Reconciling “weak” and “strong” sustainability

A conceptual and analytical approach is presented to reconcile weak and strong sustainability. It involves a reconsideration of the conception of total capital from an ecological‐economic system perspective. In particular, natural capital is classified into non‐renewable resources, renewable resources that are harvested, and those that are not used in production. Strong sustainability is defined in terms of constant environmental quality. Weak sustainability is characterised by non‐decreasing value of aggregate income and environmental quality, and formalised in terms of a “preference‐based social value function”. Ecosystem resilience and basic human needs are introduced as minimum sustainability requirements, and a “sustainability‐based social value function” is proposed, which is sensitive to potentially irreversible changes at the boundaries of the restricted opportunity space. It implies higher values associated to the trade‐offs between income and the environment than the preference‐based function, and the fact that sustainable development is only feasible if both minimum criteria are fulfilled.