In marketplaces, reputation is based on observable qualities, such as evidence of customer satisfaction, that signal trustworthiness. Reputation systems can be conceptualized as abstract social systems in which trust emerges through structured observation and communication. However, existing research on reputation systems is predominantly technical and often neglects the integration of social and technical incentive mechanisms. To address this gap, this study adopts a systems-theoretical perspective to conceptualize blockchain-based business reputation systems at a unified level of abstraction. Drawing on key concepts from social systems theory—observation, selection, communication, system trust, and elements and relations—we propose a design lens that aligns social and technical design layers. This study contributes to design science research in information systems by demonstrating how systems thinking can provide foundational conceptual scaffolding for the design of reputation system artifacts.