The double negative approach to sustainability

Thirty years after Bruntland there is still no consensus on how sustainability should be defined. This is due to the multiplicity of value laden meanings, tradeoffs between goals, the political aspects of goal prioritization and the variance over time and place in perceptions of challenges. In the recent two decades, a double negative approach has gradually been accepted. That is, rather than defining what sustainability is, the emphasis has shifted to definitions of what is unsustainable, thereby identifying safe and just spaces, which can be viewed as sustainable states. In this paper, we review the evolution of the double negative approach, arguing that it can be generalized. We show this approach is scalable and adaptable, as it allows for the introduction of additional dimensions as a function of scale, sector and setting. To operationalize this approach we propose a method to identify red lines that serve as benchmarks for safe and just spaces.