3. Complexity in sustainability assessment

Complexity in sustainability assessment

Sustainability issues are often characterised by a high degree of complexity. We’ll follow a convenient presentation of complexity as being of double order: complexity of the elements of nature (ecosystems), and complexity of human systems.

Ecosystems are characterised by a diversity of different elements with multiple and interlinked energy and material flows. Our knowledge regarding the mechanisms involved in those relations and the properties of their elements is limited to their high complexity.

Human social systems are also very complex, characterised by a high number and diversity of elements and multiple and unpredictable interactions and behavior patterns. Social science has just started to explore the mechanisms explaining interaction in and structuration of human societies.

Sustainability issues, lying in the interface between ecological and human systems have therefore a double order of complexity. It is obvious that the higher the complexity of any given system is, the higher number of valid perspectives there may be regarding it.

Dealing with this double order complexity requires, as a minimum, a pluri-disciplinary standpoint, which can be dealt through the collaboration of scientists from different fields: social sciences, ecology and biology, economics, etc. But interdisciplinary collaboration may not be enough, as complexity science and post-normal science agree on identifying the plurality of valuation languages and perspectives as an important element to be taken into account in sustainability assessment. This issue is further developed in related grains.