Safety activities may provide assurance of safety even where such assurance is unwarranted. This phenomenon – which we will call “probative blindness” – is evident both in hindsight analysis of accidents and in the daily practice of safety work. The purpose of this paper is to describe the phenomenon of probative blindness. We achieve this by distinguishing probative blindness from other phenomena, identifying historical instances of probative blindness, and discussing characteristics and causes associated with these instances. The end product is an explanation of the features of probative blindness suitable for investigating the probative value of current safety activities, and ultimately for reducing the occurrence of probative blindness