This Element brings together the problems of economic calculation, institutional diversity, and institutional feasibility, arguing that these themes are deeply interconnected and mutually reinforcing. Building on recent developments in institutional theory, political economy, social philosophy, and logical analysis, the Element revisits the classic debates surrounding alternative economic and governance systems. The discussion is organized around three core elements: (1) an overview of recent developments in institutional theory and social philosophy, that driven by technological advances have revitalized debates on alternative economic and governance systems; (2) a reexamination of the economic calculation debate, tracing its evolution from Austrian economics to a broader theoretical synthesis incorporating institutional political economy and conflict theory; and (3) a discussion of the formal, logical, and philosophical foundations for thinking about feasibility and realizability, offering analytical tools for evaluating the plausibility of institutional alternatives within specific historical and social contexts.