Two dogmas of diagrammatic reasoning: A view from existential graphs

The vague notions of “visuality” and “iconicity” are not peculiar to diagrammatic reasoning autonomous from how average human beings happen to reason with logical diagrams. An equally problematic notion is involved in claims that take diagrams to be iconic representations, in the sense in which it is “iconicity” that would distinguish diagrams from whatever other, “non-iconic” notations and languages there may be. A diagram is an object either of perception or of imagination. As a material token, the diagram is a singular object and thereby determined in all respects. The purpose of a diagram is to represent certain relations in such a form that it can be transformed into another form representing other relations involved in those first represented and this transformation can be interpreted in a symbolic statement. Existential Graphs are for Charles Sanders Peirce diagrams that are “as iconic as possible”, and they are more iconic than, for instance, Entitative Graphs.