KEYNES, KEYNESIANS AND THE EVIDENCE ON U.K. TRADE CYCLES

Many scholars have noted that, since at least 1790, U.K. economic fluctuations have seemed to reach major peaks every 7–10 years. Keynes (1936, ch.18) used the elements of his theory to explain non‐periodic economic fluctuations. His explanation of periodic fluctuations, i.e. cycles, appears in Chapter 22 of the General Theory. As is well known, he believed that fluctuations in “animal spirits” (that were often only loosely connected with the cost and the real rate of return on capital) led to oscillations in investment which, combined with the durability of capital goods, caused the duration of modern major cycles; fluctuations in liquidity preference and the propensity to consume played lesser roles. Bowing to Jevons (1964), Keynes also noted that unstable agricultural inventories could have been a source of waves in the early 19th Century when agriculture was relatively more important in the U.K. But Keynes did not demonstrate just how his investment theory implied a definite cycle period, because he did not merge his multiplier with the accelerator principle to provide an endogenous explanation of periodic turning points in output. Consequently, as Hicks (1950, p. l) notes, Keynes did not demonstrate how investment and income could peak every 7–10 years; his was really a theory of nonperiodic waves.