‘All theory is gray … but forever green is the tree of life’

The title of this editorial is taken from a well-known quote by the German poet and philosopher J.W. Goethe (1749–1832). Goethe was partly lamenting the amount of time other scientists and thinkers spend on matters which largely theoretical, in contrast to those who gather data or use their intuition and experience to drive their work. Within the context of Policy and Practice in Health and Safety (PPHS) the quote might at first appear to have little relevance, however one of the aims of PPHS is to act as a forum for the discussion of scientific and practice-based aspects of occupational health and safety. Part of this involves theory and theoretical matters as these often crop up in discussions of the relevance of one rival theory of health and safety over another (e.g. comparisons between High Reliability Organization Theory and Resilience Engineering and their applicability to safety critical contexts – e.g. Haavik, Antonsen, Rosness, & Hale, 2019; Harvey, Waterson, & Dainty, 2019; Behavioural safety and its influence on safety culture – e.g. Marsh, 2017). One of the key roles of theory is to generate predictions and to arrive at something (e.g. an intervention) which can be tested and verified. Without a sound and detailed theory (or a set of theories) research runs the risk of delivering only anecdotal evidence which in turn, is difficult to translate into practice. As Andrew Hale (2014) puts it: