Add to ORKGThe paper presents an extension of L. Nowak's idelization theory of science in order to explicate intuitions about unpredictability and contingency of history shared by professional historians and methodologists of history. In the first part of the paper, a critical analysis of some explications (G. Reisch, M. Shermer) of such intuitions, based on the conceptual apparatus of the chaos theory is presented. In the second part of the paper, an original model od cascade process is elaborated that conceptualizes the contingency of historical events. This model is subsequently compared with M. Shermer's model of historical sequences. In third part of this paper, the model of cascade process is applied in the construction of a scientific theory, ...