A belief that markets are efficient is blamed for instigating the crisis we are in and lulling us into complacency as the crisis was approaching. But the debate about the role of such belief in the crisis is unfocused for two reasons. First, a lack of a common definition of market efficiency precludes a common language. Second, efficient markets are conflated with free markets.
The ambitious definition of efficient markets is their definition as rational markets, where security prices always equal intrinsic values. The modest definition of efficient markets is their definition as unbeatable markets. Bubbles cannot occur in rational markets but they can occur in unbeatable markets. I argue that a belief in market efficiency cannot bear responsibility for our crisis since most investors do not believe that markets are either rational or unbeatable.
Free markets are markets where government places little or no imprint on the financial behavior of individuals and organizations and on markets through regulations and direct intervention. Many advocates of free markets believe that such markets are also more efficient than markets which are not as free. But free markets are distinct from efficient markets. Highly regulated markets can be no less efficient in the sense of rational markets or unbeatable markets than lightly regulated markets. I argue that a belief that free markets are always superior to regulated markets and lightly regulated markets are always superior to heavily regulated markets does bear some responsibility for our crisis. Regulations that would have limited the types of mortgages offered to homeowners would have helped stem the crisis or mitigate it. So would have limits on the degree of leverage employed by banks and homeowners alike.
Yet not all regulations and government interventions bring unmitigated benefits. We have no precise measures by which we might distinguish real bubbles from illusory ones.Governments which aim to pop real bubbles run the risk of plunging us into recessions by popping illusory ones. The challenge we face is the challenge of seeing an opaque future as clearly as possible, knowing not only that foresight is not as clear as hindsight but also that we would be judged in the future as if it is.