Crossing the river by feeling the stones

To pursue a scientific enquiry is often to bring a diversity of phenomena into new concepts. To follow the traditional scientific route means then translating everything into abstractions in mathematical function relationships or statistical correlations. Maybe sustainability, instead of only being an abstraction, should also offer concrete versions of the reality it represents. Industrial Ecology has been called the science of sustainability. In this context it is worth considering which kind of research it should focus on: ¿objective¿ engineering including metabolic modelling, and/or including also more normative ideas and the relationship between Industrial Ecology and sustainability in practical action programs. Industrial Ecology has been developed as a field where quantitative methods were applied to industrial and urban metabolism. The concept of sustainable development was latterly incorporated into this field: a concept that also includes values. We could argue the work of a researcher in industrial ecology is to strive to sort out what is science and what is merely based on values and cooperate closely with actors in society to create images of a more sustainable future