Briefly put, sustainability economics studies joint problems ofefficiencyandjustice. This is in contrast to, say, environmental andresource economics which traditionally focuses on problems ofefficiency, or environmental ethics which traditionally focuses onproblems of justice.The formulation given above of the basic question indicates thattheaimsof sustainability economics are twofold:1. Understanding. That is, sustainability economics has a cognitiveinterest.2. Management.Thatis,sustainabilityeconomicshasanactioninterest.While the aim of understanding makes sustainability economicsindeed a science, the latter—the interest to change and managehuman–environment systems in view of a vision of sustainability—clearly sets sustainability economics apart from the traditional idealof positive and value-free sciences. So, sustainability economics isneitherapurelypositivescience,norisitapurelynormativeendeav