ABSTRACT
The construction and the use of artifacts1-in particular complex artifacts-seems to be characteristic of human activities, but even more characteristic of human beings seems to be the possibility of the contribution of such artifacts beyond the practical level, e.g., their contribution at the cognitive level. In the fi eld of practice, tools have always played a crucial role; often practical problems are related to the use of an artifact, so that often the solution process of a given problem and the design of an artifact, expressly designed to support that solution, have been mutually developed. At best extent theoretical knowledge may be considered as originating from such a mutual shaping in a long-term process, the traces of which can sometimes be reconstructed.
