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For three centuries, economists and bankers have disagreed about the most basic facts of banking: whether banks create money or merely intermediate it, whether their lending is self-regulating or crisis-prone, and whether the system needs radical structural reform or only better supervision. These disagreements are not abstract curiosities. They have shaped central bank charters, deposit insurance schemes, capital requirements, and the design of financial regulation. The eight frameworks that follow represent the most influential attempts to answer those questions, each one emerging in response to a crisis, a theoretical puzzle, or a perceived failure in its predecessors.
The first systematic framework for understanding banking was the Real Bills Doctrine, which dominated British and American monetary thinking from the early eighteenth century until the Great Depression. Its core claim was simple: if a bank issued notes only to finance short-term, self-liquidating commercial transactions—a merchant's bill of exchange that would be repaid when the goods were sold—then the money supply would automatically expand and contract with the needs of trade. Over-issuance was impossible because no prudent banker would lend against speculative or long-term assets. The doctrine provided the intellectual justification for the real-bills clause in the original 1913 Federal Reserve Act, which required the Fed's discount window to accept only short-term commercial paper. The flaw, which became devastatingly clear during the 1920s and 1930s, was that a collection of individually sound loans could still fuel an aggregate credit boom. The real-bills criterion could not distinguish between a healthy expansion of trade and a speculative bubble, and it offered no guidance during a panic when the demand for liquidity surged precisely when trade was collapsing.
The Currency School and the Banking School emerged in the 1830s and 1840s as direct antagonists in a live policy dispute over the Bank of England's note-issuing powers. The Currency School, led by Samuel Jones Loyd, Robert Torrens, and George Warde Norman, argued that the note issue should be strictly tied to the Bank's gold reserves. They proposed a monopoly on note issuance by a separate Issue Department of the Bank of England, which would follow a mechanical rule: notes could be issued only against gold or government securities, not against commercial bills. The Banking School, whose leading figures included Thomas Tooke and John Fullarton, rejected this proposal outright. They argued that the volume of notes in circulation was determined by the needs of trade, not by the Bank's reserve policy. An attempt to restrict the note supply, they claimed, would simply drive up interest rates and choke off legitimate commerce without preventing speculative excesses. The Banking School's insight—that credit creation is endogenous to the economy and cannot be controlled by a simple reserve rule—was a direct challenge to the Currency School's mechanistic view. The Currency School won the legislative battle: the Bank Charter Act of 1844 implemented their proposal, separating the Bank into Issue and Banking Departments and capping fiduciary note issuance. But the Banking School's critique never disappeared; it resurfaced more than a century later in a very different form.
By the 1930s, the Money-Multiplier View of Banking had become the textbook orthodoxy. In this framework, the central bank controls the supply of reserves, and banks lend out a multiple of those reserves, constrained by reserve requirements and the public's demand for currency. The causal chain runs from reserves to deposits: the central bank injects reserves, banks create loans and deposits up to the multiplier limit, and the money supply is therefore exogenously determined by the monetary authority. This view dominated macroeconomic textbooks for decades and still appears in many introductory economics courses. Its appeal was clarity: it gave central bankers a simple lever (reserves) to control the money supply. But it also carried a strong implication that banks are passive intermediaries that merely multiply the reserves the central bank provides.
The Narrow Banking framework, first proposed in the 1933 Chicago Plan by economists including Henry Simons and Irving Fisher, took the Money-Multiplier View's logic to its radical conclusion. If banks create money by lending against fractional reserves, and if that process is inherently fragile because depositors can run, then the solution is to require banks to hold 100% reserves against demand deposits. Narrow banks would be pure custodians of transaction accounts, unable to lend depositors' money. Lending would be done by separate investment entities funded by equity or long-term debt. The Chicago Plan was seriously debated during the New Deal but never enacted; it faced fierce opposition from the banking industry and was sidelined by the introduction of federal deposit insurance in 1934, which addressed the run problem without restructuring the banking system. Narrow Banking has never been implemented at scale, but it remains a recurring reference point in debates about financial stability, especially after the 2008 crisis revived interest in limited-purpose banking.
