex to examine directly, without aid; (3) Nevertheless, just as we can record a series of moments of animal motion with the use of a special instrument (viz., cameras and instantaneous photographs), so too we can record a series of moments of thought with the use of a special instrument (viz., the Existential Graphs), enabling us to study its structure; and (4) Through the study of these moments of thought, or of animal motion, we will improve our understanding of them and be able to settle debates about them.