The paper aspires to provide a logical examination of the main current praxiological paradigm or ideology, called capitalism, vs the desired and, as it seems, without alternative new praxiological paradigm known as sustainabilism, or sustainability model of rationality. To this end, firstly the concept of sustainability is clarified, then the capitalist model of rationality is deciphered and evaluated, based on three structural components: values, principles, and outcomes. Thirdly, this model of rationality is critically examined and, as a result, some undesirable effects of all three structural components are highlighted. Based on this examination, new values, new principles, and new outcomes are proposed and justified, so getting the sustainability model of rationality or sustainability ideology, whose name is proposed to be communitarianist model of rationality, or simply, communitarianism (instead of the current capitalism). The analysis is based on the logical approach and has an abstract and general character, although the economic component of the societal system often stands out as meaning and role.