This chapter explores the links between scientific systems approaches and adult cognitive development. First, it describes the premises and basic concepts of systems thinking. It then continues to give an overview of the history of systems approach and the development of the main models and theories from its roots, which lie in the natural sciences. This is followed by an examination of the three systems paradigms, namely, Closed Systems, Open Systems, and Dynamic Systems and their implications to research and operational interests, in addition to their explanatory power in today’s world. Second part of the chapter focuses on describing the intersections between the Dynamic Systems paradigm theories and Jan Sinnott’s theory of postformal thought. This is carried out by describing the key theories behind the paradigm, that is, self-organizing and self-referential systems and their applications to social systems. Furthermore, it examines Sinnott’s theory’s overlap with the third paradigm approach. The chapter concludes that there are some linkages between the fields. It suggests that both research fields could benefit from each other by gaining new understanding and insight, and a genuine merger could lead to new discoveries. The chapter is providing inspiration for future research by raising new questions, settings, and methodologies.