The Fiat–Credit Allocation Theorem: A Law of Motion for the Post-Bretton Woods Economy

This paper introduces the Fiat-Credit Allocation Theorem (FCAT), developed by Aaron Black. Since the collapse of Bretton Woods in the early 1970s, advanced economies have operated under a distinct monetary and financial regime characterized by pure fiat currencies, elastic bank credit creation, and widespread securitization of cash flows. The Fiat–Credit Allocation Theorem (FCAT) is a structural law governing credit allocation in this post-1971 era. In a fiat system with low-friction securitization, credit endogenously expands into securitizable assets whenever their perceived risk-adjusted expected returns exceed the system-wide required return on risky capital (r ˉ), and contracts when returns fall below this hurdle rate. In equilibrium, risk-adjusted returns on funded securitized cash flows converge to r ˉ, creating a yield-arbitrage mechanism that drives sustained asset-price inflation, financialization, rentier dominance, and recurrent credit-driven booms and busts. The theorem formalizes this process in a minimal continuous-time framework, proves convergence under mild assumptions, and interprets key post-Bretton Woods phenomena—decoupled capital returns from wage growth, persistent r>gdynamics, and leverage cycles—as equilibrium outcomes rather than anomalies. Empirical proxies, including yield convergence across securitized asset classes post-1971, support the model's predictions. FCAT provides a unified micro-founded explanation for the regime shift from production-constrained credit to yield-chasing credit, with implications for inequality, affordability in essential sectors, and the limits of supply-side reforms.