Cobweb Theory, Market Stability, and Price Expectations

Contributors to cobweb theory include many leading economists of the twentieth century. From early beginnings in 1930, cobweb theory played a key role in evolving perceptions of market stability arising from recursive linear models with endogenous dynamics. The focal point of this evolution in cobweb theory is the transition from naive to adaptive to rational price expectations. After a review of the prehistory, this paper examines the first wave of linear cobweb theory initiated by Jan Tinbergen, Henry Schultz, and Umberto Ricci and proceeds to consider the evolution of price expectations in the second wave of cobweb models associated with endogenous cycles in commodity markets. The role of modern cobweb theory in discussions about the stability of market equilibrium and the connection to processes with rational expectations is assessed.