ABSTRACT
Everybody prides themselves on being rational, in the sense that there are reasons for what they do. This is at least so in relation to work, except for the work of artists. The ideal of rational behaviour is that there is a reason for what we do that it is based on an understanding of a situation and a consideration of the pros and cons of a specific choice, at least in cases where decisions are made. When thinking about safety, there must necessarily be a symmetry between the past and the future, which means that future accidents must happen in the same way as past accidents. Or, to put it differently, the reasons why accidents happened in the past must be the same as the reasons why accidents will happen in the future. The Swiss cheese model represents events in terms of composite linear causality, where adverse outcomes are due to combinations of active failures and latent conditions (hazards).
