The authors discuss Popper's and Kuhn's theories of science and consider whether these can explain the real course taken by the history of science, that is the real behaviour of scientists seen in an historical light. It has mainly to do with the problem of what criteria influence scientists in deciding on the acceptance of one of several possible theories. The authors postulate the necessity of introducing the category of "objective technological Erkenntnisinteresse" to help solve the problem. They illustrate this (...) by analysing the various models of the structure of Benzol, proposed by Kekulé, Claus and Ladenburg. According to the authors, Popper and Kuhn cannot explain the fact that the model of Kekulé was readily accepted. It can however be explained with the category of Erkenntnisinteresse. (shrink)