 Roemer has continued to work on issues of socialist design, focussing more recently on the modelling of individual economic behaviour (Roemer 2019a). Any coherent socio-economic system, he suggests, requires “three pillars”: a set of property relations and institutions that organise the allocation of resources; a distributive ethic that identifies a fair or just pattern of income and resources; and a behavioural ethos that specifies how economic actors make decisions. These three should work together, in that if economic agents act according to the relevant ethos, then the relevant institutional arrangements should implement the relevant just distribution. Roemer now insists that the behavioural ethos is as important as the other two pillars, and criticises earlier models of market socialism—including coupon socialism—for having changed the institutional arrangements of capitalism but kept its behavioural ethos (Roemer 2019a: 179; see Carens 1981 for a possible exception).