ABSTRACT
This chapter argues that Charles Sanders Peirce’s semiotics is exactly the form of Kantism, as it inherits and reformulates Kant’s schematism and that a Peircean sign is precisely akin to Kantian schema, that is, to that element capable of keeping together aesthetic and logic, intuition. The diagram embodies prototypically that operational feature that is the epistemologically crucial property of the icon. According to Peirce, to experiment on a diagram is to make virtual properties not immediately perceivable in its object, but nevertheless present, emerge. Diagram is a sign that displays features that remain only virtual in the object before the intervention of the sign and that only the sign is able to manifest. An icon is always a perceptibly observable sign, and even the most abstract logical procedures ground their heuristic effectiveness in the ability to manipulate a diagram in the imagination.
