The article advances a framework allowing for a unified description of technical innova- tion and the advancement of theoretical knowledge. Cognitive structures based on fore- going actions with physical objects are externally represented by artifacts, language or writing. The exploration of actions with these external representations such as the fabri- cation and usage of new devices or the composition of texts opens up new possibilities for a reflective abstraction leading to new cognitive structures. The exploration of the options for actions is canalized by historically specific contexts constraining the actors. Based on the example of the early history of weighing with a focus on the establishment and differentiation of unequal-arm balances we elaborate the consequences of such an account
