The excellent Unlearning Economics site raises the question of the need for a new unifying principle for economics. My two pennyworth:
Economics, the ordering of our living space, should be founded on ecology, the study of our living space, because we cannot order a thing without understanding it.
This insight has a massive impact on economics, because it brings with it three axioms: it is impossible to expand forever into a finite space, it is impossible to take forever from a finite resource, and everything in the biosphere tends to be interrelated. These axioms in turn have a revolutionary impact on economics, not least by blowing the economics of growth out of the water. The steady state economy becomes the destination. Work becomes re-evaluated in terms of its ability to restore order into our world http://www.greenhealth.org.uk/PhilosWork.htm. The overarching need to stabilise our being-in-the-world transcends the anthropocentric quarrel as to whether the collective or the individual should have primacy.
Ecology has a lot going for it as a principle that can unify economics.