The problems of weak sustainability and associated indicators

Sustainability is a grand challenge of our time. While there is a universal recognition that sustainability includes social, economic, and environmental components, the relationship and interchangeability between these components has been debated, resulting in three distinct sustainability perspectives: weak, strong, and absurdly strong sustainability. However, despite this active debate, few have questioned which types of sustainability commonly utilized index forms actually measure. Here we provide such an analysis, focusing on the interplay between the mathematical forms of sustainability indices and the three sustainability perspectives. We show that the computational underpinning of a sustainability index defines what type of sustainability the index is capable of measuring, while also providing alternative forms. We then provide a brief example of how these different sustainability perspectives can radically alter measured sustainability. We end with a call for sustainability researchers to be conscious of the values underlying index formation, deliberate in index selection, and explicit in result presentation, so that the scientific and stakeholder communities are better informed of sustainability assessments.