Uncertainty about the uncertainty in seismic hazard analysis

In recent years, practitioners of probabilistic seismic hazard analysis have adopted the use of the terms aleatory and epistemic uncertainty. This new terminology has been criticised as a new weapon in the probabilistʹs arsenal, whereas, in fact, nothing has actually changed: These are merely new words for the existing concepts of randomness and uncertainty, whose usage has become confused and ambiguous. The debate regarding the relative merits and shortcomings of deterministic and probabilistic approaches will no doubt continue for many years. However, this debate could become more productive if clear definitions of concepts, such as uncertainty, are first established to avoid discussions at cross purposes.