The Post-Keynesian Endogenous Money framework, developed from the 1960s onward by economists such as Nicholas Kaldor, Basil Moore, and later Randall Wray, directly revived the Banking School's causal claim about credit-driven money creation. In this view, the Money-Multiplier View gets the causation backwards. Banks do not wait for reserves before lending; they make loans first, creating deposits in the process, and then seek reserves from the central bank to meet settlement requirements. Because modern central banks operate with an interest-rate target, they supply whatever reserves the banking system demands at the target rate. The money supply is therefore endogenous—determined by the demand for bank credit, not by a reserve multiplier. The Bank of England's 2014 quarterly bulletin, which stated that "in the modern economy, money is created by commercial banks making loans," was widely cited as official confirmation of the endogenous-money view. This framework coexists in tension with the Money-Multiplier View: the multiplier remains a useful approximation in some textbook contexts, but the causal mechanism it describes no longer matches how central banks actually operate.
The frameworks discussed so far focused on the macroeconomics of money and credit. A different set of questions emerged in the late 1970s and 1980s: Why do banks exist as a distinct type of financial institution? And why are they so vulnerable to runs? The Asymmetric-Information Theory of Banking, launched by George Akerlof's 1970 "lemons" paper and applied to banking by Joseph Stiglitz, Andrew Weiss, and others in the late 1970s, answered the first question. Banks exist because they solve a problem that securities markets cannot: they screen and monitor borrowers whose creditworthiness is hard for dispersed investors to assess. A bank's comparative advantage lies in its ability to gather private information about borrowers, to monitor their behavior over the life of a loan, and to use long-term relationships to reduce moral hazard. This framework explained why bank lending is relationship-intensive, why banks hold illiquid loans funded by liquid deposits, and why disintermediation—the shift from bank loans to market securities—has limits. It also implied that banks are inherently opaque, because their loan portfolios are hard for outsiders to value.
The Bank Fragility and Liquidity Insurance Theory, most famously formalized by Douglas Diamond and Philip Dybvig in their 1983 model, took the next step. If banks exist because they transform illiquid loans into liquid deposits, then they are vulnerable to self-fulfilling runs. In the Diamond-Dybvig model, depositors' expectations determine whether a run occurs: if everyone believes others will withdraw, the rational response is to withdraw early, and the bank fails even if its assets are fundamentally sound. Deposit insurance can eliminate the run equilibrium, but it introduces moral hazard because insured depositors have no incentive to discipline bank risk-taking. This framework directly complements the Asymmetric-Information Theory: the same features that make banks valuable—maturity transformation, information-intensive lending—also make them fragile. The two frameworks agree that banks are special and need regulation, but they differ subtly on the primary source of fragility. The Asymmetric-Information Theory emphasizes that banks are fragile because their assets are hard to value in a crisis; the Liquidity Insurance Theory emphasizes that fragility is built into the deposit contract itself, independent of asset quality. Both frameworks remain central to modern banking regulation, informing the design of deposit insurance, liquidity requirements, and stress testing.
Today, no single framework commands universal assent. The Asymmetric-Information Theory and the Bank Fragility and Liquidity Insurance Theory together form the microfoundational core of academic banking theory. They are the frameworks most often cited in regulatory debates, and they underpin the Basel III liquidity coverage ratio and the net stable funding ratio. The Post-Keynesian Endogenous Money framework has gained ground among central bank practitioners, especially after the Bank of England's 2014 bulletin, but it remains a minority view in mainstream macroeconomics, where the Money-Multiplier View still appears in many textbooks despite being descriptively inaccurate for most modern economies. The Narrow Banking framework is a persistent minority voice in policy debates, resurgent after every major banking crisis but never adopted. The Real Bills Doctrine, the Currency School, and the Banking School are of mainly historical interest, though the Banking School's endogenous-money insight lives on in its Post-Keynesian descendant.
The leading frameworks agree on several points: banks are not neutral intermediaries; their lending decisions affect the money supply and the real economy; and their fragility justifies some form of public safety net. The main disagreements are about the direction of causality (do reserves drive lending or does lending drive reserves?), the optimal design of the safety net (deposit insurance versus narrow banking versus macroprudential regulation), and the extent to which fragility is an inherent feature of banking or a consequence of poor regulation. These disagreements are not merely academic. They shape how central banks conduct monetary policy, how regulators set capital and liquidity requirements, and how policymakers respond to the next crisis.