Easton's systems theory greatly contributed to the field of political science by providing a useful holistic framework, demonstrating how the political system functions, by meeting societal demands with policy outputs. Easton's interest lay in the political system's persistence, which in his model, merely required the existence of community. Communities, however, require state-provided security to survive in a hostile international environment. Hence, this paper builds a sub-systemic governance model able to explain domestic political system and state persistence. The model argues that large input generating groups require sufficient allocation of public goods for the long term maintenance of the domestic political system. Application of the model to the successful South Korean case demonstrated that the share of public goods increased along with the size of the input generating group. Long term disruption of this critical subsystem in countries with large input generating groups, however, can destabilize the state and its domestic political system with increased pressure from unmet societal demands. This new sub-systemic model seeks to advance understanding of the operation of the system and open up new areas of research into the persistence of the domestic political system. The systems approach has greatly contributed to the study of politics. David Easton's seminal Systems Theory drew attention to important aspects of political life and provided a critical framework with which to understand and analyze inputs into the political system and policy outputs to the social environment. The advancement of systems theory in political science was hobbled, however by methodological shortcomings. Easton failed to operationalize key concepts, and as a result, the theory was neither applied nor tested. In addition, Easton's all-inclusive system design was unable to give insight into several systems-related questions areas of interest to social scientists, including the survival or collapse of states and their domestic political systems, regime change, and variation in the nature of policy outputs or societal inputs. Combining Easton's policy process framework with methodologically rigorous approaches sharing key system's theory assumptions helps to deepen understanding of these issues. By narrowing Easton's system to a critical subsystem comprised of the leader and his/her supporters, it becomes evident that changes in the size of the input-generating group can markedly affect the quality of government policy outputs. This new sub systemic model yields the prediction that leader's seeking to maintain power will allocate an increased ratio of public goods to private goods, the larger the size of the input generating group. After operationalizing the size of the input-generating group and the share of public vs. private goods allocated through economic policy, this paper applies this sub systemic hypothesis to explain recent changes in economic policy making in South Korea. Modernization theory provides the added insight that the forces of industrialization and economic development are increasing the size of the input-generating group in societies throughout the world, which are calling for public policy goods, in the form of democratic political rights as well as improved overall living standards. Leadership failing to respond to these increased demands over a prolonged period not only provokes regime change, but, in certain circumstances, can destabilize and trigger the collapse of states and of domestic political systems. Research into underdeveloped institutions, economic power concentration, sectarian division and other factors impeding delivery of public goods to large input generating groups, can offer further insight into the question of systemic persistence, the central concern of Easton's systems theory. The article first critiques the strengths and weaknesses of Easton's systems theory. A sub-systemic model is offered to ameliorate the methodological shortcomings of Easton's systems theory while making it applicable to questions concerning the persistence of domestic political systems and state maintenance. Applied to two cases of Korean industrial restructuring, the predictions of the sub-systemic model hold true: small input generating groups under authoritarian rule were associated with provision of private goods, whereas larger input generating groups under democracy produced policies that allocated public goods. The final section of the paper then explores the possible collapse of the domestic political system in cases where leadership is unable to provide public goods to large input generating groups.
