Mainstream economists give the misleading impression that their argument for austerity is purely technical and indeed the most ‘scientific’. The argument developed here is that their reasoning is not, any more than that of their heterodox critics, independent of ideology, power and ethics. The widespread belief in austerity policies as scientifically justified has prevented arguments against austerity gaining more traction; issues of ideology, power and ethics need to be brought to the fore as part of the arguments on both sides. In other words, awareness of the epistemological issues arising from an open-system ontology is critical to understanding the crisis and the policy response, and therefore to challenging that understanding and encouraging a radical policy shift. The critique of austerity policies would therefore be strengthened by a critique of the mainstream’s rhetorical (mis)representation of economic theorising.