ArgumentThe use of diagrams is pervasive in theoretical physics. Together with mathematical formulae and natural language, diagrams play a major role in theoretical modeling. They enrich the expressive power of physicists and help them to explore new theoretical ideas. Diagrams are not only heuristic or pedagogical tools, but they are also tools that enable developing the content of models into novel implications.

This paper investigates a the cognitive foundations of a pragmatic account of line drawings. It sets to highlight those features of line drawings that make them, as opposed to other types of visual representations, particularly conducive to communication. It is argued that representational and artifactual properties of drawings must be investigated together in order to understand the peculiarities of drawings as communicative tools.