Random and epistemic uncertainties, how to distinguish and manipulate them in reliability studies?

Summary In the literature, different methods of classi- fication of uncertainties and their sources are proposed. The most common distinction being to divide uncertainties into two types: random uncertainty and epistemic uncertainty. The first being irreducible and due to the natural variability of random phenomena. The second is due to a lack of knowledge that can be reduced by making more efforts (data collection, expert consultation, accelerated testing, etc.). In this paper, we will propose a discussion of the validity of this distinction and show that it has implications for the choice of theory to be used to represent the different types of uncertainties.