Abstract

The paper tracks the major changes Peirce brought to the classifications of signs in the Harvard Lectures on Pragmaticism, and the Lowell Lectures, both of 1903. These changes turn on the discovery of the need to include in the theory of signs an account of the thinghood and the eventhood of signs. This discovery becomes the “First Trichotomy” of the classification into three trichotomies and ten classes. It investigates the significance of these changes, both for the scope of sign theory, and for the function sign theory has to play in the mature pragmatism.