Senators John McCain and Maria Cantwell have introduced bipartisan legislation to reinstate the Glass-Steagall Act, the Depression-era reform that separated commercial banking from investment banking. Mr McCain and Ms Cantwell thus join a very distinguished group of reformers, led by the estimable Paul Volcker and other notables including Nicholas Brady, the former Treasury secretary.

This group traces the origins of the current crisis to Glass-Steagall's 1999 repeal, and would once again separate the “safe and predictable” activity of taking deposits and making loans from “risky” underwriting, trading and hedging. The new financial sobriety reflected in this proposal sees risk as the cause of the current crisis, if not the nastiest four-letter word in the English language.

But reimposing Glass-Steagall would lock our financial system in the amber of the past. The notion of recycling a solution from three generations ago, created long before globalisation, computers and the internet, and widely regarded as grossly outdated 15 years ago, even by today's proponents of reimposition, would be laughable were it not advanced by so many otherwise serious people. But it would be a seriously flawed policy.