This paper argues that any successful project in economics will need to adopt a philosophical orientation that is rather different to that of the current mathematical mainstream. In particular, it argues that explicit, systematic and sustained ontological analysis is required. The possibilities and limits of ontology are elaborated. The paper also sets out the explicit ontological conception that the author finds to be the most sustainable. He sees signs that such an orientation is being adopted in green economics and is optimistic that this development will continue. This paper defends crucial ideas that underlie and explain green economics.
Keywords: ontology, green economics, mainstream economics, economic modelling, modern economics problems