When public policies are designed from scratch, with no or limited possibility of learning from past experience, decision makers rely on their creativity and lateral thinking to counterbalance cognitive biases. One of the crucial issues for both evaluators and policy makers in such situations is not only to elaborate a sound theory of the programme but also to be aware of the existence of competing theories to solve the same problem. Being able to detect such theories constitutes an essential step to avoid ‘Type III errors’, that is, enacting the right solution for the ‘wrong’ problem. Reflecting on the analysis of two programmes aimed at preventing the death of children by heatstroke, this article illustrates the implications of alternative ‘accident theories’ for the evaluation of safety policies.

当公共政策是从头开始设计时，没有或从过去的经验中学习的可能性有限，决策者依靠他们的创造力和横向思维来平衡认知偏见。在这种情况下，评估者和政策制定者的关键问题之一不仅是详细阐述该计划的合理理论，而且还要意识到存在竞争理论来解决同一问题。能够检测到这些理论是避免“第三类错误”的重要步骤，即为“错误”问题制定正确的解决方案。反思旨在防止儿童中暑死亡的两个计划的分析，本文说明了替代“事故理论”对安全政策评估的影响。