Economies don’t grow in a straight line. They lurch: credit expands, asset prices climb, then the same debt that funded the climb forces a contraction.
Modern economic commentary tends to treat each downturn as a surprise, a shock arriving from outside an otherwise stable system: a pandemic, a bank failure, a bad harvest. Yet the pattern itself, expansion followed by contraction, recurs across centuries and across very different monetary regimes, which suggests the cycle is not purely accidental. What causes it, however, is genuinely contested rather than settled.
At least three traditions offer different accounts. Austrian business cycle theory blames credit expansion, usually driven by central banks holding interest rates below their “natural” level, for distorting investment decisions until the distortion has to unwind. Real business cycle theory instead treats booms and busts as the economy’s normal response to external shocks (technology, productivity, resource supply) working through otherwise efficient markets. Hyman Minsky’s financial instability hypothesis locates the cause inside the financial system itself: economic stability, Minsky argued, is destabilising, because a calm stretch of growth encourages borrowers and lenders to take on progressively more fragile debt until the system can no longer absorb a shock.
Minsky’s account is the one most directly relevant to a debt-based monetary system specifically. He described three financing postures firms and households cycle through: hedge finance, where income comfortably covers both principal and interest; speculative finance, where income covers interest but principal has to be rolled over into new debt; and Ponzi finance, where even the interest requires fresh borrowing to cover. As a credit expansion continues, the mix shifts from hedge toward speculative and Ponzi financing, because success breeds confidence and confidence breeds leverage. This maps onto a structural mismatch at the heart of interest-based money creation: debt and the interest owed on it compound continuously, while the real output available to service that debt grows more slowly and unevenly. Eventually the gap between what is owed and what can actually be earned to repay it becomes unsustainable, and the same borrowing that produced the boom forces the deleveraging that produces the bust.
Source: Minsky, H.P., “The Financial Instability Hypothesis,” Working Paper No. 74, Levy Economics Institute of Bard College, 1992.