How to define and interpret a probability in a risk and safety setting

This paper is a discussion paper and consists of two parts: first an introduction by the Associate Editor Genserik Reniers discussing the reason behind this article and classifying such a type of paper, and second the contribution by Terje Aven, with following abstract: The application of probability is of paramount importance for the risk and safety fields. But few of the papers in these fields explain what the probabilities introduced mean....