The reaper and the scanner: indivisibility-led incremental innovations and the adoption of new technologies

Widespread adoption of a new capital-embodied technology requires a continuous flow of incremental innovations. A few of them address the key problem of indivisibility, by making renting the new machine a viable alternative to buying it, or by dividing it up into modular elements. Such incremental innovations differ from the learning-by-doing effects usually considered by diffusion models, and greatly affect the structure of the adopting industry. The case for keeping them in due account is made by revisiting Paul David’s classic paper on the McCormick reaper, by criticising the subsequent evolution of threshold models of adoption, and by summarising my own findings on the diffusion of electronic pre-press devices