Three experiments: The exploration of unknown unknowns in foresight

•Complexity increases uncertainty of decision making.•Decision making can be supported even for un-probable futures.•In order to address deep uncertainty, we have to relax the plausibility requirements.

Emerging uncertainties present a challenge to decision making. On the basis of a review of existing scenario methods, we examine how ontological uncertainty, that is, the situation in which we do not know what we do not know, is included in scenario processes. We present three experimental foresight methods applicable for cases dominated by uncertainty; structural scenarios, shock scenarios and action portfolio and Agent-Based Modeling. The main finding of our experiment is that in order to address uncertainty, we have to relax the plausibility requirements and focus the analysis on futures that are perceived to be non-probable. In this way we are able to challenge existing perceptions and multiply the number of mental models of the futures.