The bread-making machine: tacit knowledge and two types of action

We analyse Nonaka and Takeuchi's claim that a master baker's tacit knowledge was made explicit and incorporated into a home bread-making machine and its manual – the ‘knowledge capture’ thesis. In order to test the claim, bread was made without and with a breadmaker and we carried out an analysis of the bread-making actions before and after mechanization. Based on the theory of action morphicity it is shown that the machine only mimics the mechanical counterpart of just a few of certain special kinds of human bread-making actions. The remaining success of the machine and its manual is due to what other human actors bring to the mechanical bread-making scene; this way the breadmaker can be an adequate social prosthesis. Action mimicking, action substitution, and the contributions of these other human actors, who are not needed in the case of the master baker, explain why the machine and its manual do work. It is not a matter of the explication or incorporation of tacit knowledge, but of fitting a social prosthesis into a rearranged world.